Guidelines for Environmental Infection Control in

Centers for Disease Control and Prevention

Healthcare Infection Control Practices Advisory

Committee (HICPAC)

Guidelines for Environmental Infection Control in

Health-Care Facilities

Abstract

Background:

Although the environment serves as a reservoir for a variety of microorganisms, it is rarely implicated in

disease transmission except in the immunocompromised population. Inadvertent exposures to

environmental opportunistic pathogens (e.g.,

Aspergillus

spp. and

Legionella

spp.) or airborne

pathogens (e.g.,

Mycobacterium tuberculosis

and varicella-zoster virus) may result in infections with

significant morbidity and/or mortality. Lack of adherence to established standards and guidance (e.g.,

water quality in dialysis, proper ventilation for specialized care areas such as operating rooms, and

proper use of disinfectants) can result in adverse patient outcomes in health-care facilities.

Objective:

The objective is to develop an environmental infection-control guideline that reviews and reaffirms

strategies for the prevention of environmentally-mediated infections, particularly among health-care

workers and immunocompromised patients. The recommendations are evidence-based whenever

possible.

Search Strategies:

The contributors to this guideline reviewed predominantly English-language articles identified from

MEDLINE literature searches, bibliographies from published articles, and infection-control textbooks.

Criteria for Selecting Citations and Studies for This Review:

Articles dealing with outbreaks of infection due to environmental opportunistic microorganisms and

epidemiological- or laboratory experimental studies were reviewed. Current editions of guidelines and

standards from organizations (i.e., American Institute of Architects [AIA], Association for the

Advancement of Medical Instrumentation [AAMI], and American Society of Heating, Refrigeration,

and Air-Conditioning Engineers [ASHRAE]) were consulted. Relevant regulations from federal

agencies (i.e., U.S. Food and Drug Administration [FDA]; U.S. Department of Labor, Occupational

Safety and Health Administration [OSHA]; U.S. Environmental Protection Agency [EPA]; and U.S.

Department of Justice) were reviewed. Some topics did not have well-designed, prospective studies nor

reports of outbreak investigations. Expert opinions and experience were consulted in these instances.

Types of Studies:

Reports of outbreak investigations, epidemiological assessment of outbreak investigations with control

strategies, and

in vitro

environmental studies were assessed. Many of the recommendations are derived

from empiric engineering concepts and reflect industry standards. A few of the infection-control

measures proposed cannot be rigorously studied for ethical or logistical reasons.

Outcome Measures:

Infections caused by the microorganisms described in this guideline are rare events, and the effect of

these recommendations on infection rates in a facility may not be readily measurable. Therefore, the

following steps to measure performance are suggested to evaluate these recommendations:

Document whether infection-control personnel are actively involved in all phases of a health-

care facility’s demolition, construction, and renovation. Activities should include performing a

risk assessment of the necessary types of construction barriers, and daily monitoring and

documenting of the presence of negative airflow within the construction zone or renovation

area.

Monitor and document daily the negative airflow in airborne infection isolation rooms (AII) and

positive airflow in protective environment rooms (PE), especially when patients are in these

rooms.

Perform assays at least once a month by using standard quantitative methods for endotoxin in

water used to reprocess hemodialyzers, and for heterotrophic, mesophilic bacteria in water used

to prepare dialysate and for hemodialyzer reprocessing.

Evaluate possible environmental sources (e.g., water, laboratory solutions, or reagents) of

specimen contamination when nontuberculous mycobacteria (NTM) of unlikely clinical

importance are isolated from clinical cultures. If environmental contamination is found,

eliminate the probable mechanisms.

Document policies to identify and respond to water damage. Such policies should result in

either repair and drying of wet structural materials within 72 hours, or removal of the wet

material if drying is unlikely within 72 hours.

Main Results:

Infection-control strategies and engineering controls, when consistently implemented, are effective in

preventing opportunistic, environmentally-related infections in immunocompromised populations.

Adherence to proper use of disinfectants, proper maintenance of medical equipment that uses water

(e.g., automated endoscope reprocessors and hydrotherapy equipment), water-quality standards for

hemodialysis, and proper ventilation standards for specialized care environments (i.e., airborne infection

isolation [AII], protective environment [PE], and operating rooms [ORs]), and prompt management of

water intrusion into facility structural elements will minimize health-care–associated infection risks and

reduce the frequency of pseudo-outbreaks. Routine environmental sampling is not advised except in the

few situations where sampling is directed by epidemiologic principles and results can be

applied

directly to infection control decisions, and for water quality determinations in hemodialysis.

Reviewers’ Conclusions:

Continued compliance with existing environmental infection control measures will decrease the risk of

health-care–associated infections among patients, especially the immunocompromised, and health-care

workers.

vii

List of Abbreviations Used in This Publication

AAA

animal-assisted

activity

AAMI

Association for the Advancement of Medical Instrumentation

AAT

animal-assisted

therapy

ACGIH

American Council of Governmental Industrial Hygienists

ACH

air changes per hour

ADA

Americans with Disabilities Act

AER

automated endoscope reprocessor

AFB

acid-fast

bacilli

AHA

American Hospital Association

AHJ

authorities having jurisdiction

AIA

American Institute of Architects

AII

airborne infection isolation

AmB

amphotericin

ANC

absolute neutrophil count

ANSI

American National Standards Institute

AORN

Association of periOperative Registered Nurses

ASHE

American Society for Healthcare Engineering

ASHRAE

American Society of Heating, Refirgeration, and Air-Conditioning Engineers

BCG

Bacille

Calmette-Guérin

BCYE

buffered charcoal yeast extract medium

BHI

brain-heart

infusion

BMBL

CDC/NIH publication “Biosafety in Microbiological and Biomedical Laboratories”

BOD

biological oxygen demand

BSE

bovine spongiform encephalopathy

BSL

biosafety

level

Centigrade

CAPD

continuous ambulatory peritoneal dialysis

CCPD

continual cycling peritoneal dialysis

CMAD

count median aerodynamic diameter

CDC

U.S. Centers for Disease Control and Prevention

CFR

Code of Federal Regulations

CFU

colony-forming

unit

CJD

Creutzfeldt-Jakob

disease

centimeter

CMS

U.S. Centers for Medicare and Medicaid Services

CPL

compliance document (OSHA)

CT/EC

cooling tower/evaporative condenser

DFA

direct fluorescence assay; direct fluorescent antibody

DHHS

U.S. Department of Health and Human Services

DHBV

duck hepatitis B virus

DNA

deoxyribonucleic

acid

DOP

dioctylphthalate

DOT

U.S. Department of Transportation

environment of care (JCAHO)

ELISA

enzyme-linked immunosorbent assay

EPA

U.S. Environmental Protection Agency

ESRD

end-stage renal disease

viii

endotoxin

unit

Fahrenheit

FDA

U.S. Food and Drug Administration

FIFRA

Federal Insecticide, Fungicide, and Rodenticide Act

FRC

free

residual

chlorine

foot

(feet)

FTC

U.S. Federal Trade Commission

GISA

glycopeptide

intermediate

resistant

Staphylococcus aureus

HBV

hepatitis B virus

HCV

hepatitis C virus

HEPA

high efficiency particulate air

HICPAC

Healthcare Infection Control Practices Advisory Committee

HIV

human

immunodeficiency

virus

HPV

human papilloma virus

HSCT

hematopoietic stem cell transplant

HVAC

heating, ventilation, air conditioning

ICRA

infection control risk assessment

ICU

intensive care unit

50% median infectious dose

IPD

intermittent peritoneal dialysis

JCAHO

Joint Commission on Accreditation of Healthcare Organizations

kilogram

liter

MAC

Mycobacterium avium

complex; also used to denote MacConkey agar

MDRO

multiple-drug resistant organism

MIC

minimum inhibitory concentration

µm

micrometer;

micron

milliliter

min

minute

milligram

MMAD

mass median aerodynamic diameter

MMWR

“Morbidity and Mortality Weekly Report”

MRSA

methicillin-resistant

Staphylococcus aureus

MSDS

material safety data sheet

Normal

NaCl

sodium

chloride

NaOH

sodium

hydroxide

NCID

National Center for Infectious Diseases

NCCDPHP

National Center for Chronic Disease Prevention and Health Promotion

NCCLS

National Committee for Clinical Laboratory Standards

nanogram

NICU

neonatal intensive care unit

NIH

U.S. National Institutes of Health

NIOSH

National Institute for Occupational Safety and Health

nanometer

NNIS

National Nosocomial Infection Surveillance

NTM

nontuberculous

mycobacteria

OPL

on-premises

laundry

OSHA

U.S. Occupational Safety and Health Administration

Pascal

PCP

Pneumocystis carinii

pneumonia

PCR

polymerase chain reaction

peritoneal

dialysis

protective

environment

PEL

permissible exposure limit

PPE

personal protective equipment

ppm

parts

per

million

PVC

polyvinylchloride

RAPD

randomly amplified polymorphic DNA

RODAC

replicate organism direct agar contact

RSV

respiratory

syncytial

virus

reverse

osmosis

SARS

severe acute respiratory syndrome

SARS-CoV

SARS

coronavirus

sec

second

spp

species

SSI

surgical site infection

tuberculosis

TLV®-TWA

threshold limit value-time weighted average

TSA

tryptic soy agar

TSB

tryptic soy broth

TSE

transmissible spongiform encephalopathy

U.S.

United

States

USC

United States Code

USDA

U.S. Department of Agriculture

USPS

U.S. Postal Service

ultraviolet

UVGI

ultraviolet germicidal irradiation

VAV

variable air ventilation

vCJD

variant Creutzfeldt-Jakob disease

VISA

vancomycin intermediate resistant

Staphylococcus aureus

VRE

vancomycin-resistant

Enterococcus

VRSA

vancomycin-resistant

Staphylococcus aureus

v/v

volume/volume

VZV

varicella-zoster

virus

Note: Use of trade names and commercial sources is for identification only and does not imply
endorsement by the U.S. Department of Health and Human Services. References to non-CDC
sites on the Internet are provided as a service to the reader and does not constitute or imply
endorsement of these organization s or their programs by CDC or the U.S. Department of Health
and Human Services. CDC is not responsible for the content of pages found at these sites.

HICPAC Members, February 2002

Robert A. Weinstein, MD

Jane D. Siegel, MD

Chair Co-Chair

Cook County Hospital

University of Texas Southwestern Medical Center

Chicago, IL

Dallas, TX

Michele L. Pearson, MD

Raymond Y.W. Chinn, MD

Executive Secretary

Sharp Memorial Hospital

Centers for Disease Control and Prevention

San Diego, CA

Atlanta, GA

Alfred DeMaria, Jr., MD

Elaine L. Larson, RN, PhD

Massachusetts Department of Public Health

Columbia University School of Nursing

Jamaica Plain, MA

New York, NY

James T. Lee, MD, PhD

Ramon E. Moncada, MD

University of Minnesota

Coronado Physician’s Medical Center

VA Medical Center

Coronado, CA

St. Paul, MN

William A. Rutala, PhD, MPH, CIC

William E. Scheckler, MD

University of North Carolina School of

University of Wisconsin Medical School

Medicine

Madison, WI

Chapel Hill, NC

Beth H. Stover, RN, CIC

Marjorie A. Underwood, RN, BSN, CIC

Kosair Children’s Hospital

Mt. Diablo Medical Center

Louisville, KY

Concord, CA

Liaison Members

Loretta L. Fauerbach, MS, CIC

Sandra L. Fitzler, RN

Association for Professionals in Infection

American Health Care Association

Control and Epidemiology (APIC)

Washington, DC

Dorothy M. Fogg, RN, BSN, MA

Stephen F. Jencks, MD, MPH

Association of periOperative Registered

U.S. Centers for Medicare and Medicaid

Nurses (AORN)

Services

Denver, CO

Baltimore, MD

Chiu S. Lin, PhD

James P. Steinberg, MD

U.S. Food and Drug Administration

Society for Healthcare Epidemiology of America,

Rockville, MD

Inc. (SHEA)

Atlanta,

xii

Liaison Members (continued)

Michael L. Tapper, MD

Advisory Committee for the Elimination of

Tuberculosis (ACET)

New York, NY

Expert Reviewers

Trisha Barrett, RN, MBA, CIC

Judene Bartley, MS, MPH, CIC

Alta Bates Medical Center

Epidemiology Consulting Services, Inc.

Berkeley, CA

Beverly Hills, MI

Michael Berry

Col. Nancy Bjerke, BSN, MA, MEd, MPH, CIC

University of North Carolina

(USAF, Retired)

Chapel Hill, NC

Infection Control Associates (ICA)

San

Antonio,

Walter W. Bond, MS

Cheryl Carter, RN

RCSA, Inc.

University of Iowa Health Center

Lawrenceville, GA

Iowa City, IA

Douglas Erickson, FASHE

Martin S. Favero, PhD

American Society for Healthcare

Advanced Sterilization Products, Johnson and

Engineering (ASHE)

Johnson

Park Ridge, IL

Irvine, CA

Richard Miller, MD

Col. Shannon E. Mills, DDS

University of Louisville School of Medicine

HQ USAF / Surgeon General Detail

Louisville, KY

Bolin AFB, DC

Gina Pugliese, RN, MS

Craig E. Rubens, MD, PhD

Premier Safety Institute

Children’s Hospital and Medical Center

Oak Brook, IL

Seattle, WA

James D. Scott, PE

Andrew J. Streifel, MPH, REHS

Michigan Department of Consumer and

University of Minnesota

Industry Services

Minneapolis, MN

Lansing, MI

Dale Woodin

American Society for Healthcare Engineering

(ASHE)

Chicago, IL

Executive Summary

The

Guidelines for Environmental Infection Control in Health-Care Facilities

is a compilation of

recommendations for the prevention and control of infectious diseases that are associated with health-

care environments. This document a) revises multiple sections from previous editions of the Centers for

Disease Control and Prevention [CDC] document titled

Guideline for Handwashing and Hospital

Environmental Control

;

1, 2

b) incorporates discussions of air and water environmental concerns from

CDC’s

Guideline for the Prevention of Nosocomial Pneumonia

;

c) consolidates relevant environmental

infection-control measures from other CDC guidelines;

4–9

and d) includes two topics not addressed in

previous CDC guidelines — infection-control concerns related to animals in health-care facilities and

water quality in hemodialysis settings.

Part I of this report,

Background Information: Environmental Infection Control in Health-Care

Facilities

, provides a comprehensive review of the scientific literature. Attention is given to

engineering and infection-control concerns during construction, demolition, renovation, and repairs of

health-care facilities. Use of an infection-control risk assessment is strongly supported before the start of

these or any other activities expected to generate dust or water aerosols. Also reviewed in Part I are

infection-control measures used to recover from catastrophic events (e.g., flooding, sewage spills, loss

of electricity and ventilation, and disruption of the water supply) and the limited effects of

environmental surfaces, laundry, plants, animals, medical wastes, cloth furnishings, and carpeting on

disease transmission in healthcare facilities.

Part II of this guideline,

Recommendations for Environmental Infection Control in Health-Care

Facilities

, outlines environmental infection control in health-care facilities, describing measures for

preventing infections associated with air, water, and other elements of the environment. These

recommendations represent the views of different divisions within CDC’s National Center for Infectious

Diseases (NCID) (e.g., the Division of Healthcare Quality Promotion [DHQP] and the Division of

Bacterial and Mycotic Diseases [DBMD]) and the consensus of the Healthcare Infection Control

Practices Advisory Committee (HICPAC), a 12-member group that advises CDC on concerns related to

the surveillance, prevention, and control of health-care–associated infections, primarily in U.S. health-

care facilities.

In 1999, HICPAC’s infection-control focus was expanded from acute-care hospitals to

all venues where health care is provided (e.g., outpatient surgical centers, urgent care centers, clinics,

outpatient dialysis centers, physicians’ offices, and skilled nursing facilities). The topics addressed in

this guideline are applicable to the majority of health-care venues in the United States. This document

is intended for use primarily by infection-control professionals (ICPs), epidemiologists, employee health

and safety personnel, information system specialists, administrators, engineers, facility managers,

environmental service professionals, and architects for health-care facilities.

Key recommendations include a) infection-control impact of ventilation system and water system

performance; b) establishment of a multidisciplinary team to conduct infection-control risk assessment;

c) use of dust-control procedures and barriers during construction, repair, renovation, or demolition; d)

environmental infection-control measures for special care areas with patients at high risk; e) use of

airborne particle sampling to monitor the effectiveness of air filtration and dust-control measures; f)

procedures to prevent airborne contamination in operating rooms when infectious tuberculosis [TB]

patients require surgery; g) guidance regarding appropriate indications for routine culturing of water as

part of a comprehensive control program for legionellae; h) guidance for recovering from water system

disruptions, water leaks, and natural disasters [e.g., flooding]; i) infection-control concepts for

equipment that uses water from main lines [e.g., water systems for hemodialysis, ice machines,

hydrotherapy equipment, dental unit water lines, and

automated endoscope reprocessors]); j)

environmental surface cleaning and disinfection

strategies with

respect to antibiotic-resistant

microorganisms; k) infection-control procedures for health-care laundry; l) use of animals in health care

for activities and therapy; m) managing the presence of service animals in health-care facilities; n)

infection-control strategies for when animals receive treatment in human health-care facilities; and o) a

call to reinstate the practice of inactivating amplified cultures and stocks of microorganisms on-site

during medical waste treatment.

Whenever possible, the recommendations in Part II are based on data from well-designed scientific

studies. However, certain of these studies were conducted by using narrowly defined patient

populations or for specific health-care settings (e.g., hospitals versus long-term care facilities), making

generalization of findings potentially problematic. Construction standards for hospitals or other health-

care facilities may not apply to residential home-care units. Similarly, infection-control measures

indicated for immunosuppressed patient care are usually not necessary in those facilities where such

patients are not present. Other recommendations were derived from knowledge gained during infectious

disease investigations in health-care facilities, where successful termination of the outbreak was often

the result of multiple interventions, the majority of which cannot be independently and rigorously

evaluated. This is especially true for construction situations involving air or water.

Other recommendations are derived from empiric engineering concepts and may reflect an industry

standard rather than an evidence-based conclusion. Where recommendations refer to guidance from the

American Institute of Architects (AIA), the statements reflect standards intended for new construction

or renovation. Existing structures and engineered systems are expected to be in continued compliance

with the standards in effect at the time of construction or renovation. Also, in the absence of scientific

confirmation, certain infection-control recommendations that cannot be rigorously evaluated are based

on a strong theoretical rationale and suggestive evidence. Finally, certain recommendations are derived

from existing federal regulations. The references and the appendices comprise Parts III and IV of this

document, respectively.

Infections caused by the microorganisms described in these guidelines are rare events, and the effect of

these recommendations on infection rates in a facility may not be readily measurable. Therefore, the

following steps to measure performance are suggested to evaluate these recommendations (Box 1):

Box 1. Environmental infection control: performance measures

Document whether infection-control personnel are actively involved in all phases of a health-care
facility’s demolition, construction, and renovation. Activities should include performing a risk
assessment of the necessary types of construction barriers, and daily monitoring and documenting
of the presence of negative airflow within the construction zone or renovation area.

Monitor and document daily the negative airflow in airborne infection isolation (AII) rooms and
positive airflow in protective environment (PE) rooms, especially when patients are in these rooms.

Perform assays at least once a month by using standard quantitative methods for endotoxin in
water used to reprocess hemodialyzers, and for heterotrophic and mesophilic bacteria in water
used to prepare dialysate and for hemodialyzer reprocessing.

Evaluate possible environmental sources (e.g., water, laboratory solutions, or reagents) of specimen
contamination when nontuberculous mycobacteria (NTM) of unlikely clinical importance are
isolated from clinical cultures. If environmental contamination is found, eliminate the probable
mechanisms.

Document policies to identify and respond to water damage. Such policies should result in either
repair and drying of wet structural or porous materials within 72 hours, or removal of the wet
material if drying is unlikely with 72 hours.

Topics outside the scope of this document include a) noninfectious adverse events (e.g., sick building

syndrome); b) environmental concerns in the home; c) home health care; d) bioterrorism; and e) health-

care–associated foodborne illness. This document includes only limited discussion of a)

handwashing/hand hygiene; b) standard precautions; and c) infection-control measures used to prevent

instrument or equipment contamination during patient care (e.g., preventing waterborne contamination

of nebulizers or ventilator humidifiers). These topics are mentioned only if they are important in

minimizing the transfer of pathogens to and from persons or equipment and the environment. Although

the document discusses principles of cleaning and disinfection as they are applied to maintenance of

environmental surfaces, the full discussion of sterilization and disinfection of medical instruments and

direct patient-care devices is deferred for inclusion in the

Guideline for Disinfection and Sterilization in

Health-Care Facilities

, a document currently under development. Similarly, the full discussion of hand

hygiene is available as the

Guideline for Hand Hygiene in Health-Care Settings: Recommendations of

the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA
Hand Hygiene Task Force

. Where applicable, the

Guidelines for Environmental Infection Control in

Health-Care Facilities

are consistent in content to the drafts available as of October 2002 of both the

revised

Guideline for Prevention of Health-Care–Associated Pneumonia

and

Guidelines for Preventing

the Transmission of Mycobacterium tuberculosis in Health-Care Facilities

This guideline was prepared by CDC staff members from NCID and the National Center for Chronic

Disease Prevention and Health Promotion (NCCDPHP) and the designated HICPAC advisor.

Contributors to this document reviewed predominantly English-language manuscripts identified from

reference searches using the National Library of Medicine’s MEDLINE, bibliographies of published

articles, and infection-control textbooks. Working drafts of the guideline were reviewed by CDC

scientists, HICPAC committee members, and experts in infection control, engineering, internal

medicine, infectious diseases, epidemiology, and microbiology. All recommendations in this guideline

may not reflect the opinions of all reviewers.

Part I. Background Information: Environmental
Infection Control in Health-Care Facilities

A. Introduction

The health-care environment contains a diverse population of microorganisms, but only a few are

significant pathogens for susceptible humans. Microorganisms are present in great numbers in moist,

organic environments, but some also can persist under dry conditions. Although pathogenic

microorganisms can be detected in air and water and on fomites, assessing their role in causing infection

and disease is difficult.

Only a few reports clearly delineate a “cause and effect” with respect to the

environment and in particular, housekeeping surfaces.

Eight criteria are used to evaluate the strength of evidence for an environmental source or means of

transmission of infectious agents (Box 2).

11, 12

Applying these criteria to disease investigations allows

scientists to assess the contribution of the environment to disease transmission. An example of this

application is the identification of a pathogen (e.g., vancomycin-resistant enterococci [VRE]) on an

environmental surface during an outbreak. The presence of the pathogen does not establish its causal

role; its transmission from source to host could be through indirect means (e.g., via hand transferral).

The surface, therefore, would be considered one of a number of potential reservoirs for the pathogen,

but not the “de

facto” source of exposure. An understanding of how infection occurs after

exposure,

based on the principles of the “chain of infection,” is also important in evaluating the contribution of the

environment to health-care–associated disease.

All of the components of the “chain” must be

operational for infection to occur (Box 3).

Box 2. Eight criteria for evaluating the strength of evidence for environmental sources of
infection* +

The organism can survive after inoculation onto the fomite.

The organism can be cultured from in-use fomites.

The organism can proliferate in or on the fomite.

Some measure of acquisition of infection cannot be explained by other recognized modes of
transmission.

Retrospective case-control studies show an association between exposure to the fomite and
infection.

Prospective case-control studies may be possible when more than one similar type of fomite is in
use.

Prospective studies allocating exposure to the fomite to a subset of patients show an assication
between exposure and infection.

Decontamination of the fomite results in the elimination of infection transmission.

* These criteria are listed in order of strength of evidence.

+ Adapted from references 11 and 12.

Box 3. Chain of infection components*

Adequate number of pathogenic organisms (dose)

Pathogenic organisms of sufficient virulence

A susceptible host

An appropriate mode of transmission or transferal of the organism in sufficient number from
source to host

The correct portal of entry into the host

* Adapted from reference 13.

The presence of the susceptible host is one of these components that underscores the importance of the

health-care environment and opportunistic pathogens on fomites and in air and water. As a result of

advances in medical technology and therapies (e.g., cytotoxic chemotherapy and transplantation

medicine), more patients are becoming immunocompromised in the course of treatment and are

therefore at increased risk for acquiring health-care–associated opportunistic infections. Trends in

health-care delivery (e.g., early discharge of patients from acute care facilities) also are changing the

distribution of patient populations and increasing the number of immunocompromised persons in non-

acute-care hospitals. According to the American Hospital Association (AHA), in 1998, the number of

hospitals in the United States totaled 6,021; these hospitals had a total of 1,013,000 beds,

representing

a 5.5% decrease in the number of acute-care facilities and a 10.2% decrease in the number of beds over

the 5-year period 1994–1998.

In addition, the total average daily number of patients receiving care in

U.S. acute-care hospitals in 1998 was 662,000 (65.4%) – 36.5% less than the 1978 average of

1,042,000.

As the number of acute-care hospitals declines, the length of stay in these facilities is

concurrently decreasing, particularly for immunocompetent patients. Those patients remaining in acute-

care facilities are likely to be those requiring extensive medical interventions who therefore at high risk

for opportunistic infection

The growing population of severely immunocompromised patients is at odds with demands on the

health-care industry to remain viable in the marketplace; to incorporate modern equipment, new

diagnostic procedures, and new treatments; and to construct new facilities. Increasing numbers of

health-care facilities are likely to be faced with construction in the near future as hospitals consolidate to

reduce costs, defer care to ambulatory centers and satellite clinics, and try to create more “home-like”

acute-care settings. In 1998, approximately 75% of health-care–associated construction projects

focused on renovation of existing outpatient facilities or the building of such facilities;

the number of

projects associated with outpatient health care rose by 17% from 1998 through 1999.

An aging

population is also creating increasing demand for assisted-living facilities and skilled nursing centers.

Construction of assisted-living facilities in 1998 increased 49% from the previous year, with 138

projects completed at a cost of $703 million.

Overall, from 1998 to 1999, health-care–associated

construction costs increased by 28.5%, from $11.56 billion to $14.86 billion.

Environmental disturbances associated with construction activities near health-care facilities pose

airborne and waterborne disease threats risks for the substantial number of patients who are at risk for

health-care–associated opportunistic infections. The increasing age of hospitals and other health-care

facilities is also generating ongoing need for repair and remediation work (e.g., installing wiring for new

information systems, removing old sinks, and repairing elevator shafts) that can introduce or increase

contamination of the air and water in patient-care environments. Aging equipment, deferred

maintenance, and natural disasters provide additional mechanisms for the entry of environmental

pathogens into high-risk patient-care areas.

Architects, engineers, construction contractors, environmental health scientists, and industrial hygienists

historically have directed the design and function of hospitals’ physical plants. Increasingly, however,

because of the growth in the number of susceptible patients and the increase in construction projects, the

involvement of hospital epidemiologists and infection-control professionals is required. These experts

help make plans for building, maintaining, and renovating health-care facilities to ensure that the

adverse impact of the environment on the incidence of health-care–associated infections is minimal.

The following are examples of adverse outcomes that could have been prevented had such experts been

involved in the planning process: a) transmission of infections caused by

Mycobacterium tuberculosis

varicella-zoster virus (VZV), and measles (i.e., rubeola) facilitated by inappropriate air-handling

systems in health-care facilities;

b) disease outbreaks caused by

Aspergillus

spp.,

17–19

Mucoraceae

and

Penicillium

spp. associated with the absence of environmental controls during periods of health-care

facility-associated construction;

c) infections and/or colonizations of patients and staff with

vancomycin-resistant

Enterococcus faecium

[VRE] and

Clostridium difficile

acquired indirectly from

contact with organisms present on environmental surfaces in health-care facilities;

22–25

and d) outbreaks

and pseudoepidemics of legionellae,

26, 27

Pseudomonas aeruginosa

28–30

and the nontuberculous

mycobacteria (NTM)

31, 32

linked to water and aqueous solutions used in health-care facilities. The

purpose of this guideline is to provide useful information for both health-care professionals and

engineers in efforts to provide a safe environment in which quality health care may be provided to

patients. The recommendations herein provide guidance to minimize the risk for and prevent

transmission of pathogens in the indoor environment.

B. Key Terms Used in this Guideline

Although Appendix A provides definitions for terms discussed in Part I, several terms that pertain to

specific patient-care areas and patients who are at risk for health-care–associated opportunistic

infections are presented here. Specific engineering parameters for these care areas are discussed more

fully in the text.

Airborne Infection Isolation (AII)

refers to the isolation of patients infected with

organisms spread via airborne droplet nuclei <5 µm in diameter. This isolation area receives numerous

air changes per hour (ACH) (>12 ACH for new construction as of 2001; >6 ACH for construction

before 2001), and is under negative pressure, such that the direction of the airflow is from the outside

adjacent space (e.g., corridor) into the room. The air in an AII room is preferably exhausted to the

outside, but may be recirculated provided that the return air is filtered through a high efficiency

particulate air (HEPA) filter. The use of personal respiratory protection is also indicated for persons

entering these rooms.

Protective Environment (PE)

is a specialized patient-care area, usually in a hospital, with a positive

airflow relative to the corridor (i.e., air flows from the room to the outside adjacent space). The

combination of HEPA filtration, high numbers of air changes per hour (>12 ACH), and minimal leakage

of air into the room creates an environment that can safely accommodate patients who have undergone

allogeneic hematopoietic stem cell transplant (HSCT).

Immunocompromised patients

are those patients whose immune mechanisms are deficient because of

immunologic disorders (e.g., human immunodeficiency virus [HIV] infection, congenital immune

deficiency syndrome, chronic diseases [such as diabetes, cancer, emphysema, and cardiac failure]) or

immunosuppressive therapy (e.g., radiation, cytotoxic chemotherapy, anti-rejection medication, and

steroids). Immunocompromised patients who are identified as

high-risk patients

have the greatest risk

of infection caused by airborne or waterborne microorganisms. Patients in this subset include those who

are severely neutropenic for prolonged periods of time (i.e., an absolute neutrophil count [ANC] of <500

cells/mL), allogeneic HSCT patients, and those who have received intensive chemotherapy (e.g.,

childhood acute myelogenous leukemia patients).

C. Air

1. Modes of Transmission of Airborne Diseases

A variety of airborne infections in susceptible hosts can result from exposures to clinically significant

microorganisms released into the air when environmental reservoirs (i.e., soil, water, dust, and decaying

organic matter) are disturbed. Once these materials are brought indoors into a health-care facility by

any of a number of vehicles (e.g., people, air currents, water, construction materials, and equipment),

the attendant microorganisms can proliferate in various indoor ecological niches and, if subsequently

disbursed into the air, serve as a source for airborne health-care–associated infections.

Respiratory infections can be acquired from exposure to pathogens contained either in droplets or

droplet nuclei. Exposure to microorganisms in droplets (e.g., through aerosolized oral and nasal

secretions from infected patients

) constitutes a form of direct contact transmission. When droplets are

produced during a sneeze or cough, a cloud of infectious particles >5 µm in size is expelled, resulting in

the potential exposure of susceptible persons within 3 feet of the source person.

Examples of

pathogens spread in this manner are influenza virus, rhinoviruses, adenoviruses, and respiratory

syncytial virus (RSV). Because these agents primarily are transmitted directly and because the droplets

tend to fall out of the air quickly, measures to control air flow in a health-care facility (e.g., use of

negative pressure rooms) generally are not indicated for preventing the spread of diseases caused by

these agents. Strategies to control the spread of these diseases are outlined in another guideline.

The spread of airborne infectious diseases via droplet nuclei is a form of indirect transmission.

Droplet nuclei are the residuals of droplets that, when suspended in air, subsequently dry and produce

particles ranging in size from 1–5 µm. These particles can a) contain potentially viable microorganisms,

b) be protected by a coat of dry secretions, c) remain suspended indefinitely in air, and d) be transported

over long distances. The microorganisms in droplet nuclei persist in favorable conditions (e.g., a dry,

cool atmosphere with little or no direct exposure to sunlight or other sources of radiation). Pathogenic

microorganisms that can be spread via droplet nuclei include

Mycobacterium tuberculosis

, VZV,

measles virus (i.e., rubeola), and smallpox virus (i.e., variola major).

Several environmental pathogens

have life-cycle forms that are similar in size to droplet nuclei and may exhibit similar behavior in the

air. The spores of

Aspergillus fumigatus

have a diameter of 2–3.5 µm, with a settling velocity estimated

at 0.03 cm/second (or about 1 meter/hour) in still air. With this enhanced buoyancy, the spores, which

resist desiccation, can remain airborne indefinitely in air currents and travel far from their source.

2. Airborne Infectious Diseases in Health-Care Facilities

a. Aspergillosis and Other Fungal Diseases

Aspergillosis is caused by molds belonging to the genus

Aspergillus

spp. are prototype

health-care–acquired pathogens associated with dusty or moist environmental conditions. Clinical and

epidemiologic aspects of aspergillosis (Table 1) are discussed extensively in another guideline.

Table 1. Clinical and epidemiologic characteristics of aspergillosis

References

Causative agents

Aspergillus fumigatus

(90%–95% of

Aspergillus

infections among

hematopoietic stem cell transplant (HSCT) patients;

A. flavus, A. niger, A.

terreus, A. nidulans

36–43

Modes of transmission

Airborne transmission of fungal spores; direct inhalation; direct inoculation

from environmental sources (rare)

Activities associated with

infection

Construction, renovation, remodeling, repairs, building demolition; rare

episodes associated with fomites

44–51

Clinical syndromes and

diseases

Acute invasive: pneumonia

; ulcerative tracheobronchitis; osteomyelitis;

abscesses (aspergillomas) of the lungs, brain, liver, spleen, and kidneys;

thrombosis of deep blood vessels; necrotizing skin ulcers; endophthalmitis;

and sinusitis

Chronic invasive

: chronic pneumonitis

Hypersensity

: allergic bronchopulmonary aspergillosis

Cutaneous

: primary skin and burn-wound infections

44, 45, 52–58

Patient populations at

greatest risk

Hematopoietic stem cell transplant patients (HSCT):

immunocompromised patients (i.e., those with underlying disease), patients

undergoing chemotherapy, organ transplant recipients, preterm neonates,

hemodialysis patients, patients with identifiable immune system deficiencies

who receive care in general intensive care units (ICUs), and cystic fibrosis

patients (may be colonized, occasionally become infected)

36, 59–78

Factors affecting severity

and outcomes

The immune status of the patient and the duration of severe neutropenia

79, 80

Occurrence

Rare and sporadic, but increasing as proportion of immunocompromised

patients increases; 5% of HSCT patients infected, <5% of solid organ

transplant recipients infected

36, 37, 81–88

Mortality rate

Rate can be as high as 100% if severe neutropenia persists; 13%–80%

mortality among leukemia patients

58, 83, 89, 90

Aspergillus

spp. are ubiquitous, aerobic fungi that occur in soil, water, and decaying vegetation; the

organism also survives well in air, dust, and moisture present in health-care facilities.

91–93

The presence

of aspergilli in the health-care facility environment is a substantial extrinsic risk factor for opportunistic

invasive aspergillosis (invasive aspergillosis being the most serious form of the disease).

69, 94

Site

renovation and construction can disturb

Aspergillus

-contaminated dust and produce bursts of airborne

fungal spores. Increased levels of atmospheric dust and fungal spores have been associated with

clusters of health-care–acquired infections in immunocompromised patients.

17, 20, 44, 47, 49, 50, 95–98

Absorbent building materials (e.g., wallboard) serve as an ideal substrate for the proliferation of this

organism if they become and remain wet, thereby increasing the numbers of fungal spores in the area.

Patient-care items, devices, and equipment can become contaminated with

Aspergillus

spp. spores and

serve as sources of infection if stored in such areas.

Most cases of aspergillosis are caused by

Aspergillus fumigatus

, a thermotolerant/thermophilic fungus

capable of growing over a temperature range from 53.6°F–127.4°F (12°C–53°C); optimal growth occurs

at approximately 104°F (40°C), a temperature inhibitory to most other saprophytic fungi.

It can use

cellulose or sugars as carbon sources; because its respiratory process requires an ample supply of

carbon, decomposing organic matter is an ideal substrate.

Other opportunistic fungi that have been occasionally linked with health-care–associated infections are

members of the order

Mucorales

(e.g.,

Rhizopus

spp.) and miscellaneous moniliaceous molds (e.g.,

Fusarium

spp. and

Penicillium

spp.) (Table 2). Many of these fungi can proliferate in moist

environments (e.g., water-damaged wood and building materials). Some fungi (e.g.,

Fusarium

spp. and

Pseudoallescheria

spp.) also can be airborne pathogens.

100

As with aspergillosis, a major risk factor for

disease caused by any of these pathogens is the host’s severe immunosuppression from either

underlying disease or immunosuppressive therapy.

101, 102

Table 2. Environmental fungal pathogens: entry into and contamination of the health-
care facility

Implicated environmental vehicle

References

Aspergillus spp.

Improperly functioning ventilation systems

20, 46, 47, 97, 98, 103, 104

Air

filters

*,+

17, 18, 105–107

Air filter frames

17, 18

Window

air

conditioners

Backflow of contaminated air

107

Air exhaust contamination

104

False ceilings

48, 57, 97, 108

Fibrous insulation and perforated metal ceilings

Acoustic ceiling tiles, plasterboard

18, 109

Fireproofing material

48, 49

Damp wood building materials

Opening doors to construction site

110

Construction

Open windows

20, 108, 111

Disposal conduit door

Hospital vacuum cleaner

Elevator

112

Arm

boards

Walls

113

Unit

kitchen

114

Food 21

Ornamental

plants

Mucorales / Rhizopus spp.

Air filter

20, 115

False

ceilings

Heliport

115

Scedosporium spp.

Construction

116

(Table 2. continued)

Implicated environmental vehicles

References

Penicillium spp.

Rotting cabinet wood, pipe leak

Ventilation

duct

fiberglass insulation

112

Air

filters

105

Topical

anesthetic

117

Acremonium spp.

Air

filters

105

Cladosporium spp.

Air

filters

105

Sporothrix

Construction

(pseudoepidemic)

118

*. Pigeons, their droppings and roosts are associated with spread of

Aspergillus, Cryptococcus,

and

Histoplasma

spp. There have been at

least three outbreaks linked to contamination of the filtering systems from bird droppings

98, 103, 104

Pigeon mites may gain access into a

health-care facility through the ventilation system.

119

+. The American Institute of Architects (AIA) standards stipulate that for new or renovated construction a) exhaust outlets are to be placed

>25 feet from air intake systems, b) the bottom of outdoor air intakes for HVAC systems should be 6 feet above ground or 3 feet above

roof level, and c) exhaust outlets from contaminated areas are situated above the roof level and arranged to minimize the recirculation of

exhausted air back into the building.

120

Infections due

Cryptococcus neoformans

Histoplasma capsulatum

, or

Coccidioides immitis

can occur

in health-care settings if nearby ground is disturbed and a malfunction of the facility’s air-intake

components allows these pathogens to enter the ventilation system.

C. neoformans

is a yeast usually 4–

8 µm in size. However, viable particles of <2 µm diameter (and thus permissive to alveolar deposition)

have been found in soil contaminated with bird droppings, particularly from pigeons.

98, 103, 104, 121

capsulatum

, with the infectious microconidia ranging in size from 2–5 µm, is endemic in the soil of the

central river valleys of the United States. Substantial numbers of these infectious particles have been

associated with chicken coops and the roosts of blackbirds.

98, 103, 104, 122

Several outbreaks of

histoplasmosis have been associated with disruption of the environment; construction activities in an

endemic area may be a potential risk factor for health-care–acquired airborne infection.

123, 124

immitis

, with arthrospores of 3–5 µm diameter, has similar potential, especially in the endemic

southwestern United States and during seasons of drought followed by heavy rainfall. After the 1994

earthquake centered near Northridge, California, the incidence of coccidioidomycosis in the surrounding

area exceeded the historical norm.

125

Emerging evidence suggests that

Pneumocystis carinii

, now classified as a fungus, may be spread via

airborne, person-to-person transmission.

126

Controlled studies in animals first demonstrated that

carinii

could be spread through the air.

127

More recent studies in health-care settings have detected

nucleic acids of

P. carinii

in air samples from areas frequented or occupied by

P. carinii

-infected

patients but not in control areas that are not occupied by these patients.

128, 129

Clusters of cases have

been identified among

immunocompromised patients who had contact with a source patient and

with

each other. Recent studies have examined the presence of

P. carinii

DNA in oropharyngeal washings

and the nares of infected patients, their direct contacts, and persons with no direct contact.

130, 131

Molecular analysis of the DNA by polymerase chain reaction (PCR) provides evidence for airborne

transmission of

P. carinii

from infected patients to direct contacts, but immunocompetent contacts tend

to become transiently colonized rather than infected.

131

The role of colonized persons in the spread of

P. carinii

pneumonia (PCP) remains to be determined. At present, specific modifications to ventilation

systems to control spread of PCP in a health-care facility are not indicated. Current recommendations

outline isolation procedures to minimize or eliminate contact of immunocompromised patients not on

PCP prophylaxis with PCP-infected patients.

6, 132

b. Tuberculosis and Other Bacterial Diseases

The bacterium most commonly associated with airborne transmission is

Mycobacterium tuberculosis

. A

comprehensive review of the microbiology and epidemiology of

M. tuberculosis

and guidelines for

tuberculosis (TB) infection control have been published.

4, 133, 134

A summary of the clinical and

epidemiologic information from these materials is provided in this guideline (Table 3).

Table 3. Clinical and epidemiologic characteristics of tuberculosis (TB)*

Causative agents

Mycobacterium tuberculosis, M. bovis, M. africanum

Mode of transmission

Airborne transmission via droplet nuclei 1–5 µm in diameter

Patient factors associated with

infectivity and transmission

▪

Disease of the lungs, airways, or larynx; presence of cough or other forceful

expiratory measures

▪

Presence of acid-fast bacilli (AFB) in the sputum

▪

Failure of the patient to cover the mouth and nose when coughing or sneezing

▪

Presence of cavitation on chest radiograph

▪

Inappropriate or shortened duration of chemotherapy

Activities associated with

infections

▪

Exposures in relatively small, enclosed spaces

▪

Inadequate ventilation resulting in insufficient removal of droplet nuclei

▪

Cough-producing procedures done in areas without proper environmental controls

▪

Recirculation of air containing infectious droplet nuclei

▪

Failure to use respiratory protection when managing open lesions for patients with

suspected extrapulmonary TB

135

Clinical syndromes and disease

Pulmonary TB

; extrapulmonary TB can affect any organ system or tissue; laryngeal

TB is highly contagious

Populations at greatest risk

▪

Immunocompromised persons (e.g., HIV-infected persons)

▪

Medically underserved persons, urban poor, homeless persons, elderly persons,

migrant farm workers, close contacts of known patients

▪

Substance abusers, present and former prison inmates

▪

Foreign-born persons from areas with high prevalence of TB

▪

Health-care workers

Factors affecting severity and

outcomes

▪

Concentration of droplet nuclei in air, duration of exposure

▪

Age at infection

▪

Immunosuppression due to therapy or disease, underlying chronic medical

conditions, history of malignancies or lesions or the lungs

Occurrence

Worldwide; incidence in the United States is 5.6 cases/100,000 population (2001)

136

Mortality

930 deaths in the United States (1999)

136

Chemoprophylaxis / treatment

Treatment of latent infection includes isoniazid (INH) or rifampin (RIF).

4, 134, 137–139

Directly observed therapy (DOT) for active cases as indicated: INH, RIF,

pyrazinamide (PZA), ethambutol (EMB), streptomycin (SM) in various combinations

determined by prevalent levels of specific resistance.

4, 134, 137–139

Consult therapy

guidelines for specific treatment indications.

139

* Material in this table is compiled from references 4, 133–141.

M. tuberculosis

is carried by droplet nuclei generated when persons (primarily adults and adolescents)

who have pulmonary or laryngeal TB sneeze, cough, speak, or sing;

139

normal air currents can keep

these particles airborne for prolonged periods and spread them throughout a room or building.

142

However, transmission of TB has occurred from mycobacteria aerosolized during provision of care

(e.g., wound/lesion care or during handling of infectious peritoneal dialysis fluid) for extrapulmonary

TB patients.

135, 140

Gram-positive cocci (i.e.,

Staphylococcus aureus

, group A beta-hemolytic streptococci), also important

health-care–associated pathogens, are resistant to inactivation by drying and can persist in the

environment and on environmental surfaces for extended periods. These organisms can be shed from

heavily colonized persons and discharged into the air. Airborne dispersal of

S. aureus

is directly

associated with the concentration of the bacterium in the anterior nares.

143

Approximately 10% of

healthy carriers will disseminate

S. aureus

into the air, and some persons become more effective

disseminators of

S. aureus

than others.

144–148

The dispersal of

S. aureus

into air can be exacerbated by

concurrent viral upper respiratory infection, thereby turning a carrier into a “cloud shedder.”

149

Outbreaks of surgical site infections (SSIs) caused by group A beta-hemolytic streptococci have been

traced to airborne transmission from colonized operating-room personnel to patients.

150–153

In these

situations, the strain causing the outbreak was recovered from the air in the operating room

150, 151, 154

on settle plates in a room in which the carrier exercised.

151–153

S. aureus

and group A streptococci have

not been linked to airborne transmission outside of operating rooms, burn units, and neonatal

nurseries.

155, 156

Transmission of these agents occurs primarily via contact and droplets.

Other gram-positive bacteria linked to airborne transmission include

Bacillus

spp. which are capable of

sporulation as environmental conditions become less favorable to support their growth. Outbreaks and

pseudo-outbreaks have been attributed to

Bacillus cereus

in maternity, pediatric, intensive care, and

bronchoscopy units; many of these episodes were secondary to environmental contamination.

157–160

Gram-negative bacteria rarely are associated with episodes of airborne transmission because they

generally require moist environments for persistence and growth. The main exception is

Acinetobacter

spp., which can withstand the inactivating effects of drying. In one epidemiologic investigation of

bloodstream infections among pediatric patients, identical

Acinetobacter

spp. were cultured from the

patients, air, and room air conditioners in a nursery.

161

Aerosols generated from showers and faucets may potentially contain legionellae and other gram-

negative waterborne bacteria (e.g.,

Pseudomonas aeruginosa

). Exposure to these organisms is through

direct inhalation. However, because water is the source of the organisms and exposure occurs in the

vicinity of the aerosol, the discussion of the diseases associated with such aerosols and the prevention

measures used to curtail their spread is discussed in another section of the Guideline (see Part I: Water).

c. Airborne Viral Diseases

Some human viruses are transmitted from person to person via droplet aerosols, but very few viruses are

consistently airborne in transmission (i.e., are routinely suspended in an infective state in air and capable

of spreading great distances), and health-care–associated outbreaks of airborne viral disease are limited

to a few agents. Consequently, infection-control measures used to prevent spread of these viral diseases

in health-care facilities primarily involve patient isolation, vaccination of susceptible persons, and

antiviral therapy as appropriate rather than measures to control air flow or quality.

Infections caused

by VZV frequently are described in health-care facilities. Health-care–associated airborne outbreaks of

VZV infections from patients with primary infection and disseminated zoster have been documented;

patients with localized zoster have, on rare occasions, also served as source patients for outbreaks in

health-care facilities.

162–166

VZV infection can be prevented by vaccination, although patients who

develop a rash within 6 weeks of receiving varicella vaccine or who develop breakthrough varicella

following exposure should be considered contagious.

167

Viruses whose major mode of transmission is via droplet contact rarely have caused clusters of

infections in group settings through airborne routes. The factors facilitating airborne distribution of

these viruses in an infective state are unknown, but a presumed requirement is a source patient in the

early stage of infection who is shedding large numbers of viral particles into the air. Airborne

transmission of measles has been documented in health-care facilities.

168–171

In addition, institutional

outbreaks of influenza virus infections have occurred predominantly in nursing homes,

172–176

and less

frequently in medical and neonatal intensive care units, chronic-care areas, HSCT units, and pediatric

wards.

177–180

Some evidence supports airborne transmission of influenza viruses by droplet nuclei,

181, 182

and case clusters in pediatric wards suggest that droplet nuclei may play a role in transmitting certain

respiratory pathogens (e.g., adenoviruses and respiratory syncytial virus [RSV]).

177, 183, 184

Some

evidence also supports airborne transmission of enteric viruses. An outbreak of a Norwalk-like virus

infection involving more than 600 staff personnel over a 3-week period was investigated in a Toronto,

Ontario hospital in 1985; common sources (e.g., food and water) were ruled out during the

investigation, leaving airborne spread as the most likely mode of transmission.

185

Smallpox virus, a potential agent of bioterrorism, is spread predominantly via direct contact with

infectious droplets, but it also can be associated with airborne transmission.

186, 187

A German hospital

study from 1970 documented the ability of this virus to spread over considerable distances and cause

infection at low doses in a well-vaccinated population; factors potentially facilitating transmission in

this situation included a patient with cough and an extensive rash, indoor air with low relative humidity,

and faulty ventilation patterns resulting from hospital design (e.g., open windows).

188

Smallpox

patients with extensive rash are more likely to have lesions present on mucous membranes and therefore

have greater potential to disseminate virus into the air.

188

In addition to the smallpox transmission in

Germany, two cases of laboratory-acquired smallpox virus infection in the United Kingdom in 1978

also were thought to be caused by airborne transmission.

189

Airborne transmission may play a role in the natural spread of hantaviruses and certain hemorrhagic

fever viruses (e.g., Ebola, Marburg, and Lassa), but evidence for airborne spread of these agents in

health-care facilities is inconclusive.

190

Although hantaviruses can be transmitted when aerosolized

from rodent excreta,

191, 192

person-to-person spread of hantavirus infection from source patients has not

occurred in health-care facilities.

193–195

Nevertheless, health-care workers are advised to contain

potentially infectious aerosols and wear National Institute of Occupational Safety and Health (NIOSH)

approved respiratory protection when working with this agent in laboratories or autopsy suites.

196

Lassa virus transmission via aerosols has been demonstrated in the laboratory and incriminated in

health-care–associated infections in Africa,

197–199

but airborne spread of this agent in hospitals in

developed nations likely is inefficient.

200, 201

Yellow fever is considered to be a viral hemorrhagic fever

agent with high aerosol infectivity potential, but health-care–associated transmission of this virus has

not been described.

202

Viral hemorrhagic fever diseases primarily occur after direct exposure to

infected blood and body fluids, and the use of standard and droplet precautions prevents transmission

early in the course of these illnesses.

203, 204

However, whether these viruses can persist in droplet nuclei

that might remain after droplet production from coughs or vomiting in the latter stages of illness is

unknown.

205

Although the use of a negative-pressure room is not required during the early stages of

illness, its use might be prudent at the time of hospitalization to avoid the need for subsequent patient

transfer. Current CDC guidelines recommend negative-pressure rooms with anterooms for patients with

hemorrhagic fever and use of HEPA respirators by persons entering these rooms when the patient has

prominent cough, vomiting, diarrhea, or hemorrhage.

6, 203

Face shields or goggles will help to prevent

mucous-membrane exposure to potentially-aerosolized infectious material in these situations. If an

anteroom is not available, portable, industrial-grade high efficiency particulate air (HEPA) filter units

can be used to provide the equivalent of additional air changes per hour (ACH).

Table 4. Microorganisms associated with airborne transmission*

Fungi Bacteria Viruses

Numerous reports
in health-care
facilities

Aspergillus

spp.+

Mucorales

(

Rhizopus

spp.)

97, 115

Mycobacterium
tuberculosis

Measles (rubeola) virus

168-170

Varicella-zoster virus

162-166

Atypical,
occasional reports

Acremonium

spp.

105, 206

Fusarium

spp.

102

Pseudoallescheria boydii

100

Scedosporium

spp.

116

Sporothrix cyanescens

118

Acinetobacter

spp.

161

Bacillus

spp.¶

160, 207

Brucella

spp.**

208-211

Staphylococcus aureus

148, 156

Group A

Streptococcus

151

Smallpox virus (variola)§

188, 189

Influenza viruses

181, 182

Respiratory syncytial virus

183

Adenoviruses

184

Norwalk-like virus

185

Airborne in nature;
airborne
transmission in
health care settings
not described

Coccidioides immitis

125

Cryptococcus

spp.

121

Histoplasma capsulatum

124

Coxiella burnetii

(Q fever)

212

Hantaviruses

193, 195

Lassa virus

205

Marburg virus

205

Ebola virus

205

Crimean-Congo virus

205

Under investigation

Pneumocystis carinii

131

— —

* This list excludes microorganisms transmitted from aerosols derived from water.

+ Refer to the text for references for these disease agents.

§ Airborne transmission of smallpox is infrequent. Potential for airborne transmission increases with patients who are effective disseminators

present in facilities with low relative humidity in the air and faulty ventilation.

¶ Documentation of pseudoepidemic during construction.

** Airborne transmission documented in the laboratory but not in patient-care areas

3. Heating, Ventilation, and Air Conditioning Systems in Health-Care
Facilities

a. Basic Components and Operations

Heating, ventilation, and air conditioning (HVAC) systems in health-care facilities are designed to a)

maintain the indoor air temperature and humidity at comfortable levels for staff, patients, and visitors;

b) control odors; c) remove contaminated air; d) facilitate air-handling requirements to protect

susceptible staff and patients from airborne health-care–associated pathogens; and e) minimize the risk

for transmission of airborne pathogens from infected patients.

35, 120

An HVAC system includes an

outside air inlet or intake; filters; humidity modification mechanisms (i.e., humidity control in summer,

humidification in winter); heating and cooling equipment; fans; ductwork; air exhaust or out-takes; and

registers, diffusers, or grilles for proper distribution of the air (Figure 1).

213, 214

Decreased performance

of healthcare facility HVAC systems, filter inefficiencies, improper installation, and poor maintenance

can contribute to the spread of health-care–associated airborne infections.

The American Institute of Architects (AIA) has published guidelines for the design and construction of

new health-care facilities and for renovation of existing facilities. These AIA guidelines address indoor

air-quality standards (e.g., ventilation rates, temperature levels, humidity levels, pressure relationships,

and minimum air changes per hour [ACH]) specific to each zone or area in health-care facilities (e.g.,

operating rooms, laboratories, diagnostic areas, patient-care areas, and support departments).

120

These

guidelines represent a consensus document among authorities having jurisdiction (AHJ), governmental

regulatory agencies (i.e., Department of Health and Human Services [DHHS]; Department of Labor,

Occupational Safety and Health Administration [OSHA]), health-care professionals, professional

organizations (e.g., American Society of Heating, Refrigeration, and Air-Conditioning Engineers

[ASHRAE], American Society for Healthcare Engineering [ASHE]), and accrediting organizations (i.e.,

Joint Commission on Accreditation of Healthcare Organizations [JCAHO]). More than 40 state

agencies that license health-care facilities have either incorporated or adopted

by reference these

guidelines

into their state standards. JCAHO, through its surveys, ensures that facilities are in

compliance with the ventilation guidelines of this standard for new construction and renovation.

Figure 1. Diagram of a ventilation system*

Outdoor air and recirculated air pass through air cleaners (e.g., filter banks) designed to reduce the concentration of airborne

contaminants. Air is conditioned for temperature and humidity before it enters the occupied space as supply air. Infiltration is

air leakage inward through cracks and interstitial spaces of walls, floors, and ceilings. Exfiltration is air leakage outward

through these same cracks and spaces. Return air is largely exhausted from the system, but a portion is recirculated with fresh,

incoming air.

* Used with permission of the publisher of reference 214 (ASHRAE)

Engineering controls to contain or prevent the spread of airborne contaminants center on a) local

exhaust ventilation [i.e., source control], b) general ventilation, and c) air cleaning.

General ventilation

encompasses a) dilution and removal of contaminants via well-mixed air distribution of filtered air, b)

directing contaminants toward exhaust registers and grilles via uniform, non-mixed airflow patterns, c)

pressurization of individual spaces relative to all other spaces, and d) pressurization of buildings relative

to the outdoors and other attached buildings.

A centralized HVAC system operates as follows. Outdoor air enters the system, where low-efficiency

or “roughing” filters remove large particulate matter and many microorganisms. The air enters the

distribution system for conditioning to appropriate temperature and humidity levels, passes through an

additional bank of filters for further cleaning, and is delivered to each zone of the building. After the

conditioned air is distributed to the designated space, it is withdrawn through a return duct system and

delivered back to the HVAC unit. A portion of this “return air” is exhausted to the outside while the

remainder is mixed with outdoor air for dilution and filtered for removal of contaminants.

215

Air from

toilet rooms or other soiled areas is usually exhausted directly to the atmosphere through a separate duct

exhaust system. Air from rooms housing tuberculosis patients is exhausted to the outside if possible, or

passed through a HEPA filter before recirculation. Ultraviolet germicidal irradiation (UVGI) can be

used as an adjunct air-cleaning measure, but it cannot replace HEPA filtration.

b. Filtration

i. Filter Types and Methods of Filtration

Filtration, the physical removal of particulates from air, is the first step in achieving acceptable indoor

air quality. Filtration is the primary means of cleaning the air. Five methods of filtration can be used

(Table 5). During filtration, outdoor air passes through two filter beds or banks (with efficiencies of

20%–40% and >90%, respectively) for effective removal of particles 1–5 µm in diameter.

35, 120

The

low-to-medium efficiency filters in the first bank have low resistance to airflow, but this feature allows

some small particulates to pass onto heating and air conditioning coils and into the indoor

environment.

Incoming air is mixed with recirculated air and reconditioned for temperature and

humidity before being filtered by the second bank of filters. The performance of filters with <90%

efficiency is measured using either the dust-spot test or the weight-arrestance test.

35, 216

Table 5. Filtration methods*

Basic method

Principle of performance Filtering

efficiency

Straining

Particles in the air are larger than the openings between the

filter fibers, resulting in gross removal of large particles.

Low

Impingement

Particles collide with filter fibers and remain attached to the

filter. Fibers may be coated with adhesive.

Low

Interception

Particles enter into the filter and become entrapped and

attached to the filter fibers.

Medium

Diffusion

Small particles, moving in erratic motion, collide with filter

fibers and remain attached.

High

Electrostatic

Particles bearing negative electrostatic charge are attracted to

the filter with positively charged fibers.

High

* Material in this table was compiled from information in reference 217.

The second filter bank usually consists of high-efficiency filters. This filtration system is adequate for

most patient-care areas in ambulatory-care facilities and hospitals, including the operating room

environment and areas providing central services.

120

Nursing facilities use 90% dust-spot efficient

filters as the second bank of filters,

120

whereas a HEPA filter bank may be indicated for special-care

areas of hospitals. HEPA filters are at least 99.97% efficient for removing particles >0.3 µm in

diameter. (As a reference,

Aspergillus

spores are 2.5–3.0 µm in diameter.) Examples of care areas

where HEPA filters are used include PE rooms and those operating rooms designated for orthopedic

implant procedures.

Maintenance costs associated with HEPA filters are high compared with other types of filters, but use of

in-line disposable prefilters can increase the life of a HEPA filter by approximately 25%. Alternatively,

if a disposable prefilter is followed by a filter that is 90% efficient, the life of the HEPA filter can be

extended ninefold. This concept, called progressive filtration, allows HEPA filters in special care areas

to be used for



10 years.

213

Although progressive filtering will extend the mechanical ability of the

HEPA filter, these filters may absorb chemicals in the environment and later desorb those chemicals,

thereby necessitating a more frequent replacement program. HEPA filter efficiency is monitored with

the dioctylphthalate (DOP) particle test using particles that are 0.3 µm in diameter.

218

HEPA filters are usually framed with metal, although some older versions have wood frames. A metal

frame has no advantage over a properly fitted wood frame with respect to performance, but wood can

compromise the air quality if it becomes and remains wet, allowing the growth of fungi and bacteria.

Hospitals are therefore advised to phase out water-damaged or spent wood-framed filter units and

replace them with metal-framed HEPA filters.

HEPA filters are usually fixed into the HVAC system; however, portable, industrial grade HEPA units

are available that can filter air at the rate of 300–800 ft

/min. Portable HEPA filters are used to a)

temporarily recirculate air in rooms with no general ventilation, b) augment systems that cannot provide

adequate airflow, and c) provide increased effectiveness in airflow.

Portable HEPA units are useful

engineering controls that help clean the air when the central HVAC system is undergoing repairs,

219

but

these units do not satisfy fresh-air requirements.

214

The effectiveness of the portable unit for particle

removal is dependent on a) the configuration of the room, b) the furniture and persons in the room, c)

the placement of the units relative to the contents and layout of the room, and d) the location of the

supply and exhaust registers or grilles. If portable, industrial-grade units are used, they should be

capable of recirculating all or nearly all of the room air through the HEPA filter, and the unit should be

designed to achieve the equivalent of >12 ACH.

(An average room has approximately 1,600 ft

airspace.) The hospital engineering department should be contacted to provide ACH information in the

event that a portable HEPA filter unit is necessary to augment the existing fixed HVAC system for

air

cleaning.

ii. Filter Maintenance

Efficiency of the filtration system is dependent on the density of the filters, which can create a drop in

pressure unless compensated by stronger and more efficient fans, thus maintaining air flow. For optimal

performance, filters require monitoring and replacement in accordance with the manufacturer’s

recommendations and standard preventive maintenance practices.

220

Upon removal, spent filters can be

bagged and discarded with the routine solid waste, regardless of their patient-care area location.

221

Excess accumulation of dust and particulates increases filter efficiency, requiring more pressure to push

the air through. The pressure differential across filters is measured by use of manometers or other

gauges. A pressure reading that exceeds specifications indicates the need to change the filter. Filters

also require regular inspection for other potential causes of decreased performance. Gaps in and around

filter banks and heavy soil and debris upstream of poorly maintained filters have been implicated in

health-care–associated outbreaks of aspergillosis, especially when accompanied by construction

activities at the facility.

17, 18, 106, 222

c. Ultraviolet Germicidal Irradiation (UVGI)

As a supplemental air-cleaning measure, UVGI is effective in reducing the transmission of airborne

bacterial and viral infections in hospitals, military housing, and classrooms, but it has only a minimal

inactivating effect on fungal spores.

223–228

UVGI is also used in air handling units to prevent or limit

the growth of vegetative bacteria and fungi. Most commercially available UV lamps used for

germicidal purposes are low-pressure mercury vapor lamps that emit radiant energy predominantly at a

wave-length of 253.7 nm.

229, 230

Two systems of UVGI have been used in health-care settings – duct

irradiation and upper-room air irradiation. In duct irradiation systems, UV lamps are placed inside ducts

that remove air from rooms to disinfect the air before it is recirculated. When properly designed,

installed, and maintained, high levels of UVGI can be attained in the ducts with little or no exposure of

persons in the rooms.

231, 232

In upper-room air irradiation, UV lamps are either suspended from the

ceiling or mounted on the wall.

Upper air UVGI units have two basic designs: a) a “pan” fixture with

UVGI unshielded above the unit to direct the irradiation upward and b) a fixture with a series of parallel

plates to columnize the irradiation outward while preventing the light from getting to the eyes of the

room’s occupants. The germicidal effect is dependent on air mixing via convection between the room’s

irradiated upper zone and the lower patient-care zones.

233, 234

Bacterial inactivation studies using BCG mycobacteria and

Serratia marcescens

have estimated the

effect of UVGI as equivalent to 10 ACH–39 ACH.

235, 236

Another study, however, suggests that UVGI

may result in fewer equivalent ACH in the patient-care zone, especially if the mixing of air between

zones is insufficient.

234

The use of fans or HVAC systems to generate air movement may increase the

effectiveness of UVGI if airborne

microorganisms are exposed to the light energy for a sufficient

length

of time.

233, 235, 237–239

The optimal relationship between ventilation and UVGI is not known.

Because the clinical effectiveness of UV systems may vary, UVGI is not recommended for air

management prior to air recirculation from airborne isolation rooms. It is also not recommended as a

substitute for HEPA filtration, local exhaust of air to the outside, or negative pressure.

The use of UV

lamps and HEPA filtration in a single unit offers only minimal infection-control benefits over those

provided by the use of a HEPA filter alone.

240

Duct systems with UVGI are not recommended as a

substitute for HEPA filters if the air from isolation rooms must be recirculated to other areas of the

facility.

Regular maintenance of UVGI systems is crucial and usually consists of keeping the bulbs

free of dust and replacing old bulbs as necessary. Safety issues associated with the use of UVGI

systems are described in other guidelines.

d. Conditioned Air in Occupied Spaces

Temperature and humidity are two essential components of conditioned air. After outside air passes

through a low- or medium-efficiency filter, the air undergoes conditioning for temperature and humidity

control before it passes through high-efficiency or HEPA filtration.

i. Temperature

HVAC systems in health-care facilities are often single-duct or dual-duct systems.

35, 241

A single-duct

system distributes cooled air (55°F [12.8°C]) throughout the building and uses thermostatically

controlled reheat boxes located in the terminal ductwork to warm the air for individual or multiple

rooms. The dual-duct system consists of parallel ducts, one with a cold air stream and the other with a

hot air stream. A mixing box in each room or group of rooms mixes the two air streams to achieve the

desired temperature. Temperature standards are given as either a single temperature or a range,

depending on the specific health-care zone. Cool temperature standards (68°F–73°F [20°C–23°C])

usually are associated with operating rooms, clean workrooms, and endoscopy suites.

120

A warmer

temperature (75°F [24°C]) is needed in areas requiring greater degrees of patient comfort. Most other

zones use a temperature range of 70°F–75°F (21°C–24°C).

120

Temperatures outside of these ranges

may be needed occasionally in limited areas depending on individual circumstances during patient care

(e.g., cooler temperatures in operating rooms during specialized operations).

ii. Humidity

Four measures of humidity are used to quantify different physical properties of the mixture of water

vapor and air. The most common of these is relative humidity, which is the ratio of the amount of water

vapor in the air to the amount of water vapor air can hold at that temperature.

242

The other measures of

humidity are specific humidity, dew point, and vapor pressure.

242

Relative humidity measures the percentage of saturation. At 100% relative humidity, the air is

saturated. For most areas within health-care facilities, the designated comfort range is 30%–60%

relative humidity.

120, 214

Relative humidity levels >60%, in addition to being perceived as

uncomfortable, promote fungal growth.

243

Humidity levels can be manipulated by either of two

mechanisms.

244

In a water-wash unit, water is sprayed and drops are taken up by the filtered air;

additional heating or cooling of this air sets the humidity levels. The second mechanism is by means of

water vapor created from steam and added to filtered air in humidifying boxes. Reservoir-type

humidifiers are not allowed in health-care facilities as per AIA guidelines and many state codes.

120

Cool-mist humidifiers should be avoided, because they can disseminate aerosols containing allergens

and microorganisms.

245

Additionally, the small, personal-use versions of this equipment can be

difficult to clean.

iii. Ventilation

The control of air pollutants (e.g., microorganisms, dust, chemicals, and smoke) at the source is the most

effective way to maintain clean air. The second most effective means of controlling indoor air pollution

is through ventilation. Ventilation rates are voluntary unless a state or local government specifies a

standard in health-care licensing or health department requirements. These standards typically apply to

only the design of a facility, rather than its operation.

220, 246

Health-care facilities without specific

ventilation standards should follow the AIA guideline specific to the year in which the building was

built or the ANSI/ASHRAE Standard 62,

Ventilation for Acceptable Indoor Air Quality

120, 214, 241

Ventilation guidelines are defined in terms of air volume per minute per occupant and are based on the

assumption that occupants and their activities are responsible for most of the contaminants in the

conditioned space.

215

Most ventilation rates for health-care facilities are expressed as room ACH. Peak

efficiency for particle removal in the air space occurs between 12 ACH–15 ACH.

35, 247, 248

Ventilation

rates vary among the different patient-care areas of a health-care facility (Appendix B).

120

Health-care facilities generally use recirculated air.

35, 120, 241, 249, 250

Fans create sufficient positive

pressure to force air through the building duct work and adequate negative pressure to evacuate air from

the conditioned space into the return duct work and/or exhaust, thereby completing the circuit in a

sealed system (Figure 1). However, because gaseous contaminants tend to accumulate as the air

recirculates, a percentage of the recirculated air is exhausted to the outside and replaced by fresh

outdoor air. In hospitals, the delivery of filtered air to an occupied space is an engineered system design

issue, the full discussion of which is beyond the scope of this document.

Hospitals with areas not served by central HVAC systems often use through-the-wall or fan coil air

conditioning units as the sole source of room ventilation. AIA guidelines for newly installed systems

stipulate that through-the-wall fan-coil units be equipped with permanent (i.e., cleanable) or replaceable

filters with a minimum efficiency of 68% weight arrestance.

120

These units may be used only as

recirculating units; all outdoor air requirements must be met by a separate central air handling system

with proper filtration, with a minimum of two outside air changes in general patient rooms (D. Erickson,

ASHE, 2000).

120

If a patient room is equipped with an individual through-the-wall fan coil unit, the

room should not be used as either AII or as PE.

120

These requirements, although directed to new

HVAC installations also are appropriate for existing settings. Non-central air-handling systems are

prone to problems associated with excess condensation accumulating in drip pans and improper filter

maintenance; health-care facilities should clean or replace the filters in these units on a regular basis

while the patient is out of the room.

Laminar airflow ventilation systems are designed to move air in a single pass, usually through a bank of

HEPA filters either along a wall or in the ceiling, in a one-way direction through a clean zone with

parallel streamlines. Laminar airflow can be directed vertically or horizontally; the unidirectional

system optimizes airflow and minimizes air turbulence.

63, 241

Delivery of air at a rate of 0.5 meters per

second (90 + 20 ft/min) helps to minimize opportunities for microorganism proliferation.

63, 251, 252

Laminar airflow systems have been used in PE to help reduce the risk for health-care–associated

airborne infections (e.g., aspergillosis) in high-risk patients.

63, 93, 253, 254

However, data that demonstrate

a survival benefit for patients in PE with laminar airflow are lacking. Given the high cost of installation

and apparent lack of benefit, the value of laminar airflow in this setting is questionable.

9, 37

Few data

support the use of laminar airflow systems elsewhere in a hospital.

255

iv. Pressurization

Positive and negative pressures refer to a pressure differential between two adjacent air spaces (e.g.,

rooms and hallways). Air flows away from areas or rooms with positive pressure (pressurized),

while

air flows into

areas with negative pressure (depressurized). AII rooms are set at negative pressure to

prevent airborne microorganisms in the room from entering hallways and corridors. PE rooms housing

severely neutropenic patients are set at positive pressure to keep airborne pathogens in adjacent spaces

or corridors from coming into and contaminating the airspace occupied by such high-risk patients. Self-

closing doors are mandatory for both of these areas to help maintain the correct pressure differential.

4, 6,

120

Older health-care facilities may have variable pressure rooms (i.e., rooms in which the ventilation

can be manually switched between positive and negative pressure). These rooms are no longer

permitted in the construction of new facilities or in renovated areas of the facility,

120

and their use in

existing facilities has been discouraged because of difficulties in assuring the proper pressure

differential, especially for the negative pressure setting, and because of the potential for error associated

with switching the pressure differentials for the room. Continued use of existing variable pressure

rooms depends on a partnership between engineering and infection control. Both positive- and

negative-pressure rooms should be maintained according to specific engineering specifications (Table

6).

Table 6. Engineered specifications for positive- and negative pressure rooms*

Positive pressure areas (e.g.,

protective environments [PE])

Negative pressure areas (e.g.,

airborne infection isolation [AII])

Pressure differentials

> +2.5 Pa§ (0.01

″

water gauge)

> -2.5 Pa (0.01

″

water gauge)

Air changes per hour (ACH)

>12 >12 (for renovation or new construction)

Filtration efficiency

Supply: 99.97% @ 0.3 µm DOP¶

Return: none required**

Supply: 90% (dust spot test)

Return: 99.97% @ 0.3 µm DOP¶

Room airflow direction

Out to the adjacent area

In to the room

Clean-to-dirty airflow in

room

Away from the patient (high-risk patient,

immunosuppressed patient)

Towards the patient (airborne disease

patient)

Ideal pressure differential

> + 8 Pa

> - 2.5 Pa

* Material in this table was compiled from references 35 and 120. Table adapted from and used with permission of the publisher of reference

35 (Lippincott Williams and Wilkins).

§ Pa is the abbreviation for Pascal, a metric unit of measurement for pressure based on air velocity; 250 Pa equals 1.0 inch water gauge.

¶ DOP is the abbreviation for dioctylphthalate particles of 0.3 µm diameter.

** If the patient requires both PE and AII, return air should be HEPA-filtered or otherwise exhausted to the outside.

HEPA filtration of exhaust air from AII rooms should not be required, providing that the exhaust is properly located to prevent re-entry into

the building.

Health-care professionals (e.g., infection control, hospital epidemiologists) must perform a risk

assessment to determine the appropriate number of AII rooms (negative pressure) and/or PE rooms

(positive pressure) to serve the patient population. The AIA guidelines require a certain number of AII

rooms as a minimum, and it is important to refer to the edition under which the building was built for

appropriate guidance.

120

In large health-care facilities with central HVAC systems, sealed windows help to ensure the efficient

operation of the system, especially with respect to creating and maintaining pressure differentials.

Sealing the windows in PE areas helps minimize the risk of airborne contamination from the outside.

One outbreak of aspergillosis among immunosuppressed patients in a hospital was attributed in part to

an open window in the unit during a time when both construction and a fire happened nearby; sealing

the window prevented further entry of fungal spores into the unit from the outside air.

111

Additionally,

all emergency exits (e.g., fire escapes and emergency doors) in PE wards should be kept closed (except

during emergencies) and equipped with alarms.

e. Infection Control Impact of HVAC System Maintenance and Repair

A failure or malfunction of any component of the HVAC system may subject patients and staff to

discomfort and exposure to airborne contaminants. Only limited information is available from formal

studies on the infection-control implications of a complete air-handling system

failure or shutdown for

maintenance. Most experience has been derived from infectious disease outbreaks and adverse

outcomes among high-risk patients when HVAC systems are poorly maintained. (See Table 7 for

potential ventilation hazards, consequences, and correction measures.)

AIA guidelines prohibit U.S. hospitals and surgical centers from shutting down their HVAC systems for

purposes other than required maintenance, filter changes, and construction.

120

Airflow can be reduced;

however, sufficient supply, return, and exhaust must be provided to maintain required pressure

relationships when the space is not occupied. Maintaining these relationships can be accomplished with

special drives on the air-handling units (i.e., a variable air ventilation [VAV] system).

Microorganisms proliferate in environments wherever air, dust, and water are present, and air-handling

systems can be ideal environments for microbial growth.

Properly engineered HVAC systems require

routine maintenance and monitoring to provide acceptable indoor air quality efficiently and to minimize

conditions that favor the proliferation of health-care–associated pathogens.

35, 249

Performance

monitoring of the system includes determining pressure differentials across filters, regular inspection of

system filters, DOP testing of HEPA filters, testing of low- or medium efficiency filters, and manometer

tests for positive- and negative-pressure areas in accordance with nationally recognized standards,

guidelines, and manufacturers’ recommendations. The use of hand-held, calibrated equipment that can

provide a numerical reading on a daily basis is preferred for engineering purposes (A.Streifel,

University of Minnesota, 2000).

256

Several methods that provide a visual, qualitative measure of

pressure differentials (i.e., airflow direction) include smoke-tube tests or placing flutter strips, ping-pong

balls, or tissue in the air stream.

Preventive filter and duct maintenance (e.g., cleaning ductwork vents, replacing filters as needed, and

properly disposing spent filters into plastic bags immediately upon removal) is important to prevent

potential exposures of patients and staff during HVAC system shut-down. The frequency of filter

inspection and the parameters of this inspection are established by each facility to meet their unique

needs. Ductwork in older health-care facilities may have insulation on the interior surfaces that can trap

contaminants. This insulation material tends to break down over time to be discharged from the HVAC

system. Additionally, a malfunction of the air-intake system can overburden the filtering system and

permit aerosolization of fungal pathogens. Keeping the intakes free from bird droppings, especially

those from pigeons, helps to minimize the concentration of fungal spores entering from the outside.

Accumulation of dust and moisture within HVAC systems increases the risk for spread of health-care–

associated environmental fungi and bacteria. Clusters of infections caused by

Aspergillus

spp.,

aeruginosa, S. aureus,

and

Acinetobacter

spp. have been linked to poorly maintained and/or

malfunctioning air conditioning systems.

68, 161, 257, 258

Efforts to limit excess humidity and moisture in

the infrastructure and on air-stream surfaces in the HVAC system can minimize the proliferation and

dispersion of fungal spores and waterborne bacteria throughout indoor air.

259–262

Within the HVAC

system, water is present in water-wash units, humidifying boxes, or cooling units. The dual-duct system

may also create conditions of high humidity and excess moisture that favor fungal growth in drain pans

as well as in fibrous insulation material that becomes damp as a result of the humid air passing over the

hot stream and condensing.

If moisture is present in the HVAC system, periods of stagnation should be avoided. Bursts of

organisms can be released upon system start-up, increasing the risk of airborne infection.

206

Proper

engineering of the HVAC system is critical to preventing dispersal of airborne organisms. In one

hospital, endophthalmitis caused by

Acremonium kiliense

infection following cataract extraction in an

ambulatory surgical center was traced to aerosols derived from the humidifier water in the ventilation

system.

206

The organism proliferated because the ventilation system was turned off routinely when the

center was not in operation; the air was filtered before humidification, but not afterwards.

Most health-care facilities have contingency plans in case of disruption of HVAC services. These plans

include back-up power generators that maintain the ventilation system in high-risk areas (e.g., operating

rooms, intensive-care units, negative- and positive-pressure rooms, transplantation units, and oncology

units). Alternative generators are required to engage within 10 seconds of a loss of main power. If the

ventilation system is out of service, rendering indoor air stagnant, sufficient time must be allowed to

clean the air and re-establish the appropriate number of ACH once the HVAC system begins to function

again. Air filters may also need to be changed, because reactivation of the system can dislodge

substantial amounts of dust and create a transient burst of fungal spores.

Duct cleaning in health-care facilities has benefits in terms of system performance, but its usefulness for

infection control has not been conclusively determined. Duct cleaning typically involves using

specialized tools to dislodge dirt and a high-powered vacuum cleaner to clean out debris.

263

Some duct-

cleaning services also apply chemical biocides or sealants to the inside surfaces of ducts to minimize

fungal growth and prevent the release of particulate matter. The U.S. Environmental Protection Agency

(EPA), however, has concerns with the use of sanitizers and/or disinfectants to treat the surfaces of

ductwork, because the label indications for most of these products may not specifically include the use

of the product in HVAC systems.

264

Further, EPA has not evaluated the potency of disinfectants in

such applications, nor has the agency examined the potential attendant health and safety risks. The EPA

recommends that companies use only those chemical biocides that are registered for use in HVAC

systems.

264

Although infrequent cleaning of the exhaust ducts in AII areas has been documented as a

cause of diminishing negative pressure and a decrease in the air exchange rates,

214

no data indicate that

duct cleaning, beyond what is recommended for optimal performance, improves indoor air quality or

reduces the risk of infection. Exhaust return systems should be cleaned as part of routine system

maintenance. Duct cleaning has not been shown to prevent any health problems,

265

and EPA studies

indicate that airborne particulate levels do not increase as a result of dirty air ducts, nor do they diminish

after cleaning, presumably because much of the dirt inside air ducts adheres to duct surfaces and does

not enter the conditioned space.

265

Additional research is needed to determine if air-duct contamination

can significantly increase the airborne infection risk in general areas of health-care facilities.

4. Construction, Renovation, Remediation, Repair, and Demolition

a. General Information

Environmental disturbances caused by construction and/or renovation and repair activities (e.g.,

disruption of the above-ceiling area, running cables through the ceiling, and structural repairs) in and

near health-care facilities markedly increase the airborne

Aspergillus

spp. spore counts in the indoor air

of such facilities, thereby increasing the risk for health-care–associated aspergillosis among high-risk

patients. Although one case of health-care–associated aspergillosis is often difficult to link to a specific

environmental exposure, the occurrence of temporarily clustered cases increase the likelihood that an

environmental source within the facility may be identified and corrected.

Table 7. Ventilation hazards in health-care facilities that may be associated with
increased potential of airborne disease transmission*

Problem§ Consequences

Possible

solutions

Water-damaged building materials (18,

266)

Water leaks can soak wood, wall board,

insulation, wall coverings, ceiling tiles,

and carpeting. All of these materials

can provide microbial habitat when wet.

This is especially true for fungi growing

on gypsum board.

1. Replace water-damaged materials.

2. Incorporate fungistatic compounds

into building materials in areas at

risk for moisture problems.

3. Test for all moisture and dry in less

than 72 hours. Replace if the

material cannot dry within 72

hours.

Filter bypasses (17)

Rigorous air filtration requires air flow

resistance. Air stream will elude

filtration if openings are present because

of filter damage or poor fit.

1. Use pressure gauges to ensure that

filters are performing at proper

static pressure.

2. Make ease of installation and

maintenance criteria for filter

selection.

3. Properly train maintenance personnel

in HVAC concerns.

4. Design system with filters down-

stream from fans.

5. Avoid water on filters or insulation.

Improper fan setting (267)

Air must be delivered at design voume

to maintain pressure balances. Air flow

in special vent rooms reverses.

1. Routinely monitor air flow and

pressure balances throughout

critical parts of HVAC system.

2. Minimize or avoid using rooms that

switch between positive and

negative pressure.

Ductwork disconnections (268)

Dislodged or leaky supply duct runs can

spill into and leaky returns may draw

from hidden areas. Pressure balance

will be interrupted, and infectious

material may be disturbed and entrained

into hospital air supply.

1. Design a ductwork system that is

easy to access, maintain, and repair.

2. Train maintenance personnel to

regularly monitor air flow volumes

and pressure balances throughout

the system.

3. Test critical areas for appropriate

air flow

Air flow impedance (213)

Debris, structural failure, or improperly

adjusted dampers can block duct work

and prevent designed air flow.

1. Design and budget for a duct system

that is easy to inspect, maintain, and

repair.

2. Alert contractors to use caution when

working around HVAC systems

during the construction phase.

3. Regularly clean exhaust grilles.

4. Provide monitoring for special

ventilation areas.

Open windows (96, 247)

Open windows can alter fan-induced

pressure balance and allow dirty-to-

clean air flow.

1. Use sealed windows.

2. Design HVAC systems to deliver

sufficient outdoor dilution

ventilation.

3. Ensure that OSHA indoor air quality

standards are met.

Dirty window air conditioners (96, 269) Dirt, moisture, and bird droppings can

contaminate window air conditioners,

which can then introduce infectious

material into hospital rooms.

1. Eliminate such devices in plans for

new construction.

2. Where they must be used, make sure

that they are routinely cleaned and

inspected.

Problem§

Consequences

Possible solutions

Inadequate filtration (270)

Infectious particles may pass through

filters into vulnerable patient areas.

1. Specify appropriate filters during

new construction design phase.

2. Make sure that HVAC fans are sized

to overcome pressure demands of

filter system.

3. Inspect and test filters for proper

installation.

Maintenance disruptions (271)

Fan shut-offs, dislodged filter cake

material contaminates downstream air

supply and drain pans. This may

compromise air flow in special

ventilation areas.

1. Budget for a rigorous maintenance

schedule when designing a facility.

2. Design system for easy maintenance.

3. Ensure communication between

engineering and maintenance

personnel.

4. Institute an ongoing training program

for all involved staff members.

Excessive moisture in the HVAC

system (120)

Chronically damp internal lining of the

HVAC system, excessive condensate,

and drip pans with stagnant water may

result from this problem.

1. Locate duct humidifiers upstream of

the final filters.

2. Identify a means to remove water

from the system.

3. Monitor humidity; all duct take-offs

should be downstream of the

humidifiers so that moisture is

absorbed completely.

4. Use steam humidifiers in the HVAC

system.

Duct contamination (18, 272)

Debris is released during maintenance

or cleaning.

1. Provide point-of-use filtration in the

critical areas.

2. Design air-handling systems with

insulation of the exterior of the

ducts.

3. Do not use fibrous sound attenuators.

4. Decontaminate or encapsulate

contamination.

* Reprinted with permission of the publisher of reference 35 (Lippincott Williams and Wilkins).

§ Numbers in parentheses are reference citations.

Construction, renovation, repair, and demolition activities in health-care facilities require substantial

planning and coordination to minimize the risk for airborne infection both during projects and after their

completion. Several organizations and experts have endorsed a multi-disciplinary team approach (Box

4) to coordinate the various stages of construction activities (e.g., project inception, project

implementation, final walk-through, and completion).

120, 249, 250, 273–276

Environmental services,

employee health, engineering, and infection control must be represented in construction planning and

design meetings should be convened with architects and design engineers. The number of members and

disciplines represented is a function of the complexity of a project. Smaller, less complex projects and

maintenance may require a minimal number of members beyond the core representation from

engineering, infection control, environmental services, and the directors of the specialized departments.

Box 4. Suggested members and functions of a multi-disciplinary coordination team for
construction, renovation, repair, and demolition projects

Members

Infection-control personnel, including hospital epidemiologists

Laboratory

personnel

Facility administrators or their designated representatives, facility managers

Director

engineering

Risk-management

personnel

Directors of specialized programs (e.g., transplantation, oncology and ICU* programs)

Employee safety personnel, industrial hygienists, and regulatory affairs personnel

Environmental services personnel

Information systems personnel

Construction

administrators

or their designated representatives

Architects, design engineers, project managers, and contractors

Functions and responsibilities

Coordinate members’ input in developing a comprehensive project management plan.

Conduct a risk assessment of the project to determine potential hazards to susceptible patients.

Prevent unnecessary exposures of patients, visitors, and staff to infectious agents.

Oversee all infection-control aspects of construction activities.

Establish site-specific infection-control protocols for specialized areas.

Provide education about the infection-control impact of construction to staff and construction

workers.

Ensure compliance with technical standards, contract provisions, and regulations.

Establish a mechanism to address and correct problems quickly.

Develop contingency plans for emergency response to power failures, water supply disruptions,

and fires.

Provide a water-damage management plan (including drying protocols) for handling water

intrusion from floods, leaks, and condensation.

Develop a plan for structural maintenance.

* ICU is intensive care unit.

Education of maintenance and construction workers, health-care staff caring for high-risk patients, and

persons responsible for controlling indoor air quality heightens awareness that minimizing dust and

moisture intrusion from construction sites into high-risk patient-care areas helps to maintain a safe

environment.

120, 250, 271, 275–278

Visual and printed educational materials should be provided in the

language spoken by the workers. Staff and construction workers also need to be aware of the potentially

catastrophic consequences of dust and moisture intrusion when an HVAC system or water system fails

during construction or repair; action plans to deal quickly with these emergencies should be developed

in advance and kept on file. Incorporation of specific standards into construction contracts may help to

prevent departures from recommended practices as projects progress. Establishing specific lines of

communication is important to address problems (e.g., dust control, indoor air quality, noise levels, and

vibrations), resolve complaints, and keep projects moving toward completion. Health-care facility staff

should develop a mechanism to monitor worker adherence to infection-control guidelines on a daily

basis in and around the construction site for the duration of the project.

b. Preliminary Considerations

The three major topics to consider before initiating any construction or repair activity are as follows: a)

design and function of the new structure or area, b) assessment of environmental risks for airborne

disease and opportunities for prevention, and c) measures to contain dust and moisture during

construction or repairs. A checklist of design and function considerations can help to ensure that a

planned structure or area can be easily serviced and maintained for environmental infection control (Box

5) .

17, 250, 273, 275–277

Specifications for the construction, renovation, remodeling, and maintenance of

health-care facilities are outlined in the AIA document

Guidelines for Design and Construction of

Hospitals and Health Care Facilities

120, 275

Box 5. Construction design and function considerations for environmental infection
control

Location of sinks and dispensers for handwashing products and hand hygiene products

Types of faucets (e.g., aerated vs. non-aerated)

Air-handling

systems

engineered for optimal performance, easy maintenance, and repair

ACH and pressure differentials to accommodate special patient-care areas

Location of fixed sharps containers

Types of surface finishes (e.g., porous vs. non-porous)

Well-caulked walls with minimal seams

Location of adequate storage and supply areas

Appropriate location of medicine preparations areas (e.g., >3 ft. from a sink)

Appropriate location and type of ice machines (e.g., preferably ice dispensers rather than ice bins)

Appropriate

materials

for sinks and wall coverings

Appropriate traffic flow (e.g., no “dirty” movement through “clean” areas)

Isolation rooms with anterooms as appropriate

Appropriate flooring (e.g., seamless floors in dialysis units)

Sensible use carpeting (e.g., avoiding use of carpeting in special care areas or areas likely to become

wet)*

Convenient location of soiled utility areas

Properly engineered areas for linen services and solid waste management

Location of main generator to minimize the risk of system failure from flooding or other emergency

Installation guidelines for sheetrock

* Use of carpet cleaning methods (e.g., “bonneting”) that disperse microorganisms into the air may increase the risk of airborne infection

among at-risk patients, especially if they are in the vicinity of the cleaning activity.

111

Proactive strategies can help prevent environmentally mediated airborne infections in health-care

facilities during demolition, construction, and renovation. The potential presence of dust and moisture

and their contribution to health-care–associated infections must be critically evaluated early in the

planning of any demolition, construction, renovation, and repairs.

120, 250, 251, 273, 274, 276–279

Consideration

must extend beyond dust generated by major projects to include dust that can become airborne if

disturbed during routine maintenance and minor renovation activities (e.g., exposure of ceiling spaces

for inspection; installation of conduits, cable, or sprinkler systems; rewiring; and structural repairs or

replacement).

273, 276, 277

Other projects that can compromise indoor air quality include construction and

repair jobs that inadvertently allow substantial amounts of raw, unfiltered outdoor air to enter the facility

(e.g., repair of elevators and elevator shafts) and activities that dampen any structure, area, or item made

of porous materials or characterized by cracks and crevices (e.g., sink cabinets in need of repair, carpets,

ceilings, floors, walls, vinyl wall coverings, upholstery, drapes, and countertops).

18, 273, 277

Molds grow

and proliferate on these surfaces when they become and remain wet.

21, 120, 250, 266, 270, 272, 280

Scrubbable

materials are preferred for use in patient-care areas.

Containment measures for dust and/or moisture control are dictated by the location of the construction

site. Outdoor demolition and construction require actions to keep dust and moisture out of the facility

(e.g., sealing windows and vents and keeping doors closed or sealed). Containment of dust and

moisture generated from construction inside a facility requires barrier structures (either pre-fabricated or

constructed of more durable materials as needed) and engineering controls to clean the air in and around

the construction or repair site.

c. Infection-Control Risk Assessment

An infection-control risk assessment (ICRA) conducted before initiating repairs, demolition,

construction, or renovation activities can identify potential exposures of susceptible patients to dust and

moisture and determine the need for dust and moisture containment measures. This assessment centers

on the type and extent of the construction or repairs in the work area but may also need to include

adjacent patient-care areas, supply storage, and areas on levels above and below the proposed project.

An example of designing an ICRA as a matrix, the policy for performing an ICRA and implementing its

results, and a sample permit form that streamlines the communication process are available.

281

Knowledge of the air flow patterns and pressure differentials helps minimize or eliminate the

inadvertent dispersion of dust that could contaminate air space, patient-care items, and surfaces.

57, 282, 283

A recent aspergillosis outbreak among oncology patients was attributed to depressurization of the

building housing the HSCT unit while construction was underway in an adjacent building. Pressure

readings in the affected building (including 12 of 25 HSCT-patient rooms) ranged from 0.1 Pa–5.8 Pa.

Unfiltered outdoor air flowed into the building through doors and windows, exposing patients in the

HSCT unit to fungal spores.

283

During long-term projects, providing temporary essential services (e.g.,

toilet facilities) and conveniences (e.g., vending machines) to construction workers within the site will

help to minimize traffic in and out of the area. The type of barrier systems necessary for the scope of

the project must be defined.

12, 120, 250, 279, 284

Depending on the location and extent of the construction, patients may need to be relocated to other

areas in the facility not affected by construction dust.

51, 285

Such relocation might be especially prudent

when construction takes place within units housing immunocompromised patients (e.g., severely

neutropenic patients and patients on corticosteroid therapy). Advance assessment of high-risk locations

and planning for the possible transport of patients to other departments can minimize delays and waiting

time in hallways.

Although hospitals have provided immunocompromised patients with some form of

respiratory protection for use outside their rooms, the issue is complex and remains unresolved until

more research can be done. Previous guidance on this issue has been inconsistent.

Protective

respirators (i.e., N95) were well tolerated by patients when used to prevent further cases of construction-

related aspergillosis in a recent outbreak.

283

The routine use of the N95 respirator by patients, however,

has not been evaluated for preventing exposure to fungal spores during periods of non-construction.

Although health-care workers who would be using the N95 respirator for personal respiratory protect

must be fit-tested, there is no indication that either patients or visitors should undergo fit-testing.

Surveillance activities should augment preventive strategies during construction projects.

3, 4, 20, 110, 286, 287

By determining baseline levels of health-care–acquired airborne and waterborne infections, infection-

control staff can monitor changes in infection rates and patterns during and immediately after

construction, renovations, or repairs.

d. Air Sampling

Air sampling in health-care facilities may be conducted both during periods of construction and on a

periodic basis to determine indoor air quality, efficacy of dust-control measures, or air-handling system

performance via parametric monitoring. Parametric monitoring consists of measuring the physical

performance of the HVAC system in accordance with the system manufacturer’s specifications. A

periodic assessment of the system (e.g., air flow direction and pressure, ACH, and filter efficiency) can

give assurance of proper ventilation, especially for special care areas and operating rooms.

288

Air sampling is used to detect aerosols (i.e., particles or microorganisms). Particulate sampling (i.e.,

total numbers and size range of particulates) is a practical method for evaluating the infection-control

performance of the HVAC system, with an emphasis on filter efficiency in removing respirable particles

(<5 µm in diameter) or larger particles from the air. Particle size is reported in terms of the mass

median aerodynamic diameter (MMAD), whereas count median aerodynamic diameter (CMAD) is

useful with respect to particle concentrations.

Particle counts in a given air space within the health-care facility should be evaluated against counts

obtained in a comparison area. Particle counts indoors are commonly compared with the particulate

levels of the outdoor air. This approach determines the “rank order” air quality

from “dirty” (i.e., the

outdoor air) to “clean” (i.e., air filtered through high-efficiency filters [90%–95% filtration]) to

“cleanest” (i.e., HEPA-filtered air).

288

Comparisons from one indoor area to another may also provide

useful information about the magnitude of an indoor air-quality problem. Making rank-order

comparisons between clean, highly-filtered areas and dirty areas and/or outdoors is one way to interpret

sampling results in the absence of air quality and action level standards.

35, 289

In addition to verifying filter performance, particle counts can help determine if barriers and efforts to

control dust dispersion from construction are effective. This type of monitoring is helpful when

performed at various times and barrier perimeter locations during the project. Gaps or breaks in the

barriers’ joints or seals can then be identified and repaired. The American Conference of Governmental

Industrial Hygienists (ACGIH) has set a threshold limit value-time weighted average (TLV®-TWA) of

10 mg/m

for nuisance dust that contains no asbestos and <1% crystalline silica.

290

Alternatively,

OSHA has set permissible exposure limits (PELs) for inert or nuisance dust as follows: respirable

fraction at 5 mg/m

and total dust at 15 mg/m

291

Although these standards are not measures of a

bioaerosol, they are used for indoor air quality assessment in occupational settings and may be useful

criteria in construction areas. Application of ACGIH guidance to health-care settings has not been

standardized, but particulate counts in health-care facilities are likely to be well below this threshold

value and approaching clean-room standards in certain care areas (e.g., operating rooms).

100

Particle counters and anemometers are used in particulate evaluation. The anemometer measures air

flow velocity, which can be used to determine sample volumes. Particulate sampling usually does not

require microbiology laboratory services for the reporting of results.

Microbiologic sampling of air in health-care facilities remains controversial because of currently

unresolved technical limitations and the need for substantial laboratory support (Box 6). Infection-

control professionals, laboratorians, and engineers should determine if microbiologic and/or particle

sampling is warranted and assess proposed methods for sampling. The most significant technical

limitation of air sampling for airborne fungal agents is the lack of standards linking fungal spore levels

with infection rates. Despite this limitation, several health-care institutions have opted to use

microbiologic sampling when construction projects are anticipated and/or underway in efforts to assess

the safety of the environment for immunocompromised patients.

35, 289

Microbiologic air sampling

should be limited to assays for airborne fungi; of those, the thermotolerant fungi (i.e., those capable of

growing at 95°F–98.6°F [35°C–37°C]) are of particular concern because of their pathogenicity in

immunocompromised hosts.

Use of selective media (e.g., Sabouraud dextrose agar and inhibitory

mold agar) helps with the initial identification of recovered organisms.

Microbiologic sampling for fungal spores performed as part of various airborne disease outbreak

investigations has also been problematic.

18, 49, 106, 111, 112, 289

The precise source of a fungus is often

difficult to trace with certainty, and sampling conducted after exposure may neither reflect the

circumstances that were linked to infection nor distinguish between health-care–acquired and

community-acquired infections. Because fungal strains may fluctuate rapidly in the environment,

health-care–acquired

Aspergillus

spp. infection cannot be confirmed or excluded if the infecting strain is

not found in the health-care setting.

287

Sensitive molecular typing methods (e.g., randomly amplified

polymorphic DNA (RAPD) techniques and a more recent DNA fingerprinting technique that detects

restriction fragment length polymorphisms in fungal genomic DNA) to identify strain differences

among

Aspergillus

spp., however, are becoming increasingly used in epidemiologic investigations of

health-care–acquired fungal infection (A.Streifel, University of Minnesota, 2000).

68, 110, 286, 287, 292–296

During case cluster evaluation, microbiologic

sampling may provide an isolate from the environment

for molecular typing and comparison with patient isolates. Therefore, it may be prudent for the clinical

laboratory to save

Aspergillus

spp. isolated from colonizations and invasive disease cases among

patients in PE, oncology, and transplant services for these purposes.

Box 6. Unresolved issues associated with microbiologic air sampling*

Lack of standards linking fungal spore levels with infection rates (i.e., no safe level of exposure)

Lack of standard protocols for testing (e.g., sampling intervals, number of samples, sampling

locations)
Need

for

substantial laboratory support

Culture issues (e.g., false negatives, insensitivity, lag time between sampling and recording the

results)

New, complex polymerase chain reaction (PCR) analytical methods

Unknown incubation period for Aspergillus spp. infection

Variability of sampler readings

Sensitivity of the sampler used (i.e., the volumes of air sampled)

Lack of details in the literature about describing sampling circumstances (e.g., unoccupied rooms

vs. ongoing activities in rooms, expected fungal concentrations, and rate of outdoor air
penetration)

Lack of correlation between fungal species and strains from the environment and clinical

specimens

Confounding variables with high-risk patients (e.g., visitors and time spent outside of protective

environment [PE] without respiratory protection)

Need for determination of ideal temperature for incubating fungal cultures (95°F [35°C] is the most

commonly used temperature)

* Material in this box is compiled from references 35, 100, 222, 289, and 297.

Sedimentation methods using settle plates and volumetric sampling methods using solid impactors are

commonly employed when sampling air for bacteria and fungi. Settle plates have been used by

numerous investigators to detect airborne bacteria or to measure air quality during medical procedures

(e.g., surgery).

17, 60, 97, 151, 161, 287

Settle plates, because they rely on gravity during sampling, tend to

select for larger particles and lack sensitivity for respirable particles (e.g., individual fungal spores),

especially in highly-filtered environments. Therefore, they are considered impractical for general use.

35,

289, 298–301

Settle plates, however, may detect fungi aerosolized during medical procedures (e.g., during

wound dressing changes), as described in a recent outbreak of aspergillosis among liver transplant

patients.

302

The use of slit or sieve impactor samplers capable of collecting large volumes of air in short periods of

time are needed to detect low numbers of fungal spores in highly filtered areas.

35, 289

In some

outbreaks, aspergillosis cases have occurred when fungal spore concentrations in PE ambient air ranged

as low as 0.9–2.2 colony-forming units per cubic meter (CFU/m

) of air.

18, 94

On the basis of the

expected spore counts in the ambient air and the performance parameters of various types of volumetric

air samplers, investigators of a recent aspergillosis outbreak have suggested that an air volume of at

least 1000 L (1 m

) should be considered when sampling highly filtered areas.

283

Investigators have

also suggested limits of 15 CFU/m

for gross colony counts of fungal organisms and <0.1 CFU/m

for

Aspergillus fumigatus

and other potentially opportunistic fungi in heavily filtered areas (>12 ACH and

filtration of >99.97% efficiency).

120

No correlation of these values with the incidence of health-care–

associated fungal infection rates has been reported.

Air sampling in health-care facilities, whether used to monitor air quality during construction, to verify

filter efficiency, or to commission new space prior to occupancy, requires careful notation of the

circumstances of sampling. Most air sampling is performed under undisturbed conditions. However,

when the air is sampled during or after human activity (e.g., walking and vacuuming), a higher number

of airborne microorganisms likely is detected.

297

The contribution of human activity to the significance

of air sampling and its impact on health-care–associated infection rates remain to be defined.

Comparing microbiologic sampling results from a target area

(e.g., an area of construction) to those

from an unaffected location in the facility can provide information about distribution and concentration

of potential airborne pathogens. A comparison of microbial species densities in outdoor air versus

indoor air has been used to help pinpoint fungal spore bursts. Fungal spore densities in outdoor air are

variable, although the degree of variation with the seasons appears to be more dramatic in the United

States than in Europe.

92, 287, 303

Particulate and microbiologic air sampling have been used when commissioning new HVAC system

installations; however, such sampling is particularly important for newly constructed or renovated PE or

operating rooms. Particulate sampling is used as part of a battery of tests to determine if a new HVAC

system is performing to specifications for filtration and the proper number of ACH.

268, 288, 304

Microbiologic air sampling, however, remains controversial in this application, because no standards for

comparison purposes have been determined. If performed, sampling should be limited to determining

the density of fungal spores per unit volume of air space. High numbers of spores may indicate

contamination of air-handling system components prior to installation or a system deficiency when

culture results are compared with known filter efficiencies and rates of air exchange.

e. External Demolition and Construction

External demolition, planned building implosions, and dirt excavation generate considerable dust and

debris that can contain airborne microorganisms. In one study, peak concentrations in outdoor air at

grade level and HVAC intakes during site excavation averaged 20,000 CFU/m

for all fungi and 500

CFU/m

for

Aspergillus fumigatus

, compared with 19 CFU/m

and 4 CFU/m

, respectively, in the

absence of construction.

280

Many health-care institutions are located in large, urban areas; building

implosions are becoming a more frequent concern. Infection-control risk assessment teams, particularly

those in facilities located in urban renewal areas, would benefit by developing risk management

strategies for external demolition and construction as a standing policy. In light of the events of 11

September 2001, it may be necessary for the team to identify those dust exclusion measures that can be

implemented rapidly in response to emergency situations (Table 8). Issues to be reviewed prior to

demolition include a) proximity of the air intake system to the work site, b) adequacy of window seals

and door seals, c) proximity of areas frequented by immunocompromised patients, and d) location of the

underground utilities (D. Erickson, ASHE, 2000).

120, 250, 273, 276, 277, 280, 305

Table 8. Strategies to reduce dust and moisture intrusion during external demolition and
construction

Item Recommendation

Demolition site

Shroud the site if possible to reduce environmental

contamination.
Dust-generating equipment

Prior to placing dust-generating equipment, evaluate the

                                                                            location to ensure that dust produced by the equipment
                                                                            will not enter the building through open doorways or
                                                                            windows, or through ventilation air intakes.
Construction materials storage

Locate this storage away from the facility and ventilation air

intakes.
Adjacent air intakes

Seal off affected intakes, if possible, or move if funds permit.

HVAC system

Consult with the facility engineer about pressure differentials

and air recirculation options; keep facility air pressure
positive to outside air.
Filters

Ensure that filters are properly installed; change roughing

filters frequently to prevent dust build-up on high-efficiency
filters.
Windows

Seal and caulk to prevent entry of airborne fungal spores.

Doors

Keep closed as much as possible; do not prop open; seal and

                                                                            caulk unused doors (i.e., those that are not designated as
                                                                            emergency exits); use mats with tacky surfaces at outside
                                                                            entrances.
Water utilities

Note location relative to construction area to prevent intrusion

of dust into water systems.*
Medical gas piping

Ensure that these lines/pipes are insulated during periods of

vibration.
Rooftops

Temporarily close off during active demolition/construction

those rooftop areas that are normally open to the public
(e.g., rooftop atrium).
Dust generation

Provide methods (e.g., misting the area with water) to

minimize dust.
Immunocompromised patients

Use walk-ways protected from demolition/construction sites;

avoid outside areas close to these sites; avoid rooftops.
Pedestrian traffic

Close off entry ways as needed to minimize dust intrusion.

Truck traffic

Reroute if possible, or arrange for frequent street cleaning.

Education and awareness+

Encourage reporting of hazardous or unsafe incidents

associated with construction.

* Contamination of water pipes during demolition activities has been associated with health-care–associated transmission of

Legionella

spp.

305

+ When health-care facilities have immunosuppressed patients in their census, telephoning the city building department each month to find

out if buildings are scheduled for demolition is prudent.

Minimizing the entry of outside dust into the HVAC system is crucial in reducing the risk for airborne

contaminants. Facility engineers should be consulted about the potential impact of shutting down the

system or increasing the filtration. Selected air handlers, especially those located close to excavation

sites, may have to be shut off temporarily to keep from overloading the system with dust and debris.

Care is needed to avoid significant facility-wide reductions in pressure differentials that may cause the

building to become negatively pressured relative to the outside. To prevent excessive particulate

overload and subsequent reductions in effectiveness of intake air systems that cannot be shut off

temporarily, air filters must be inspected frequently for proper installation and function. Excessive dust

penetration can be avoided if recirculated air is maximally utilized while outdoor air intakes are shut

down. Scheduling demolition and excavation during the winter, when

Aspergillus

spp. spores may be

present in lower numbers, can help, although seasonal variations in spore density differ around the

world.

92, 287, 303

Dust control can be managed by misting the dirt and debris during heavy dust-

generating activities. To decrease the amount of aerosols from excavation

and demolition projects,

nearby windows, especially in areas housing immunocompromised patients, can be sealed and window

and door frames caulked or weather-stripped to prevent dust intrusion.

50, 301, 306

Monitoring for

adherence to these control measures throughout

demolition or excavation is crucial. Diverting

pedestrian traffic away from the construction sites decreases the amount of dust

tracked back into

the

health-care facility and minimizes exposure of high-risk patients to environmental pathogens.

Additionally, closing entrances near construction or demolition sites might be beneficial; if this is not

practical, creating an air lock (i.e., pressurizing the entry way) is another option.

f. Internal Demolition, Construction, Renovations, and Repairs

The focus of a properly implemented infection-control program during interior construction and repairs

is containment of dust and moisture. This objective is achieved by a) educating construction workers

about the importance of control measures; b) preparing the site; c) notifying and issuing advisories for

staff, patients, and visitors; d) moving staff and patients and relocating patients as needed; e) issuing

standards of practice and precautions during activities and maintenance; f) monitoring for adherence to

control measures during construction and providing prompt feedback about lapses in control; g)

monitoring HVAC performance; h) implementing daily clean-up, terminal cleaning and removal of

debris upon completion; and i) ensuring the integrity of the water system during and after construction.

These activities should be coordinated with engineering staff and infection-control professionals.

Physical barriers capable of containing smoke and dust will confine dispersed fungal spores to the

construction zone.

279, 284, 307, 308

The specific type of physical barrier required depends on the project’s

scope and duration and on local fire codes. Short-term projects that result in minimal dust dispersion

(e.g., installation of new cables or wiring above ceiling tiles) require only portable plastic enclosures

with negative pressure and HEPA filtration of the exhaust air from the enclosed work area. The

placement of a portable industrial-grade HEPA filter device capable of filtration rate of 300–800 ft

/min.

adjacent to the work area will help to remove fungal spores, but its efficacy is dependent on the supplied

ACH and size of the area. If the project is extensive but short-term, dust-abatement, fire-resistant

plastic curtains (e.g., Visqueen®) may be adequate. These should be completely airtight and sealed

from ceiling to floor with overlapping curtains;

276, 277, 309

holes, tears, or other perforations should be

repaired promptly with tape. A portable, industrial-grade HEPA filter unit on continuous operation is

needed within the contained area, with the filtered air exhausted to the outside of the work zone.

Patients should not remain in the room when dust-generating activities are performed. Tools to assist

the decision-making process regarding selection of barriers based on an ICRA approach are available.

281

More elaborate barriers are indicated for long-term projects that generate moderate to large amounts of

dust. These barrier structures typically consist of rigid, noncombustible walls constructed from sheet

rock, drywall, plywood, or plaster board and covered with sheet plastic (e.g., Visqueen®). Barrier

requirements to prevent the intrusion of dust into patient-care areas include a) installing a plastic dust

abatement curtain before construction of the rigid barrier; b) sealing and taping all joint edges including

the top and bottom; c) extending the barrier from floor to floor, which takes into account the space

[approximately 2–8 ft.] above the finished, lay-down ceiling; and d) fitting or sealing any temporary

doors connecting the construction zone to the adjacent area. (See Box 7 for a list of the various

construction and repair activities that require the use of some type of barrier.)

Box 7. Construction/repair projects that require barrier structures*

Demolition of walls, wallboard, plaster, ceramic tiles, ceiling tiles, and ceilings

Removal of flooring and carpeting, windows and doors, and casework

Working with sinks and plumbing that could result in aerosolization of water in high-risk areas

Exposure of ceiling spaces for demolition and for installation or rerouting of utility services (e.g.,

rewiring, electrical conduction installation, HVAC ductwork, and piping)

Crawling into ceiling spaces for inspection in a manner that may dislodge dust

Demolition, repair, or construction of elevator shafts

Repairing water damage

* Material for this box was compiled from references 120, 250, 273, 276, and 277.

Dust and moisture abatement and control rely primarily on the impermeable barrier containment

approach; as construction continues, numerous opportunities can lead to dispersion of dust to other areas

of the health-care facility. Infection-control measures that augment the use of barrier containment

should be undertaken (Table 9).

Dust-control measures for clinical laboratories are an essential part of the infection-control strategy

during hospital construction or renovation. Use of plastic or solid barriers may be needed if the ICRA

determines that air flow from construction areas may introduce airborne contaminants into the

laboratory space. In one facility, pseudofungemia clusters attributed to

Aspergillus

spp. and

Penicillium

spp. were linked to improper air flow patterns and construction projects adjacent to the laboratory;

intrusion of dust and spores into a biological safety cabinet from construction activity immediately next

to the cabinet resulted in a cluster of cultures contaminated with

Aspergillus niger

310, 311

Reportedly,

no barrier containment was used and the HEPA filtration system was overloaded with dust. In addition,

an outbreak of pseudobacteremia caused by

Bacillus

spp. occurred in another hospital during

construction above a storage area for blood culture bottles.

207

Airborne spread of

Bacillus

spp. spores

resulted in contamination of the bottles’ plastic lids, which were not disinfected or handled with proper

aseptic technique prior to collection of blood samples.

Table 9. Infection-control measures for internal construction and repair projects*+

Infection-control measure

Steps for implementation

Prepare for the project.

1. Use a multi-disciplinary team approach to incorporate infection control into the

project.

2. Conduct the risk assessment and a preliminary walk-through with project

managers and staff.

Educate staff and construction workers.

1. Educate staff and construction workers about the importance of adhering to

infection-control measures during the project.

2. Provide educational materials in the language of the workers.

3. Include language in the construction contract requiring construction workers and

subcontractors to participate in infection-control training.

Issue hazard and warning notices.

1. Post signs to identify construction areas and potential hazards.

2. Mark detours requiring pedestrians to avoid the work area.

Relocate high-risk patients as needed,

especially if the construction is in or

adjacent to a PE area.

1. Identify target patient populations for relocation based on the risk assessment.

2. Arrange for the transfer in advance to avoid delays.

3. At-risk patients should wear protective respiratory equipment (e.g., a high-

efficiency mask) when outside their PE rooms.

Establish alternative traffic patterns for

staff, patients, visitors, and construction

workers.

1. Determine appropriate alternate routes from the risk assessment.

2. Designate areas (e.g., hallways, elevators, and entrances/exits) for construction-

worker use.

3. Do not transport patients on the same elevator with construction materials and

debris.

Infection-control measure

Steps for implementation

Erect appropriate barrier containment.

1. Use prefabricated plastic units or plastic sheeting for short-term projects that

will generate minimal dust.

2. Use durable rigid barriers for ongoing, long-term projects.

Establish proper ventilation.

1. Shut off return air vents in the construction zone, if possible, and seal around

grilles.

2. Exhaust air and dust to the outside, if possible.

3. If recirculated air from the construction zone is unavoidable, use a pre-filter and

a HEPA filter before the air returns to the HVAC system.

4. When vibration-related work is being done that may dislodge dust in the

ventilation system or when modifications are made to ductwork serving

occupied spaces, install filters on the supply air grilles temporarily.

5. Set pressure differentials so that the contained work area is under negative

pressure.

6. Use air flow monitoring devices to verify the direction of the air pattern.

7. Exhaust air and dust to the outside, if possible.

8. Monitor temperature, air changes per hour (ACH), and humidity levels

(humidity levels should be <65%).

9. Use portable, industrial grade HEPA filters in the adjacent area and/or the

construction zone for additional ACH.

10. Keep windows closed, if possible.

Control solid debris.

1. When replacing filters, place the old filter in a bag prior to transport and dispose

as a routine solid waste.

2. Clean the construction zone daily or more often as needed.

3. Designate a removal route for small quantities of solid debris.

4. Mist debris and cover disposal carts before transport (i.e., leaving the

construction zone).

5. Designate an elevator for construction crew use.

6. Use window chutes and negative pressure equipment for removal of larger

pieces of debris while maintaining pressure differentials in the construction

zone.

7. Schedule debris removal to periods when patient exposures to dust is minimal.

Control water damage.

1. Make provisions for dry storage of building materials.

2. Do not install wet, porous building materials (i.e., sheet rock).

3. Replace water-damaged porous building materials if they cannot be completely

dried out within 72 hours.

Control dust in air and on surfaces.

1. Monitor the construction area daily for compliance with the infection-control

plan.

2. Protective outer clothing for construction workers should be removed before

entering clean areas.

3. Use mats with tacky surfaces within the construction zone at the entry; cover

sufficient area so that both feet make contact with the mat while walking

through the entry.

4. Construct an anteroom as needed where coveralls can be donned and removed.

5. Clean the construction zone and all areas used by construction workers with a

wet mop.

6. If the area is carpeted, vacuum daily with a HEPA-filtered–equipped vacuum.

7. Provide temporary essential services (e.g., toilets) and worker conveniences

(e.g, vending machines) in the construction zone as appropriate.

8. Damp-wipe tools if removed from the construction zone or left in the area.

9. Ensure that construction barriers remain well sealed; use particle sampling as

needed.

10. Ensure that the clinical laboratory is free from dust contamination.

Infection-control measure

Steps for implementation

Complete the project.

1. Flush the main water system to clear dust-contaminated lines.

2. Terminally clean the construction zone before the construction barriers are

removed.

3. Check for visible mold and mildew and eliminate (i.e., decontaminate and

remove), if present.

4. Verify appropriate ventilation parameters for the new area as needed.

5. Do not accept ventilation deficiencies, especially in special care areas.

6. Clean or replace HVAC filters using proper dust-containment procedures.

7. Remove the barriers and clean the area of any dust generated during this work.

8. Ensure that the designated air balances in the operating rooms (OR) and

protective environments (PE) are achieved before occupancy.

9. Commission the space as indicated, especially in the OR and PE, ensuring that

the room’s required engineering specifications are met.

* Material in this table includes information from D. Erickson, ASHE, 2000.

+ Material in this table was compiled from references 19, 51, 67, 80, 106, 120, 250, 266, 273, 276–278, 280, 285, and 309, 312–315.

5. Environmental Infection-Control Measures for Special Health-Care
Settings

Areas in health-care facilities that require special ventilation include a) operating rooms; b) PE rooms

used by high-risk, immunocompromised patients; and c) AII rooms for isolation of patients with

airborne infections (e.g., those caused by

M. tuberculosis

, VZV, or measles virus). The number of

rooms required for PE and AII are determined by a risk assessment of the health-care facility.

Continuous, visual monitoring of air flow direction is required for new or renovated pressurized

rooms.

120, 256

a. Protective Environments (PE)

Although the exact configuration and specifications of PEs might differ among hospitals, these care

areas for high-risk, immunocompromised patients are designed to minimize fungal spore counts in air

by maintaining a) filtration of incoming air by using central or point-of-use HEPA filters; b) directed

room air flow [i.e., from supply on one side of the room, across the patient, and out through the exhaust

on the opposite side of the room]; c) positive room air pressure of 2.5 Pa [0.01" water gauge] relative to

the corridor; d) well-sealed rooms; and e) >12 ACH.

44, 120, 251, 254, 316–319

Air flow rates must be adjusted

accordingly to ensure sufficient ACH, and these rates vary depending on certain factors (e.g., room air

leakage area). For example, to provide >12 ACH in a typical patient room with 0.5 sq. ft. air leakage,

the air flow rate will be minimally 125 cubic feet/min (cfm).

320, 321

Higher air flow rates may be

needed. A general ventilation diagram for a positive-pressure room is given in Figure 2. Directed room

air flow in PE rooms is not laminar; parallel air streams are not generated. Studies attempting to

demonstrate patient benefit from laminar air flow in a PE setting are equivocal.

316, 318, 319, 322 - 327

Air flow direction at the entrances to these areas should be maintained and verified, preferably on a

daily basis, using either a visual means of indication (e.g., smoke tubes and flutter strips) or

manometers. Permanent installation of a visual monitoring device is indicated for new PE construction

and renovation.

120

Facility service structures can interfere with the proper unidirectional air flow from

the patients’ rooms to the adjacent corridor. In one outbreak investigation,

Aspergillus

spp. infections in

critical care unit may have been associated with a pneumatic specimen transport system, a textile

disposal duct system, and central vacuum lines for housekeeping, all of which disrupted proper air flow

from the patients’ rooms to the outside and allowed entry of fungal spores into the unit (M.McNeil,

CDC, 2000).

Figure 2. Example of positive-pressure room control for protection from airborne
environmental microbes (PE)* + §

* Stacked black boxes represent patient’s bed. Long open box with cross-hatch represents supply air. Open boxes with single,

diagonal slashes represent air exhaust registers. Arrows indicate directions of air flow.

+ Possible uses include immunocompromised patient rooms (e.g., hematopoietic stem cell transplant or solid organ transplant

procedure rooms) and orthopedic operating rooms.

§ Positive-pressure room engineering features include

positive pressure (greater supply than exhaust air volume);

pressure differential range of 2.5–8 Pa (0.01–0.03-in. water gauge), ideal at 8 Pa;

air flow volume differential >125-cfm supply versus exhaust;

sealed room, approximately 0.5-sq. ft. leakage;

clean to dirty air flow;

monitoring;

>12 air changes per hour (ACH); and

return air if refiltered.

¶ This diagram is a generic illustration of air flow in a typical installation. Alternative air flow arrangements are recognized.

Adapted and used with permission from A. Streifel and the publisher of reference 328 (Penton Media, Inc.)

The use of surface fungicide treatments is becoming more common, especially for building materials.

329

Copper-based compounds have demonstrated anti-fungal activity and are often applied to wood or paint.

Copper-8-quinolinolate was used on environmental surfaces contaminated with

Aspergillus

spp. to

control one reported outbreak of aspergillosis.

310

The compound was also incorporated into the

fireproofing material of a newly constructed hospital to help decrease the environmental spore

burden.

316

b. Airborne Infection Isolation (AII)

Acute-care inpatient facilities need at least one room equipped to house patients with airborne infectious

disease. Every health-care facility, including ambulatory and long-term care facilities, should undertake

an ICRA to identify the need for AII areas. Once the need is established, the appropriate ventilation

equipment can be identified. Air handling systems for this purpose need not be restricted to central

systems. Guidelines for the prevention of health-care–acquired TB have been published in response to

multiple reports of health-care–associated transmission of multi-drug resistant strains.

4, 330

In reports

documenting health-care–acquired TB, investigators have noted a failure to comply fully with

prevention measures in established guidelines.

331 - 345

These gaps highlight the importance of prompt

recognition of the disease, isolation of patients, proper treatment, and engineering controls. AII rooms

Monitor

Corridor

Bathroom

are also appropriate for the care and management of smallpox patients.

Environmental infection

control with respect to smallpox is currently being revisited (see Appendix E).

Salient features of engineering controls for AII areas include a) use of negative pressure rooms with

close monitoring of air flow direction using manometers or temporary or installed visual indicators [e.g.,

smoke tubes and flutter strips] placed in the room with the door closed; b) minimum 6 ACH for existing

facilities, >12 ACH for areas under renovation or for new construction; and c) air from negative

pressure rooms and treatment rooms exhausted directly to the outside if possible.

4, 120, 248

As with PE,

airflow rates need to be determined to ensure the proper numbers of ACH.

320, 321

AII rooms can be

constructed either with (Figure 3) or without (Figure 4) an anteroom. When the recirculation of air from

AII rooms is unavoidable, HEPA filters should be installed in the exhaust duct leading from the room to

the general ventilation system. In addition to UVGI fixtures in the room, UVGI can be placed in the

ducts as an adjunct measure to HEPA filtration, but it can not replace the HEPA filter.

4, 346

A UVGI

fixture placed in the upper room, coupled with a minimum of 6 ACH, also provides adequate air

cleaning.

248

Figure 3. Example of negative-pressure room control for airborne infection isolation
(AII)* + §¶

* Stacked black boxes represent patient’s bed. Long open box with cross-hatch represents supply air. Open boxes with single,

diagonal slashes represent air exhaust registers. Arrows indicate direction of air flow.

+ Possible uses include treatment or procedure rooms, bronchoscopy rooms, and autopsy.

§ Negative-pressure room engineering features include

negative pressure (greater exhaust than supply air volume);

pressure differential of 2.5 Pa (0.01-in. water gauge);

air flow volume differential >125-cfm exhaust versus supply;

sealed room, approximately 0.5-sq. ft. leakage;

clean to dirty air flow;

monitoring;

>12 air changes per hour (ACH) new or renovation, 6 ACH existing; and

exhaust to outside or HEPA-filtered if recirculated.

¶ This diagram is a generic illustration of air flow in a typical installation. Alternative air flow arrangements are recognized.

Adapted and used with permission from A. Streifel and the publisher of reference 328 (Penton Media, Inc.)

One of the components of airborne infection isolation is respiratory protection for health-care workers

and visitors when entering AII rooms.

4, 6, 347

Recommendations of the type of respiratory protection are

dependent on the patient’s airborne infection (indicating the need for AII) and the risk of infection to

Monitor

Corridor

Bathroom

persons entering the AII room. A more in-depth discussion of respiratory protection in this instance is

presented in the current isolation guideline;

a revision of this guideline is in development. Cough-

inducing procedures (e.g., endotracheal intubation and suctioning of known or suspected TB patients,

diagnostic sputum induction, aerosol treatments, and bronchoscopy) require similar precautions.

348–350

Additional engineering measures are necessary for the management of patients requiring PE (i.e.,

allogeneic HSCT patients) who concurrently have airborne infection. For this type of patient treatment,

an anteroom (Figure 4) is required in new construction and renovation as per AIA guidelines.

120

Figure 4. Example of airborne infection isolation (AII) room with anteroom and neutral
anteroom* + §

* The top diagram indicates air flow patterns when patient with only airborne infectious disease occupies room. Middle and

bottom diagrams indicate recommended air flow patterns when room is occupied by immunocompromised patient with

airborne infectious disease. Stacked black boxes represent patient beds. Long open boxes with cross-hatches represent

supply air. Open boxes with single, diagonal slashes represent air exhaust registers. Arrows indicate directions of air flow.

+ AII isolation room with anteroom engineering features include

pressure differential of 2.5 Pa (0.01-in. water gauge) measured at the door between patient room and anteroom;

air flow volume differential >125-cfm. depending on anteroom air flow direction (pressurized versus depressurized);

Anteroom

Corridor

Monitor

Bathroom

AII only

Anteroom

Corridor

Monitor

Bathroom

Neutral Anteroom

Monitor

Corridor

Bathroom

AII and immuno-
compromised

sealed room with approximately 0.5-sq. ft. leakage;

clean to dirty air flow

monitoring;

>12 air changes per hour (ACH) new or renovation, 6 ACH existing; and

anteroom air flow patterns. The small

in panels 1 and 2 indicate the anteroom is pressurized (supply versus exhaust),

while the small

in panel 3 indicates the anteroom is depressurized (exhaust versus supply).

§ Used with permission of A. Streifel, University of Minnesota

The pressure differential of an anteroom can be positive or negative relative to the patient in the room.

120

An anteroom can act as an airlock (Figure 4). If the anteroom is positive relative to the air space in the

patient’s room, staff members do not have to mask prior to entry into the anteroom if air is directly

exhausted to the outside and a minimum of 10 ACH (Figure 4, top diagram).

120

When an anteroom is

negative relative to both the AII room and the corridor, health-care workers must mask prior to entering

the anteroom (Figure 4, bottom diagram). If an AII

room with an anteroom is not available, use of a

portable, industrial-grade HEPA filter unit may help to increase the number of ACHs while facilitating

the removal of fungal spores; however, a fresh air source must be present

to achieve the proper air

exchange rate. Incoming ambient air should receive HEPA filtration.

c. Operating Rooms

Operating room air may contain microorganisms, dust, aerosol, lint, skin squamous epithelial cells, and

respiratory droplets. The microbial level in operating room air is directly proportional to the number of

people moving in the room.

351

One study documented lower infection rates with coagulase-negative

staphylococci among patients when operating room traffic during the surgical procedure was limited.

352

Therefore, efforts should be made to minimize personnel traffic during operations. Outbreaks of SSIs

caused by group A beta-hemolytic streptococci have been traced to airborne transmission from

colonized operating-room personnel to patients.

150–154

Several potential health-care–associated

pathogens (e.g.,

Staphylococcus aureus

and

Staphylococcus epidermidis

) and drug-resistant organisms

have also been recovered from areas adjacent to the surgical field,

353

but the extent to which the

presence of bacteria near the surgical field influences the development of postoperative SSIs is not

clear.

354

Proper ventilation, humidity (<68%), and temperature control in the operating room is important for the

comfort of surgical personnel and patients, but also in preventing environmental conditions that

encourage growth and transmission of microorganisms.

355

Operating rooms should be maintained at

positive pressure with respect to corridors and adjacent areas.

356

Operating rooms typically do not have

a variable air handling system. Variable air handling systems are permitted for use in operating rooms

only if they continue to provide a positive pressure with respect to the corridors and adjacent areas and

the proper ACHs are maintained when the room is occupied. Conventional operating-room ventilation

systems produce a minimum of about 15 ACH of filtered air for thermal control, three (20%) of which

must be fresh air.

120, 357, 358

Air should be introduced at the ceiling and exhausted near the floor.

357, 359

Laminar airflow and UVGI have been suggested as adjunct measures to reduce SSI risk for certain

operations. Laminar airflow is designed to move particle-free air over the aseptic operating field at a

uniform velocity (0.3–0.5 m/sec), sweeping away particles in its path. This air flow can be directed

vertically or horizontally, and recirculated air is passed through a HEPA filter.

360–363

Neither laminar

airflow nor UV light, however, has been conclusively shown to decrease overall SSI risk.

356, 364–370

Elective surgery on infectious TB patients should be postponed until such patients have received

adequate drug therapy. The use of general anesthesia in TB patients poses infection-control challenges

because intubation can induce coughing, and the anesthesia breathing circuit apparatus potentially can

become contaminated.

371

Although operating room suites at 15 ACH exceed the air exchanges required

for TB isolation, the positive air flow relative to the corridor could result in health-care–associated

transmission of TB to operating-room personnel. If feasible, intubation and extubation of the TB

surgical patient should be performed in AII. AIA currently does not recommend changing pressure

from positive to negative or setting it to neutral; most facilities lack the capability to do so.

120

When

emergency surgery is indicated for a suspected/diagnosed infectious TB patient, taking specific

infection-control measures is prudent (Box 8).

Box 8. Strategy for managing TB patients and preventing airborne transmission in
operating rooms*

1.  If emergency surgery is indicated for a patient with active TB, schedule the TB patient as the last
    surgical case to provide maximum time for adequate ACH.
2.  Operating room personnel should use NIOSH-approved N95 respirators without exhalation valves.

347

3. Keep the operating room door closed after the patient is intubated, and allow adequate time for
sufficient ACH to remove 99% of airborne particles (Appendix B, Table B.1.):

a) after the patient is intubated and particularly if intubation produces coughing;

b) if the door to the operating suite must be opened, and intubation induces coughing in the

patient; or

c) after the patient is extubated and suctioned [unless a closed suctioning system is present].

4.  Extubate the patient in the operating room or allow the patient to recover in AII rather than in the
    regular open recovery facilities.
5.  Temporary use of a portable, industrial grade HEPA filter may expedite removal of airborne
    contaminants (fresh-air exchange requirements for proper ventilation must still be met).+
6. Breathing circuit filters with 0.1–0.2 µm pore size can be used as an adjunct infection-control
    measure.

373, 374

* Material in this table was compiled from references 4, 347, and 372–374.

+ The placement of portable HEPA filter units in the operating room must be carefully evaluated for potential disruptions in normal air flow.

The portable unit should be turned off while the surgical procedure is underway and turned on following extubation. Portable HEPA filter

units previously placed in construction areas may be used in subsequent patient care, provided that all internal and external surfaces are

cleaned and the filter’s performance is verified with appropriate particle testing and is changed, if needed.

Table 10. Summary of ventilation specifications in selected areas of health-care facilities*

Specifications

AII room+

PE room

Critical care

room§

Isolation

anteroom

Operating

room

Air pressure¶

Negative

Positive

Positive, negative,

or neutral

Positive or

negative

Positive

Room air changes

>6 ACH (for

existing rooms);

>12 ACH (for

renovation or new

construction)

>12 ACH

>6 ACH

>10 ACH

>15 ACH

Sealed**

Yes Yes No Yes Yes

Filtration supply

90% (dust-spot

ASHRAE 52.1

1992)

99.97%++ >90% >90% 90%

Recirculation

No§§ Yes Yes No Yes

* Material in this table is compiled from references 35 and 120.

+ Includes bronchoscopy suites.

§ Positive pressure and HEPA filters may be preferred in some rooms in intensive care units (ICUs) caring for large numbers of

immunocompromised patients.

¶ Clean-to-dirty: negative to an infectious patient, positive away from an immunocompromised patient.

** Minimized infiltration for ventilation control; pertains to windows, closed doors, and surface joints.

++ Fungal spore filter at point of use (HEPA at 99.97% of 0.3 µm particles).

§§ Recirculated air may be used if the exhaust air is first processed through a HEPA filter.

¶¶ Table used with permission of the publisher of reference 35 (Lippincott Williams and Wilkins).

6. Other Aerosol Hazards in Health-Care Facilities

In addition to infectious bioaerosols, several crucial non-infectious, indoor air-quality issues must be

addressed by health-care facilities. The presence of sensitizing and allergenic agents and irritants in the

workplace (e.g., ethylene oxide, glutaraldehyde, formaldehyde, hexachlorophene, and latex allergens

375

)

is increasing. Asthma and dermatologic and systemic reactions often result with exposure to these

chemicals. Anesthetic gases and aerosolized medications (e.g., ribavirin, pentamidine, and

aminoglycosides) represent some of the emerging potentially hazardous exposures to health-care

workers. Containment of the aerosol at the source is the first level of

engineering control, but personal

protective equipment (e.g., masks, respirators, and glove liners) that distances the worker from the

hazard also may be needed.

Laser plumes and surgical smoke represent another potential risk for health-care workers.

376–378

Lasers

transfer electromagnetic energy into tissues, resulting in the release of a heated plume that includes

particles, gases, tissue debris, and offensive smells. One concern is that aerosolized infectious material

in the laser plume might reach the nasal mucosa of surgeons and adjacent personnel. Although some

viruses (i.e., varicella-zoster virus, pseudorabies virus, and herpes simplex virus) do not aerosolize

efficiently,

379, 380

other viruses and bacteria (e.g., human papilloma virus [HPV], HIV, coagulase-

negative

Staphylococcus, Corynebacterium

spp.,

and Neisseria

spp.) have been detected in laser

plumes.

381–387

The presence of an infectious agent in a laser plume may not, however, be sufficient to

cause disease from airborne exposure, especially if the normal mode of transmission for the agent is not

airborne. No evidence indicated that HIV or hepatitis B virus (HBV) has been transmitted via

aerosolization and inhalation.

388

Although continuing studies are needed to fully evaluate the risk of laser plumes to surgical personnel,

the prevention measures in these other guidelines should be followed: a) NIOSH recommendations,

378

b) the

Recommended Practices for Laser Safety in Practice Settings

developed by the Association of

periOperative Registered Nurses [AORN],

389

c) the assessments of ECRI,

390–392

and d) the ANSI

standard.

393

These guidelines recommend the use of a) respirators (N95 or N100) or full face shields

and masks,

260

b) central wall-suction units with in-line filters to collect particulate matter from minimal

plumes, and c) dedicated mechanical smoke exhaust systems with a high-efficiency filter to remove

large amounts of laser plume. Although transmission of TB has occurred as a result of abscess

management practices that lacked airborne particulate control measures and respiratory protection, use

of a smoke evacuator or needle aspirator and a high degree of clinical awareness can help protect health-

care workers when excising and draining an extrapulmonary TB abscess.

137

D. Water

1. Modes of Transmission of Waterborne Diseases

Moist environments and aqueous solutions in health-care settings have the potential to serve as

reservoirs for waterborne microorganisms. Under favorable environmental circumstances (e.g., warm

temperature and the presence of a source of nutrition), many bacterial and some protozoal

microorganisms can either proliferate in active growth or remain for long periods in highly stable,

environmentally resistant (yet infectious) forms. Modes of transmission for waterborne infections

include a) direct contact [e.g., that required for hydrotherapy]; b) ingestion of water [e.g., through

consuming contaminated ice]; c) indirect-contact transmission [e.g., from an improperly reprocessed

medical device];

d) inhalation of aerosols dispersed from water sources;

and e) aspiration of

contaminated water. The first three modes of transmission are commonly associated with infections

caused by gram-negative bacteria and nontuberculous mycobacteria (NTM). Aerosols generated from

water sources contaminated with

Legionella

spp. often serve as the vehicle for introducing legionellae to

the respiratory tract.

394

2. Waterborne Infectious Diseases in Health-Care Facilities

a. Legionellosis

Legionellosis is a collective term describing infection produced by

Legionella

spp., whereas

Legionnaires disease is a multi-system illness with pneumonia.

395

The clinical and epidemiologic

aspects of these diseases (Table 11) are discussed extensively in another guideline.

Although

Legionnaires disease is a respiratory infection, infection-control measures intended to prevent health-

care–associated cases center on the quality of water—the principal reservoir for

Legionella

spp.

Table 11. Clinical and epidemiologic characteristics of legionellosis/Legionnaires disease

References

Causative agent

Legionella pneumophila

(90% of infections);

L. micdadei, L.

bozemanii, L. dumoffii, L. longbeachii,

(14 additional species

can cause infection in humans)

395–399

Mode of transmission

Aspiration of water, direct inhalation or water aerosols

3, 394–398, 400

Source of exposure

Exposure to environmental sources of

Legionella

spp. (i.e.,

water or water aerosols)

31, 33, 401–414

Clinical syndromes and

diseases

Two distinct illnesses: a) Pontiac fever [a milder, influenza-

like illness]; and b) progressive

pneumonia

that may be

accompanied by cardiac, renal, and gastrointestinal

involvement

3, 397–399, 415–422

Populations at greatest

risk

Immunosuppressed patients (e.g., transplant patients, cancer

patients, and patients receiving corticosteroid therapy);

immunocompromised patients (e.g., surgical patients,

patients with underlying chronic lung disease, and dialysis

patients); elderly persons; and patients who smoke

395–397, 423–433

Occurrence

Proportion of community-acquired pneumonia caused by

Legionella

spp. ranges from 1%–5%; estimated annual

incidence among the general population is 8,000–18,000

cases in the United States; the incidence of health-care–

associated pneumonia (0%–14%) may be underestimated if

appropriate laboratory diagnostic methods are unavailable.

396, 397, 434–444

Mortality rate

Mortality declined markedly during 1980–1998, from 34% to

12% for all cases; the mortality rate is higher among persons

with health-care–associated pneumonia compared with the

rate among community-acquired pneumonia patients (14%

for health-care–associated pneumonia versus 10% for

community-acquired pneumonia [1998 data]).

395–397, 445

Legionella

spp. are commonly found in various natural and man-made aquatic environments

446, 447

and

can enter health-care facility water systems in low or undetectable numbers.

448, 449

Cooling towers,

evaporative condensers, heated potable water distribution systems, and locally-produced distilled water

can provide environments for multiplication of legionellae.

450–454

In several hospital outbreaks, patients

have been infected through exposure to contaminated aerosols generated by cooling towers, showers,

faucets, respiratory therapy equipment, and room-air humidifiers.

401–410, 455

Factors that enhance

colonization and amplification of legionellae

in man-made water environments include a) temperatures

of 77°F–107.6°F [25°C–42°C],

456–460

b) stagnation,

461

c) scale and sediment,

462

and d) presence of

certain free-living aquatic amoebae that can support intracellular growth of legionellae.

462, 463

The

bacteria multiply within single-cell protozoa in the environment and within alveolar macrophages in

humans.

b. Other Gram-Negative Bacterial Infections

Other gram-negative bacteria present in potable water also can cause health-care–associated infections.

Clinically important, opportunistic organisms in tap water include

Pseudomonas aeruginosa,

Pseudomonas

spp.,

Burkholderia cepacia, Ralstonia pickettii, Stenotrophomonas maltophilia

, and

Sphingomonas

spp. (Tables 12 and 13). Immunocompromised patients are at greatest risk of developing

infection. Medical conditions associated with these bacterial agents range from colonization of the

respiratory and urinary tracts to deep, disseminated infections that can result in pneumonia and

bloodstream bacteremia. Colonization by any of these organisms often precedes the development of

infection. The use of tap water in medical care (e.g., in direct patient care, as a diluent for solutions, as

a water source for medical instruments and equipment, and during the final stages of instrument

disinfection) therefore presents a potential risk for exposure. Colonized

patients also can serve as a

source of contamination, particularly for moist environments of medical equipment (e.g., ventilators).

In addition to

Legionella

spp.,

Pseudomonas aeruginosa

and

Pseudomonas

spp. are among the most

clinically relevant, gram-negative, health-care–associated pathogens identified from water. These and

other gram-negative, non-fermentative bacteria have minimal nutritional requirements (i.e., these

organisms can grow in distilled water) and can tolerate a variety of physical conditions. These attributes

are critical to the success of these organisms as health-care–associated pathogens. Measures to prevent

the spread of these organisms and other waterborne, gram-negative bacteria include hand hygiene, glove

use, barrier precautions, and eliminating potentially contaminated environmental reservoirs.

464, 465

Table 12. Pseudomonas aeruginosa infections in health-care facilities

References

Clinical syndromes and

diseases

Septicemia, pneumonia (particularly ventilator-associated),

chronic respiratory infections among cystic fibrosis patients,

urinary tract infections, skin and soft-tissue infections (e.g., tissue

necrosis and hemorrhage), burn-wound infections, folliculitis,

endocarditis, central nervous system infections (e.g., meningitis

and abscess), eye infections, and bone and joint infections

466–503

Modes of transmission

Direct contact with water, aerosols; aspiration of water and

inhalation of water aerosols; and indirect transfer from moist

environmental surfaces via hands of health-care workers

28, 502–506

Environmental sources of

pseudomonads in health-

care settings

Potable (tap) water, distilled water, antiseptic solutions

contaminated with tap water, sinks, hydrotherapy pools,

whirlpools and whirlpool spas, water baths, lithotripsy therapy

tanks, dialysis water, eyewash stations, flower vases, and

endoscopes with residual moisture in the channels

28, 29, 466, 468,

507–520

Environmental sources of

pseudomonads in the

community

Fomites (e.g., drug injection equipment stored in contaminated

water)

494, 495

Populations at greatest risk

Intensive care unit (ICU) patients (including neonatal ICU),

transplant patients (organ and hematopoietic stem cell),

neutropenic patients, burn therapy and hydrotherapy patients,

patients with malignancies, cystic fibrosis patients, patients with

underlying medical conditions, and dialysis patients

28, 466, 467, 472,

477, 493, 506–508,

511, 512, 521–526

Table 13. Other gram-negative bacteria associated with water and moist environments

Implicated contaminated environmental vehicle

References

Burkholderia cepacia

Distilled water

527

Contaminated

solutions

and disinfectants

528, 529

Dialysis

machines

527

Nebulizers

530–532

Water

baths

533

Intrinsically-contaminated mouthwash*

534

Ventilator

temperature

probes

535

Stenotrophomonas maltophlia, Sphingomonas spp.

Distilled water

536, 537

Contaminated solutions and disinfectants

529

Dialysis

machines

527

Nebulizers

530–532

Water

538

Ventilator

temperature

probes

539

Ralstonia pickettii

Fentanyl

solutions

540

Chlorhexidine

541

Distilled

water

541

Contaminated respiratory therapy solution

541, 542

Serratia marcescens

Potable

water

543

Contaminated

antiseptics (i.e., benzalkonium chloride

544–546

and chlorhexidine)

Contaminated

disinfectants (i.e., quaternary ammonium

547, 548

compounds and glutaraldehyde)

Acinetobacter spp.

Medical

equipment

that collects moisture (e.g., mechanical

549–556

ventilators, cool mist humidifiers, vaporizers, and mist

tents)

Room humidifiers

553, 555

Environmental

surfaces

557–564

Enterobacter spp.

Humidifier

water

565

Intravenous

fluids

566–578

Unsterilized

cotton

swabs

573

Ventilators

565,

569

Rubber piping on a suctioning machine

565, 569

Blood

gas

analyzers

570

* This report describes intrinsic contamination (i.e., occurring during manufacture) prior to use by the health-care facility staff. All other

entries reflect extrinsic sources of contamination.

Two additional gram-negative bacterial pathogens that can proliferate in moist environments are

Acinetobacter

spp. and

Enterobacter

spp.

571, 572

Members of both genera are responsible for health-

care–associated episodes of colonization, bloodstream infections, pneumonia, and urinary tract

infections among medically compromised patients, especially those in ICUs and burn therapy units.

566,

572–583

Infections caused by

Acinetobacter

spp. represent a significant clinical problem. Average

infection rates are higher from July through October compared with rates from November through

June.

584

Mortality rates associated with

Acinetobacter

bacteremia are 17%–52%, and rates as high as

71% have been reported for pneumonia caused by infection with either

Acinetobacter

spp. or

Pseudomonas

spp.

574–576

Multi-drug resistance, especially in third generation cephalosporins for

Enterobacter

spp., contributes to increased morbidity and mortality.

569, 572

Patients and health-care workers contribute significantly to the environmental contamination of surfaces

and equipment with

Acinetobacter

spp. and

Enterobacter

spp., especially in intensive care areas,

because of the nature of the medical equipment (e.g., ventilators) and the moisture associated with this

equipment.

549, 571, 572, 585

Hand carriage and hand transfer are commonly associated with health-care–

associated transmission of these organisms and for

S. marcescens

586

Enterobacter

spp. are primarily

spread in this manner among patients by the hands of health-care workers.

567, 587

Acinetobacter

spp.

have been isolated from the hands of

4%–33% of health-care workers in some studies,

585–590

and

transfer of an epidemic strain of

Acinetobacter

from patients’ skin to health-care workers’ hands has

been demonstrated experimentally.

591

Acinetobacter

infections and outbreaks have also been attributed

to medical equipment and materials (e.g., ventilators, cool mist humidifiers, vaporizers, and mist tents)

that may have contact with water of uncertain quality (e.g., rinsing a ventilator circuit in tap water).

549–

556

Strict adherence to hand hygiene helps prevent the spread of both

Acinetobacter

spp. and

Enterobacter

spp.

577, 592

Acinetobacter

spp. have also been detected on dry environmental surfaces (e.g., bed rails, counters,

sinks, bed cupboards, bedding, floors, telephones, and medical charts) in the vicinity of colonized or

infected patients; such contamination is especially problematic for surfaces that are frequently

touched.

557–564

In two studies, the survival periods of

Acinetobacter baumannii

and

Acinetobacter

calcoaceticus

on dry surfaces approximated that for

S. aureus

(e.g., 26–27 days).

593, 594

Because

Acinetobacter

spp. may come from numerous sources at any given time, laboratory investigation of

health-care–associated

Acinetobacter

infections should involve techniques to determine biotype,

antibiotype, plasmid profile, and genomic fingerprinting (i.e., macrorestriction analysis) to accurately

identify sources and modes of transmission of the organism(s).

595

c. Infections and Pseudo-Infections Due to Nontuberculous Mycobacteria

NTM are acid-fast bacilli (AFB) commonly found in potable water. NTM include both saprophytic and

opportunistic organisms. Many NTM are of low pathogenicity, and some measure of host impairment is

necessary to enhance clinical disease.

596

The four most common forms of human disease associated

with NTM are a) pulmonary disease in adults; b) cervical lymph node disease in children; c) skin, soft

tissue, and bone infections; and d) disseminated disease in immunocompromised patients.

596, 597

Person-to-person acquisition of NTM infection, especially among immunocompetent persons, does not

appear to occur, and close contacts of patients are not readily infected, despite the high numbers of

organisms harbored by such patients.

596, 598–600

NTM are spread via all modes of transmission

associated with water. In addition to health-care–associated outbreaks of clinical disease, NTM can

colonize patients in health-care facilities through consumption of contaminated water or ice or through

inhalation of aerosols.

601–605

Colonization following NTM exposure, particularly of the respiratory

tract, occurs when a patient’s local defense mechanisms are impaired; overt clinical disease does not

develop.

606

Patients may have positive sputum cultures in the absence of clinical disease.

Using tap water during patient procedures and specimen collection and in the final steps of instrument

reprocessing can result in pseudo-outbreaks of NTM contamination.

607– 609

NTM pseudo-outbreaks of

Mycobacterium chelonae, M. gordonae,

and

M. xenopi

have been associated with both bronchoscopy

and gastrointestinal endoscopy when a) tap water is used to provide irrigation to the site or to rinse off

the viewing tip

in situ

or b) the instruments are inappropriately reprocessed with tap water in the final

steps.

610– 612

Table 14. Nontuberculous mycobacteria—environmental vehicles

Vehicles associated with infections or colonizations

References

Mycobacterium abscessus

Inadequately sterilized medical instruments

613

Mycobacterium avium complex (MAC)

Potable

water

614–616

Mycobacterium chelonae

Dialysis, reprocessed dialyzers

31, 32

Inadequately-sterilized

medical

instruments, jet injectors

617, 618

Contaminated solutions

619, 620

Hydrotherapy

tanks

621

Mycobacterium fortuitum

Aerosols from showers or other water sources

605, 606

Ice

602

Inadequately sterilized medical instruments

603

Hydrotherapy

tanks

622

Mycobacterium marinum

Hydrotherapy

tanks

623

Mycobacterium ulcerans

Potable

water

624

Vehicles associated with pseudo-outbreaks

References

Mycobacterium chelonae

Potable water used during bronchoscopy and instrument

610

reprocessing

Mycobacterium fortuitum

Ice

607

Mycobacterium gordonae

Deionized

water

611

Ice

603

Laboratory solution (intrinsically contaminated)

625

Potable water ingestion prior to sputum specimen collection

626

Mycobacterium kansasii

Potable

water

627

Mycobacterium terrae

Potable

water

608

Mycobacterium xenopi

Potable water

609, 612, 627

NTM can be isolated from both natural and man-made environments. Numerous studies have identified

various NTM in municipal water systems and in hospital water systems and storage tanks.

615, 616, 624, 627–

632

Some NTM species (e.g.,

Mycobacterium xenopi

) can survive in water at 113°F (45°C), and can be

isolated from hot water taps, which can pose a problem for hospitals that lower the temperature of their

hot water systems.

627

Other NTM (e.g.,

Mycobacterium kansasii, M. gordonae, M. fortuitum

, and

chelonae

) cannot tolerate high temperatures and are associated more often with cold water lines and

taps.

629

NTM have a high resistance to chlorine; they can tolerate free chlorine concentrations of 0.05–0.2 mg/L

(0.05–0.2 ppm) found at the tap.

598, 633, 634

They are 20–100 times more resistant to chlorine compared

with coliforms; slow-growing strains of NTM (e.g.,

Mycobacterium avium

and

M. kanasii

) appear to be

more resistant to chorine inactivation compared to fast-growing NTM.

635

Slow-growing NTM species

have also demonstrated some resistance to formaldehyde and glutaraldehyde, which has posed problems

for reuse of hemodialyzers.

The ability of NTM to form biofilms at fluid-surface interfaces (e.g.,

interior surfaces of water pipes) contributes to the organisms’ resistance to chemical inactivation and

provides a microenvironment for growth and proliferation.

636, 637

d. Cryptosporidiosis

Cryptosporidium parvum

is a protozoan parasite that causes self-limiting gastroenteritis in normal hosts

but can cause severe, life-threatening disease in immunocompromised patients. First recognized as a

human pathogen in 1976,

C. parvum

can be present in natural and finished waters after fecal

contamination from either human or animal sources.

638–641

The health risks associated with drinking potable water contaminated with minimal numbers of

parvum

oocysts are unknown.

642

It remains to be determined if immunosuppressed persons are more

susceptible to lower doses of oocysts than are immunocompetent persons. One study demonstrated that

a median 50% infectious dose (ID

) of 132 oocysts of calf origin was sufficient to cause infection

among healthy volunteers.

643

In a second study, the same researchers found that oocysts obtained from

infected foals (newborn horses) were infectious for human volunteers at median ID

of 10 oocysts,

indicating that different strains or species of

Cryptosporidium

may vary in their infectivity for

humans.

644

In a small study population of 17 healthy adults with pre-existing antibody to

C. parvum

the ID

was determined to be 1,880 oocysts, more than 20-fold higher than in seronegative persons.

645

These data suggest that pre-existing immunity derived from previous exposures to

Cryptosporidium

offers some protection from infection and illness that ordinarily would result from exposure to low

numbers of oocysts.

645, 646

Oocysts, particularly those with thick walls, are environmentally resistant, but their survival under

natural water conditions is poorly understood. Under laboratory conditions, some oocysts remain viable

and infectious in cold (41°F [5°C]) for months.

641

The prevalence of

Cryptosporidium

in the U.S.

drinking water supply is notable. Two surveys of approximately 300 surface water supplies revealed

that 55%–77% of the water samples contained

Cryptosporidium

oocysts.

647, 648

Because the oocysts are

highly resistant to common disinfectants (e.g., chlorine) used to treat drinking water, filtration of the

water is important in reducing the risk of waterborne transmission. Coagulation-floculation and

sedimentation, when used with filtration, can collectively achieve approximately a 2.5 log

reduction in

the number of oocysts.

649

However, outbreaks have been associated with both filtered and unfiltered

drinking water systems (e.g., the 1993 outbreak in Milwaukee, Wisconsin that affected 400,000

people).

641, 650–652

The presence of oocysts in the water is not an absolute indicator that infection will

occur when the water is consumed, nor does the absence of detectable oocysts guarantee that infection

will not occur. Health-care–associated outbreaks of cryptosporidiosis primarily have been described

among groups of elderly patients and immunocompromised persons.

653

3. Water Systems in Health-Care Facilities

a. Basic Components and Point-of-Use Fixtures

Treated municipal water enters a health-care facility via the water mains and is distributed throughout

the building(s) by a network of pipes constructed of galvanized iron, copper, and polyvinylchloride

(PVC). The pipe runs should be as short as is practical. Where recirculation is employed, the pipe runs

should be insulated and long dead legs avoided in efforts to minimize the potential for water stagnation,

which favors the proliferation of

Legionella

spp. and NTM. In high-risk applications (e.g., PE areas for

severely immunosuppressed patients), insulated recirculation loops should be incorporated as a design

feature. Recirculation loops prevent stagnation and insulation maintains return water temperature with

minimal loss.

Each water service main, branch main, riser, and branch (to a group of fixtures) has a valve and a means

to reach the valves via an access panel.

120

Each fixture has a stop valve. Valves permit the isolation of

a portion of the water system within a facility during repairs or maintenance. Vacuum breakers and

other similar devices in the lines prevent water from back-flowing into the system. All systems that

supply water should be evaluated to determine risk for potential back siphonage and cross connections

Health-care facilities generate hot water from municipal water using a boiler system. Hot water heaters

and storage vessels for such systems should have a drainage facility at the lowest point, and the heating

element should be located as close as possible to the bottom of the vessel to facilitate mixing and to

prevent water temperature stratification. Those hot or cold water systems that incorporate an elevated

holding tank should be inspected and cleaned annually. Lids should fit securely to exclude foreign

materials.

The most common point-of-use fixtures for water in patient-care areas are sinks, faucets, aerators,

showers, and toilets; eye-wash stations are found primarily in laboratories. The potential for these

fixtures to serve as a reservoir for pathogenic microorganisms has long been recognized (Table 15).

509,

654–656

Wet surfaces and the production of aerosols facilitate the multiplication and dispersion of

microbes. The level of risk associated with aerosol production from point-of-use fixtures varies.

Aerosols from shower heads and aerators have been linked to a limited number of clusters of gram-

negative bacterial colonizations and infections, including Legionnaires disease, especially in areas

where immunocompromised patients are present (e.g., surgical ICUs, transplant units, and oncology

units).

412, 415, 656–659

In one report, clinical infection was not evident among immunocompetent persons

(e.g., hospital staff) who used hospital showers when

Legionella pneumophila

was present in the water

system.

660

Given the infrequency of reported outbreaks associated with faucet aerators, consensus has

not been reached regarding the disinfection of or removal of these devices from general use. If

additional clusters of infections or colonizations occur in high-risk patient-care areas, it may be prudent

to clean and decontaminate the aerators or to remove them.

658, 659

ASHRAE recommends cleaning and

monthly disinfection of aerators in high-risk patient-care areas as part of

Legionella

control measures.

661

Although aerosols are produced with toilet flushing,

662, 663

no epidemiologic evidence suggests that

these aerosols pose a direct infection hazard.

Although not considered a standard point-of-use fixture, decorative fountains are being installed in

increasing numbers in health-care facilities and other public buildings. Aerosols from a decorative

fountain have been associated with transmission of

Legionella pneumophila

serogroup 1 infection to a

small cluster of older adults.

664

This hotel lobby fountain had been irregularly maintained, and water in

the fountain may have been heated by submersed lighting, all of which favored the proliferation of

Legionella

in the system.

664

Because of the potential for generations of infectious aerosols, a prudent

prevention measure is to avoid locating these fixtures in or near high-risk patient-care areas and to

adhere to written policies for routine fountain maintenance.

120

Table 15. Water and point-of-use fixtures as sources and reservoirs of waterborne
pathogens*

Reservoir

Associated

pathogens

Transmission

Strength of

evidence+

Prevention and

control

References

Potable water

Pseudomonas

, gram-

negative bacteria,

NTM

Contact

Moderate

Follow public health

guidelines.

(See Tables

12–14)

Reservoir

Associated

pathogens

Transmission

Strength of

evidence+

Prevention and

control

References

Potable water

Legionella

Aerosol

inhalation

Moderate Provide

supplemental

treatment for water.

(See Table

11)

Holy water

Gram-negative

bacteria

Contact

Low

Avoid contact with

severe burn injuries.

Minimize use among

immunocompromised

patients.

665

Dialysis water

Gram-negative

bacteria

Contact

Moderate

Dialysate should be

<2,000 cfu/mL; water

should be <200 cfu/mL.

2, 527, 666–

668

Automated

endoscope

reprocessors

and rinse water

Gram-negative

bacteria

Contact

Moderate

Use and maintain

equipment according to

instructions; eliminate

residual moisture by

drying the channels

(e.g., through alcohol

rinse and forced air

drying).

669–675

Water baths

Pseudomonas,
Burkholderia,
Acinetobacter

Contact

Moderate

Add germicide to the

water; wrap transfusion

products in protective

plastic wrap if using the

bath to modulate the

temperature of these

products.

29, 533, 676,

677

Tub immersion

Pseudomonas,
Enterobacter,
Acinetobacter

Contact

Moderate

Drain and disinfect tub

after each use; consider

adding germicide to the

water; water in large

hydrotherapy pools

should be properly

disinfected and filtered.

678–683

Ice and ice

machines

NTM,

Enterobacter,

Pseudomonas,
Cryptosporidium

Legionella

Ingestion, contact

Moderate

Low

Clean periodically; use

automatic dispenser

(avoid open chest

storage compartments

in patient areas).

601, 684–687

Faucet aerators

Legionella

Aerosol inhalation

Moderate

Clean and disinfect

monthly in high-risk

patient areas; consider

removing if additional

infections occur.

415, 661

Faucet aerators

Pseudomonas,
Acinetobacter,
Stenotrophomonas,
Chryseobacterium

Contact, droplet

Low

No precautions are

necessary at present in

immunocompetent

patient-care areas.

658, 659,

688, 689

Sinks

Pseudomonas

Contact,

droplet

Moderate

Use separate sinks for

handwashing and

disposal of

contaminated fluids.

509, 653,

685–693

Showers

Legionella

Aerosol inhalation

Low

Provide sponge baths

for hematopoietic stem

cell transplant patients;

avoid shower use for

immunocompromised

patients when

Legionella

is detected

in facility water.

656

Reservoir

Associated

pathogens

Transmission

Strength of

evidence+

Prevention and

control

References

Dental unit

water lines

Pseudomonas,
Legionella,
Sphingomonas,
Acinetobacter

Contact

Low

Clean water systems

according to system

manufacturer’s

instructions.

636, 694–696

Ice baths for

thermodilution

catheters

Ewingella,
Staphylococcus

Contact

Low

Use sterile water.

697, 698

Decorative

fountains

Legionella

Aerosol inhalation

Low

Perform regular

maintenance, including

water disinfection;

avoid use in or near

high-risk patient-care

areas.

664

Eyewash

stations

Pseudomonas,

amoebae,

Legionella

Contact Low

Minimum

Flush eyewash stations

weekly; have sterile

water available for eye

flushes.

518, 699, 700

Toilets Gram-negative

bacteria

– Minimum

Clean

regularly;

use

good hand hygiene.

662

Flowers Gram-negative

bacteria,

Aspergillus

–

Minimum

Avoid use in intensive

care units and in

immunocompromised

patient-care settings.

515, 701, 702

* Modified from reference 654 and used with permission of the publisher (Slack, Inc.)

Moderate:

occasional well-described outbreaks.

Low:

few well-described outbreaks.

Minimal:

actual infections not demonstrated.

b. Water Temperature and Pressure

Hot water temperature is usually measured at the point of use or at the point at which the water line

enters equipment requiring hot water for proper operation.

120

Generally, the hot water temperature in

hospital patient-care areas is no greater than a temperature within the range of 105°F–120°F (40.6°C–

49°C), depending on the AIA guidance issued at the year in which the facility was built.

120

Hot water

temperature in patient-care areas of skilled nursing-care facilities is set within a slightly lower range of

95°F–110°F (35°C–43.3°C) depending on the AIA guidance at the time of facility construction.

120

Many states have adopted a temperature setting in these ranges into their health-care regulations and

building codes. ASHRAE, however, has recommended higher settings.

661

Steam jets or booster heaters

are usually needed to meet the hot water temperature requirements in certain service areas of the

hospital (e.g., the kitchen [120°F (49°C)] or the laundry [160°F (71°C)]).

120

Additionally, water lines

may need to be heated to a particular temperature specified by manufacturers of specific hospital

equipment. Hot-water distribution systems serving patient-care areas are generally operated under

constant recirculation to provide continuous hot water at each hot-water outlet.

120

If a facility is or has

a hemodialysis unit, then continuously circulated, cold treated water is provided to that unit.

120

To minimize the growth and persistence of gram-negative waterborne bacteria (e.g., thermophilic NTM

and

Legionella

spp.),

627, 703–709

cold water in health-care facilities should be stored and distributed at

temperatures below 68°F (20°C); hot water should be stored above 140°F (60°C) and circulated with a

minimum return temperature of 124°F (51°C),

661

or the highest temperature specified in state

regulations and building codes. If the return temperature setting of 124°F (51°C) is permitted, then

installation of preset thermostatic mixing valves near the point-of-use can help to prevent scalding.

Valve maintenance is especially important in preventing valve failure, which can result in scalding.

New shower systems in large buildings, hospitals, and nursing homes should be designed to permit

mixing of hot and cold water near the shower head. The warm water section of pipe between the control

valve and shower head should be self-draining. Where buildings can not be retrofitted, other

approaches to minimize the growth of

Legionella

spp. include a) periodically increasing the temperature

to at least 150°F [66°C] at the point of use [i.e., faucets] and b) adding additional chlorine and flushing

the water.

661, 710, 711

Systems should be inspected annually to ensure that thermostats are functioning

properly.

Adequate water pressure ensures sufficient water supplies for a) direct patient care; b) operation of

water-cooled instruments and equipment [e.g., lasers, computer systems, telecommunications systems,

and automated endoscope reprocessors

712

]; c) proper function of vacuum suctioning systems; d) indoor

climate control; and e) fire-protection systems. Maintaining adequate pressure also helps to ensure the

integrity of the piping system.

c. Infection-Control Impact of Water System Maintenance and Repair

Corrective measures for water-system failures have not been studied in well-designed experiments;

these measures are instead based on empiric engineering and infection-control principles. Health-care

facilities can occasionally sustain both intentional cut-offs by the municipal water authority to permit

new construction project tie-ins and unintentional disruptions in service when a water main breaks as a

result of aging infrastructure or a construction accident. Vacuum breakers or other similar devices can

prevent backflow of water in the facility’s distribution system during water-disruption emergencies.

To be prepared for such an emergency, all health-care facilities need contingency plans that identify a)

the total demand for potable water, b) the quantity of replacement water [e.g., bottled water] required for

a minimum of 24 hours when the water system is down, c) mechanisms for emergency water

distribution, and 4) procedures for correcting drops in water pressure that affect operation of essential

devices and equipment that are driven or cooled by a water system [Table 16].

713

Table 16. Water demand in health-care facilities during water disruption emergencies

Potable water

Bottled, sterile water

Water use needs

Drinking water

Handwashing

Cafeteria services

Ice

Manual flushing of toilets

Patient baths, hygiene

Hemodialysis

Hydrotherapy

Fire prevention (e.g., sprinkler systems)

Surgery and critical care areas

Laboratory services

Laundry and central sterile services*

Cooling towers+

Steam generation

Surgical scrub

Emergency surgical procedures

Pharmaceutical preparations

Patient-care equipment (e.g., ventilators)§

* Arrange to have a contingency provision of these services from another resource, if possible (e.g., another health-care facility or contractor).

+ Some cooling towers may use a potable water source, but most units use non-potable water.

§ This item is included in the table under the assumption that electrical power is available during the water emergency.

Detailed, up-to-date plans for hot and cold water piping systems should be readily available for

maintenance and repair purposes in case of system problems. Opening potable water systems for repair

or construction and subjecting systems to water-pressure changes can result in water discoloration and

dramatic increases in the concentrations of

Legionella

spp. and other gram-negative bacteria. The

maintenance of a chlorine residual at all points within the piping system also offers some protection

from entry of contamination to the pipes in the event of inadvertent cross-connection between potable

and non-potable water lines. As a minimum preventive measure, ASHRAE recommends a thorough

flushing of the system.

661

High-temperature flushing or hyperchlorination may also be appropriate

strategies to decrease potentially high concentrations of waterborne organisms. The decision to pursue

either of these remediation strategies, however, should be made on a case-by-case basis. If only a

portion of the system is involved, high temperature flushing or chlorination can be used on only that

portion of the system.

661

When shock decontamination of hot water systems is necessary (e.g., after disruption caused by

construction and after cross-connections), the hot water temperature should be raised to 160°F–170°F

(71°C–77°C) and maintained at that level while each outlet around the system is progressively flushed.

A minimum flush time of 5 minutes has been recommended;

the optimal flush time is not known,

however, and longer flush times may be necessary.

714

The number of outlets that can be flushed

simultaneously depends on the capacity of the water heater and the flow capability of the system.

Appropriate safety procedures to prevent scalding are essential. When possible, flushing should be

performed when the fewest building occupants are present (e.g., during nights and weekends).

When thermal shock treatment is not possible, shock chlorination may serve as an alternative method.

661

Experience with this method of decontamination is limited, however, and high levels of free chlorine

can corrode metals. Chlorine should be added, preferably overnight, to achieve a free chlorine residual

of at least 2 mg/L (2 ppm) throughout the system.

661

This may require chlorination of the water heater

or tank to levels of 20–50 mg/L (20–50 ppm). The pH of the water should be maintained at 7.0–8.0.

661

After completion of the decontamination, recolonization of the hot water system is likely to occur unless

proper temperatures are maintained or a procedure such as continuous supplemental chlorination is

continued.

Interruptions of the water supply and sewage spills are situations that require immediate recovery and

remediation measures to ensure the health and safety of patients and staff.

715

When delivery of potable

water through the municipal distribution system has been disrupted, the public water supplier must issue

a “boil water” advisory if microbial contamination presents an immediate public health risk to

customers. The hospital engineer should oversee the restoration of the water system in the facility and

clear it for use when appropriate. Hospitals must maintain a high level of surveillance for waterborne

disease among patients and staff after the advisory is lifted.

642

Flooding from either external (e.g., from a hurricane) or internal sources (e.g., a water system break)

usually results in property damage and a temporary loss of water and sanitation.

716–718

JCAHO requires

all hospitals to have plans that address facility response for recovery from both internal and external

disasters.

713, 719

The plans are required to discuss a) general emergency preparedness, b) staffing, c)

regional planning among area hospitals, d) emergency supply of potable water, e) infection control and

medical services needs, f) climate control, and g) remediation. The basic principles of structural

recovery from flooding are similar to those for recovery from sewage contamination (Box 9 and 10).

Following a major event (e.g., flooding), facilities may elect to conduct microbial sampling of water

after the system is restored to verify that water quality has been returned to safe levels (<500 CFU/mL,

heterotrophic plate count). This approach may help identify point-of-use fixtures that may harbor

contamination as a result of design or engineering features.

720

Medical records should be allowed to

dry and then either photocopied or placed in plastic covers before returning them to the record.

Moisture meters can be used to assess water-damaged structural materials. If porous structural materials

for walls have a moisture content of >20% after 72 hours, the affected material should be removed.

266,

278, 313

The management of water-damaged structural materials is not strictly limited to major water

catastrophes (e.g., flooding and sewage intrusions); the same principles are used to evaluate the damage

from leaking roofs, point-of-use fixtures, and equipment. Additional sources of moisture include

condensate on walls from boilers and poorly engineered humidification in HVAC systems.

Box 9. Recovery and remediation measures for water-related emergencies*

Potable water disruptions

Contingency plan items

Ensure access to plumbing network so that repairs can be easily made.

Provide sufficient potable water, either from bottled sources or truck delivery.

Post advisory notices against consuming tap water, ice, or beverages made with water.

Rope off or bag drinking fountains to designate these as being “out of service” until further notice.

Rinse raw foods as needed in disinfected water.

Disconnect ice machines whenever possible.+

Postpone laundry services until after the water system is restored.

Water treatment

Heat water to a rolling boil for >1 minute.

Remediation of the water system after the “boil water” advisory is rescinded

Flush fixtures (e.g., faucets and drinking fountains) and equipment for several minutes and restart.

Run water softeners through a regeneration cycle.

Drain, disinfect, and refill water storage tanks, if needed.

Change pretreatment filters and disinfect the dialysis water system.

Sewage spills/malfunction

Overall strategy

Move patients and clean/sterile supplies out of the area.

Redirect traffic away from the area.

Close the doors or use plastic sheeting to isolate the area prior to clean-up.

Restore sewage system function first, then the potable water system (if both are malfunctioning).

Remove sewage solids, drain the area, and let dry.

Remediation of the structure

Hard surfaces: clean with detergent/disinfectant after the area has been drained.

Carpeting, loose tiles, buckled flooring: remove and allow the support surface to dry; replace the items; wet down

carpeting with a low-level disinfectant or sanitizer prior to removal to minimize dust dispersion to the air.

Wallboard and other porous structural materials: remove and replace if they cannot be cleaned and dried within

72 hours.§

Furniture

Hard surface furniture (e.g., metal or plastic furniture): clean and allow to dry.

Wood furniture: let dry, sand the wood surface, and reapply varnish.

Cloth furniture: replace.

Electrical equipment

Replace if the item cannot be easily dismantled, cleaned, and reassembled.

* Material in this box is compiled from references 266, 278, 315, 713, 716–719, 721–729.

+ Ice machines should always be disconnected from the water source in advance of planned water disruptions.

§ Moisture meter readings should be <20% moisture content.

An exception to these recommendations is made for hemodialysis units where water is further

treated either by portable water treatment or large-scale water treatment systems usually involving

reverse osmosis (RO). In the United States, >97% of dialysis facilities use RO treatment for their

water.

721

However, changing pre-treatment filters and disinfecting the system to prevent colonization

of the RO membrane and microbial contamination down-stream of the pre-treatment filter are prudent

measures.

Box 10. Contingency planning for flooding

General emergency preparedness

Ensure that emergency electrical generators are not located in flood-prone areas of the facility.

Develop alternative strategies for moving patients, water containers, medical records, equipment, and supplies in the

event that the elevators are inoperable.

Establish in advance a centralized base of operations with batteries, flashlights, and cellular phones.

Ensure sufficient supplies of sandbags to place at the entrances and the area around boilers, incinerators, and

generators.

Establish alternative strategies for bringing core employees to the facility if high water prevents travel.

Staffing Patterns

Temporarily reassign licensed staff as needed to critical care areas to provide manual ventilation and to perform

vital assessments on patients.

Designate a core group of employees to remain on site to keep all services operational if the facility remains open.

Train all employees in emergency preparedness procedures.

Regional planning among are facilities for disaster management

Incorporate community support and involvement (e.g., media alerts, news, and transportation).

Develop in advance strategies for transferring patients, as needed.

Develop strategies for sharing supplies and providing essential services among participating facilities (e.g., central

sterile department services, and laundry services).

Identify sources for emergency provisions (e.g., blood, emergency vehicles, and bottled water).

Medical services and infection control

Use alcohol-based hand rubs in general patient-care areas.

Postpone elective surgeries until full services are restored, or transfer these patients to other facilities.

Consider using portable dialysis machines.+

Provide an adequate supply of tetanus and hepatitis A immunizations for patients and staff.

Climate control

Provide adequate water for cooling towers.§

* Material in this box was compiled from references 713, 716–719.

+ Portable dialysis machines require less water compared to the larger units situated in dialysis settings.

§ Water for cooling towers may need to be trucked in, especially if the tower uses a potable water source.

4. Strategies for Controlling Waterborne Microbial Contamination

a. Supplemental Treatment of Water with Heat and/or Chemicals

In addition to using supplemental treatment methods as remediation measures after inadvertent

contamination of water systems, health-care facilities sometimes use special measures to control

waterborne microorganisms on a sustained basis. This decision is most often associated with outbreaks

of legionellosis and subsequent efforts to control legionellae,

722

although some facilities have tried

supplemental measures to better control thermophilic NTM.

627

The primary disinfectant for both cold and hot water systems is chlorine. However, chlorine residuals

are expected to be low, and possibly nonexistent, in hot water tanks because of extended retention time

in the tank and elevated water temperature. Flushing, especially that which removes sludge from the

bottom of the tank, probably provides the most effective treatment of water systems. Unlike the

situation for disinfecting cooling towers, no equivalent recommendations have been made for potable

water systems, although specific intervention strategies have been published.

403, 723

The principal

approaches to disinfection of potable systems are heat flushing using temperatures 160°F–170°F (71°–

77°C), hyperchlorination, and physical cleaning of hot-water tanks.

3, 403, 661

Potable systems are easily

recolonized and may require continuous intervention (e.g., raising of hot water temperatures or

continuous chlorination).

403, 711

Chlorine solutions lose potency over time, thereby rendering the

stocking of large quantities of chlorine impractical.

Some hospitals with hot water systems identified as the source of

Legionella

spp. have performed

emergency decontamination of their systems by pulse (i.e., one-time) thermal disinfection/superheating

or hyperchlorination.

711, 714, 724, 725

After either of these procedures, hospitals either maintain their

heated water with a minimum return temperature of 124°F (51°C) and cold water at <68°F (<20°C) or

chlorinate their hot water to achieve 1–2 mg/L (1–2 ppm) of free residual chlorine at the tap.

26, 437, 709–711,

726, 727

Additional measures (e.g., physical cleaning or replacement of hot-water storage tanks, water

heaters, faucets, and shower heads) may be required to help eliminate accumulations of scale and

sediment that protect organisms from the biocidal effects of heat and chlorine.

457, 711

Alternative

methods for controlling and eradicating legionellae in water systems (e.g., treating water with chlorine

dioxide, heavy metal ions [i.e., copper/silver ions], ozone, and UV light) have limited the growth of

legionellae under laboratory and operating conditions.

728–742

Further studies on the long-term efficacy

of these treatments are needed before these methods can be considered standard applications.

Renewed interest in the use of chloramines stems from concerns about adverse health effects associated

with disinfectants and disinfection by-products.

743

Monochloramine usage minimizes the formation of

disinfection by-products, including trihalomethanes and haloacetic acids. Monochloramine can also

reach distal points in a water system and can penetrate into bacterial biofilms more effectively than free

chlorine.

744

However, monochloramine use is limited to municipal water treatment plants and is

currently not available to health-care facilities as a supplemental water-treatment approach. A recent

study indicated that 90% of Legionnaires disease outbreaks associated with drinking water could have

been prevented if monochloramine rather than free chlorine has been used for residual disinfection.

745

In a retrospective comparison of health-care–associated Legionnaires disease incidence in central Texas

hospitals, the same research group documented an absence of cases in facilities located in communities

with monochloramine-treated municipal water.

746

Additional data are needed regarding the

effectiveness of using monochloramine before its routine use as a disinfectant in water systems can be

recommended. No data have been published regarding the effectiveness of monochloramine installed at

the level of the health-care facility.

Additional filtration of potable water systems is not routinely necessary. Filters are used in water lines

in dialysis units, however, and may be inserted into the lines for specific equipment (e.g., endoscope

washers and disinfectors) for the purpose of providing bacteria-free water for instrument reprocessing.

Additionally, an RO unit is usually added to the distribution system leading to PE areas.

b. Primary Prevention of Legionnaires Disease (No Cases Identified)

The primary and secondary environmental infection-control strategies described in this section on the

guideline pertain to health-care facilities without transplant units. Infection-control measures specific to

PE or transplant units (i.e., patient-care areas housing patients at the highest risk for morbidity and

mortality from

Legionella

spp. infection) are described in the subsection titled

Preventing Legionnaires

Disease in Protective Environments

Health-care facilities use at least two general strategies to prevent health-care–associated legionellosis

when no cases or only sporadic cases have been detected. The first is an environmental surveillance

approach involving periodic culturing of water samples from the hospital’s potable water system to

monitor for

Legionella

spp.

747–750

If any sample is culture-positive, diagnostic testing is recommended

for all patients with health-care–associated pneumonia.

748, 749

In-house testing is recommended for

facilities with transplant programs as part of a comprehensive treatment/management program. If >30%

of the samples are culture-positive for

Legionella

spp., decontamination of the facility’s potable water

system is warranted.

748

The premise for this approach is that no cases of health-care–associated

legionellosis can occur if

Legionella

spp. are not present in the potable water system, and, conversely,

cases of health-care–associated legionellosis could potentially occur if

Legionella

spp. are cultured

from

the water.

26, 751

Physicians who are informed that the hospital’s potable water system is culture-positive

for

Legionella

spp. are more likely to order diagnostic tests for legionellosis.

A potential advantage of the environmental surveillance approach is that periodic culturing of water is

less costly than routine laboratory diagnostic testing for all patients who have health-care–associated

pneumonia. The primary argument against this approach is that, in the absence of cases, the relationship

between water-culture results and legionellosis risk remains undefined.

Legionnella

spp. can be

present in the water systems of buildings

752

without being associated with known cases of disease.

437, 707,

753

In a study of 84 hospitals in Québec, 68% of the water systems were found to be colonized with

Legionella

spp., and 26% were colonized at >30% of sites sampled; cases of Legionnaires disease,

however, were infrequently reported from these hospitals.

707

Other factors also argue against environmental surveillance. Interpretation of results from periodic

water culturing might be confounded by differing results among the sites sampled in a single water

system and by fluctuations in the concentration of

Legionella

spp. at the same site.

709, 754

In addition,

the risk for illness after exposure to a given source might be influenced by several factors other than the

presence or concentration of organisms, including a) the degree to which contaminated water is

aerosolized into respirable droplets, b) the proximity of the infectious aerosol to the potential host, c) the

susceptibility of the host, and d) the virulence properties of the contaminating strain.

755–757

Thus, data

are insufficient to assign a level of disease risk even on the basis of the number of colony-forming units

detected in samples from areas for immunocompetent patients. Conducting environmental surveillance

would obligate hospital administrators to initiate water-decontamination programs if

Legionella

spp. are

identified. Therefore, periodic monitoring of water from the hospital's potable water system and from

aerosol-producing devices is not widely recommended in facilities that have not experienced cases of

health-care–associated legionellosis.

661, 758

The second strategy to prevent and control health-care–associated legionellosis is a clinical approach, in

which providers maintain a high index of suspicion for legionellosis and order appropriate diagnostic

tests (i.e., culture, urine antigen, and direct fluorescent antibody [DFA] serology) for patients with

health-care–associated pneumonia who are at high risk for legionellosis and its complications.

437, 759, 760

The testing of autopsy specimens can be included in this strategy should a death resulting from health-

care–associated pneumonia occur. Identification of one case of definite or two cases of possible health-

care–associated Legionnaires disease should prompt an epidemiologic investigation for a hospital

source of

Legionella

spp., which may involve culturing the facility’s water for

Legionella

. Routine

maintenance of cooling towers, and use of sterile water for the filling and terminal rinsing of

nebulization devices and ventilation equipment can help to minimize potential sources of contamination.

Circulating potable water temperatures should match those outlined in the subsection titled

Water

Temperature and Pressure

, as permitted by state code.

c. Secondary prevention of Legionnaires Disease (With Identified Cases)

The indications for a full-scale environmental investigation to search for and subsequently

decontaminate identified sources of

Legionella

spp. in health-care facilities without transplant units

have not been clarified; these indications would likely differ depending on the facility. Case categories

for health-care–associated Legionnaires disease in facilities without transplant units include definite

cases (i.e., laboratory-confirmed cases of legionellosis that occur in patients who have been hospitalized

continuously for >10 days before the onset of illness) and possible cases (i.e., laboratory-confirmed

infections that occur 2–9 days after hospital admission).

In settings in which as few as one to three

health-care–associated cases are recognized over several months, intensified surveillance for

Legionnaires disease has frequently identified numerous additional cases.

405, 408, 432, 453, 739, 759, 760

This

finding suggests the need for a low threshold for initiating an investigation after laboratory confirmation

of cases of health-care–associated legionellosis. When developing a strategy for responding to such a

finding, however, infection-control personnel should consider the level of risk for health-care–

associated acquisition of, and mortality from,

Legionella

spp. infection at their particular facility.

An epidemiologic investigation conducted to determine the source of

Legionella

spp. involves several

important steps (Box 11). Laboratory assessment is crucial in supporting epidemiologic evidence of a

link between human illness and a specific environmental source.

761

Strain determination from subtype

analysis is most frequently used in these investigations.

410, 762–764

Once the environmental source is

established and confirmed with laboratory support, supplemental water treatment strategies can be

initiated as appropriate.

Box 11. Steps in an epidemiologic investigation for legionellosis

Review medical and microbiologic records.

Initiate active surveillance to identify all recent or ongoing cases.

Develop a line listing of cases by time, place, and person.

Determine the type of epidemiologic investigation needed for assessing risk factors:

• Case-control study,
• Cohort study.

Gather and analyze epidemiologic information:

• Evaluate risk factors associated with potential environmental exposures (e.g., showers,
cooling towers, and respiratory-therapy equipment).
Collect

water

samples:

• Sample environmental sources implicated by epidemiologic investigation,

•

Sample other potential source of water aerosols.

Subtype strains of Legionella spp. cultured from both patients and environmental sources.

Review autopsy records and include autopsy specimens in diagnostic testing.

The decision to search for hospital environmental sources of

Legionella

spp. and the choice of

procedures to eradicate such contamination are based on several considerations, as follows: a) the

hospital’s patient population; b) the cost of an environmental investigation and institution of control

measures to eradicate

Legionella

spp. from the water supply;

765–768

and c) the differential risk, based on

host factors, for acquiring health-care–associated legionellosis and developing severe and fatal

infection.

d. Preventing Legionnaires Disease in Protective Environments

This subsection outlines infection-control measures applicable to those health-care facilities providing

care to severely immunocompromised patients. Indigenous microorganisms in the tap water of these

facilities may pose problems for such patients. These measures are designed to prevent the generation

of potentially infectious aerosols from water and the subsequent exposure of PE patients or other

immunocompromised patients (e.g., transplant patients) (Table 17). Infection-control measures that

address the use of water with medical equipment (e.g., ventilators, nebulizers, and equipment

humidifiers) are described in other guidelines and publications.

3, 455

If one case of laboratory-confirmed, health-care–associated Legionnaires disease is identified in a

patient in a solid-organ transplant program or in PE (i.e., an inpatient in PE for all or part of the 2–10

days prior to onset of illness) or if two or more laboratory-confirmed cases occur among patients who

had visited an outpatient PE setting, the hospital should report the cases to the local and state health

departments. The hospital should then initiate a thorough epidemiologic and environmental

investigation to determine the likely environmental sources of

Legionella

spp.

The source of

Legionella

should be decontaminated or removed. Isolated cases may be difficult to investigate.

Because transplant recipients are at substantially higher risk for disease and death from legionellosis

compared with other hospitalized patients, periodic culturing for

Legionella

spp. in water samples from

the potable water in the solid-organ transplant and/or PE unit can be performed as part of an overall

strategy to prevent Legionnaires disease in PE units.

9, 431, 710, 769

The optimal methodology (i.e.,

frequency and number of sites) for environmental surveillance cultures in PE units has not been

determined, and the cost-effectiveness of this strategy has not been evaluated. Because transplant

recipients are at high risk for Legionnaires disease and because no data are available to determine a safe

concentration of legionellae organisms in potable water, the goal of environmental surveillance for

Legionella

spp. should be to maintain water systems with no detectable organisms.

9, 431

Culturing for

legionellae may be used to assess the effectiveness of water treatment or decontamination methods, a

practice that provides benefits to both patients and health-care workers.

767, 770

Table 17. Additional infection-control measures to prevent exposure of high-risk patients
to waterborne pathogens

Measures References

• Restrict patients from taking showers if the water is contaminated with

Legionella

spp.

• Use water that is not contaminated with

Legionella

spp. for patients’ sponge baths.

• Provide sterile water for drinking, tooth brushing, or for flushing nasogastric tubes.

• Perform supplemental treatment of the water for the unit.

• Consider periodic monitoring (i.e., culturing) of the unit water supply for

Legionella

spp.

• Remove shower heads and faucet aerators monthly for cleaning.*

• Use a 500–600 ppm (1:100 v/v dilution) solution of sodium hypochlorite to

disinfect shower heads and faucet aerators.*

• Do not use large-volume room air humidifiers that create aerosols unless these are

subjected to cleaning and high-level disinfection daily and filled with distilled

water.

• Eliminate water-containing bath toys.+

• 407, 412, 654, 655, 658

• 9

• 9, 412

• 732

• 9, 431

• 661

• 3

• 30

* These measures can be considered in settings where legionellosis cases have occurred. These measures are not generally recommended in

routine patient-care setting..

+ These items have been associated with outbreaks of

Pseudomonas

Protecting patient-care devices and instruments from inadvertent tap water contamination during room

cleaning procedures is also important in any immunocompromised patient-care area. In a recent

outbreak of gram-negative bacteremias among open-heart-surgery patients, pressure-monitoring

equipment that was assembled and left uncovered overnight prior to the next day’s surgeries was

inadvertently contaminated with mists and splashing water from a hose-disinfectant system used for

cleaning.

771

5. Cooling Towers and Evaporative Condensers

Modern health-care facilities maintain indoor climate control during warm weather by use of cooling

towers (large facilities) or evaporative condensers (smaller buildings). A cooling tower is a wet-type,

evaporative heat transfer device used to discharge to the atmosphere waste heat from a building’s air

conditioning condensers (Figure 5).

772, 773

Warm water from air-conditioning condensers is piped to the

cooling tower where it is sprayed downward into a counter- or cross-current air flow. To accelerate heat

transfer to the air, the water passes over the fill, which either breaks water into droplets or causes it to

spread into a thin film.

772, 773

Most systems use fans to move air through the tower, although some large

industrial cooling towers rely on natural draft circulation of air. The cooled water from the tower is

piped back to the condenser, where it again picks up heat generated during the process of chilling the

system’s refrigerant. The water is cycled back to the cooling tower to be cooled. Closed-circuit cooling

towers and evaporative condensers are also evaporative heat-transfer devices. In these systems, the

process fluid (e.g., water, ethylene glycol/water mixture, oil, or a condensing refrigerant) does not

directly contact the cooling air, but is contained inside a coil assembly.

661

Figure 5. Diagram of a typical air conditioning (induced draft) cooling tower*

Water temperatures are approximate and may differ substantially according to system use and design. Warm water from the

condenser (or chiller) is sprayed downward into a counter- or cross-current air flow. Water passes over the fill (a component of

the system designed to increase the surface area of the water exposed to air), and heat from the water is transferred to the air.

Some of the water becomes aerosolized during this process, although the volume of aerosol discharged to the air can be

reduced by the placement of a drift eliminator. Water cooled in the tower returns to the heat source to cool refrigerant from the

air conditioning unit.

* This figure is reprinted with permission of the publisher of reference 773 (Plenum Medical).

Cooling towers and evaporative condensers incorporate inertial stripping devices called drift eliminators

to remove water droplets generated within the unit. Although the effectiveness of these eliminators

varies substantially depending on design and condition, some water droplets in the size range of <5 µm

will likely leave the unit, and some larger droplets leaving the unit may be reduced to <5 µm by

evaporation. Thus, even with proper operation, a cooling tower or evaporative condenser can generate

and expel respirable water aerosols. If either the water in the unit’s basin or the make-up water (added

to replace water lost to evaporation) contains

Legionella

spp. or other waterborne microorganisms, these

organisms can be aerosolized and dispersed from the unit.

774

Clusters of both Legionnaires disease and

Pontiac fever have been traced to exposure to infectious water aerosols originating from cooling towers

and evaporative condensers contaminated with

Legionella

spp. Although most of these outbreaks have

been community-acquired episodes of pneumonia,

775–782

health-care–associated Legionnaires disease

has been linked to cooling tower aerosol exposure.

404, 405

Contaminated aerosols from cooling towers

on hospital premises gained entry to the buildings either through open windows or via air handling

system intakes located near the tower equipment.

Cooling towers and evaporative condensers provide ideal ecological niches for

Legionella

spp. The

typical temperature of the water in cooling towers ranges from 85°F–95°F (29°C–35°C), although

temperatures can be above 120°F (49°C) and below 70°F (21°C) depending on system heat load,

ambient temperature, and operating strategy.

661

An Australian study of cooling towers found that

legionellae colonized or multiplied in towers with basin temperatures above 60.8°F (16°C), and

multiplication became explosive at temperatures above 73.4°F (23°C).

783

Water temperature in closed-

circuit cooling towers and evaporative condensers is similar to that in cooling towers. Considerable

variation in the piping arrangement occurs. In addition, stagnant areas or dead legs may be difficult to

clean or penetrate with biocides.

Several documents address the routine maintenance of cooling towers, evaporative condensers, and

whirlpool spas.

661, 784–787

They suggest following manufacturer's recommendations for cleaning and

biocide treatment of these devices; all health-care facilities should ensure proper maintenance for their

cooling towers and evaporative condensers, even in the absence of

Legionella

spp (Appendix C).

Because cooling towers and evaporative condensers can be shut down during periods when air

conditioning is not needed, this maintenance cleaning and treatment should be performed before starting

up the system for the first time in the warm season.

782

Emergency decontamination protocols

describing cleaning procedures and hyperchlorination for cooling towers have been developed for

towers implicated in the transmission of legionellosis.

786, 787

6. Dialysis Water Quality and Dialysate

a. Rationale for Water Treatment in Hemodialysis

Hemodialysis, hemofiltration, and hemodiafiltration require special water-treatment processes to

prevent adverse patient outcomes of dialysis therapy resulting from improper formulation of dialysate

with water containing high levels of certain chemical or biological contaminants. The Association for

the Advancement of Medical Instrumentation (AAMI) has established chemical and microbiologic

standards for the water used to prepare dialysate, substitution fluid, or to reprocess hemodialyzers for

renal replacement therapy.

788–792

The AAMI standards address: a) equipment and processes used to

purify water for the preparation of concentrates and dialysate and the reprocessing of dialyzers for

multiple use and b) the devices used to store and distribute this water. Future revisions to these

standards may include hemofiltration and hemodiafiltration

Water treatment systems used in hemodialysis employ several physical and/or chemical processes either

singly or in combination (Figure 6). These systems may be portable units or large systems that feed

several rooms. In the United States, >97% of maintenance hemodialysis facilities use RO alone or in

combination with deionization.

793

Many acute-care facilities use portable hemodialysis machines with

attached portable water treatment systems that use either deionization or RO. These machines were

exempted from earlier versions of AAMI recommendations, but given current knowledge about toxic

exposures to and inflammatory processes in patients new to dialysis, these machines should now come

into compliance with current AAMI recommendations for hemodialysis water and dialysate quality.

788,

789

Previous recommendations were based on the assumption that acute-care patients did not

experience the same degree of adverse effects from short-term, cumulative exposures to either

chemicals or microbiologic agents present in hemodialysis fluids compared with the effects encountered

by patients during chronic, maintenance dialysis.

788, 789

Additionally, JCAHO is reviewing inpatient

practices and record-keeping for dialysis (acute and maintenance) for adherence to AAMI standards and

recommended practices.

Figure 6. Dialysis water treatment system*

* See text for description of the placement and function of these components.

Neither the water used to prepare dialysate nor the dialysate itself needs to be sterile, but tap water can

not be used without additional treatment. Infections caused by rapid-growing NTM (e.g.,

Mycobacterium chelonae

and

M. abscessus

) present a potential risk to hemodialysis patients (especially

those in hemodialyzer reuse programs) if disinfection procedures to inactivate mycobacteria in the water

(low-level disinfection) and the hemodialyzers (high-level disinfection) are inadequate.

31, 32, 633

Other

factors associated with microbial contamination in dialysis systems could involve the water treatment

system, the water and dialysate distribution systems, and the type of hemodialyzer.

666, 667, 794–799

Understanding the various factors and their influence on contamination levels is the key to preventing

high levels of microbial contamination in dialysis therapy.

In several studies, pyrogenic reactions were demonstrated to have been caused by lipopolysaccharide or

endotoxin associated with gram-negative bacteria.

794, 800–803

Early studies demonstrated that parenteral

exposure to endotoxin at a concentration of 1 ng/kg body weight/hour was the threshold dose for

producing pyrogenic reactions in humans, and that the relative potencies of endotoxin differ by bacterial

species.

804, 805

Gram-negative water bacteria (e.g.,

Pseudomonas

spp.) have been shown to multiply

rapidly in a variety of hospital-associated fluids that can be used as supply water for hemodialysis (e.g.,

distilled water, deionized water, RO water, and softened water) and in dialysate (a balanced salt solution

made with this water).

806

Several studies have demonstrated that the attack rates of pyrogenic reactions

are directly associated with the number of bacteria in dialysate.

666, 667, 807

These studies provided the

rationale for setting the heterotrophic bacteria standards in the first AAMI hemodialysis guideline at

<2,000 CFU/mL in dialysate and one log lower (<200 CFU/mL) for the water used to prepare

dialysate.

668, 788

If the level of bacterial contamination exceeded 200 CFU/mL in water, this level could

be amplified in the system and effectively constitute a high inoculum for dialysate at the start of a

Potable water

Blending

valve

Multimedia/

sand/depth

filtration

Softener Carbon

adsorption

media (2 beds in

series

)

Particulate/

m filter

Reverse
osmosis

Storage tank and/or
optional additional
components:
deionization tanks
UV lamp
ultrafilters

Product
water

dialysis treatment.

807, 808

Pyrogenic reactions did not appear to occur when the level of contamination

was below 2,000 CFU/mL in dialysate unless the source of the endotoxin was exogenous to the dialysis

system (i.e., present in the community water supply). Endotoxins in a community water supply have

been linked to the development of pyrogenic reactions among dialysis patients.

794

Whether endotoxin actually crosses the dialyzer membrane is controversial. Several investigators have

shown that bacteria growing in dialysate-generated products that could cross the dialyzer membrane.

809,

810

Gram-negative bacteria growing in dialysate have produced endotoxins that in turn stimulated the

production of anti-endotoxin antibodies in hemodialysis patients;

801, 811

these data suggest that bacterial

endotoxins, although large molecules, cross dialyzer membranes either intact or as fragments. The use

of the very permeable membranes known as high-flux membranes (which allow large molecules [e.g.,

microglobulin] to traverse the membrane) increases the potential for passage of endotoxins into the

blood path. Several studies support this contention. In one such study, an increase in plasma endotoxin

concentrations during dialysis was observed when patients were dialyzed against dialysate containing

–10

CFU/mL

Pseudomonas

spp.

812

In vitro

studies using both radiolabeled lipopolysaccharide and

biologic assays have demonstrated that biologically active substances derived from bacteria found in

dialysate can cross a variety of dialyzer membranes.

802, 813–816

Patients treated with high-flux

membranes have had higher levels of anti-endotoxin antibodies than subjects or patients treated with

conventional membranes.

817

Finally, since 1989, 19%–22% of dialysis centers have reported pyrogenic

reactions in the absence of septicemia.

818, 819

Investigations of adverse outcomes among patients using reprocessed dialyzers have demonstrated a

greater risk for developing pyrogenic reactions when the water used to reprocess these devices

contained >6 ng/mL endotoxin and >10

CFU/mL bacteria.

820

In addition to the variability in

endotoxin assays, host factors also are involved in determining whether a patient will mount a response

to endotoxin.

803

Outbreak investigations of pyrogenic reactions and bacteremias associated with

hemodialyzer reuse have demonstrated that pyrogenic reactions are prevented once the endotoxin level

in the water used to reprocess the dialyzers is returned to below the AAMI standard level.

821

Reuse of dialyzers and use of bicarbonate dialysate, high-flux dialyzer membranes, or high-flux dialysis

may increase the potential for pyrogenic reactions if the water in the dialysis setting does not meet

standards.

796–798

Although investigators have been unable to demonstrate endotoxin transfer across

dialyzer membranes,

803, 822, 823

the preponderance of reports now supports the ability of endotoxin to

transfer across at least some high-flux membranes under some operating conditions. In addition to the

acute risk of pyrogenic reactions, indirect evidence in increasingly demonstrating that chronic exposure

to low amounts of endotoxin may play a role in some of the long-term complications of hemodialysis

therapy. Patients treated with ultrafiltered dialysate for 5–6 months have demonstrated a decrease in

serum

microglobulin concentrations and a decrease in markers of an inflammatory response.

824–826

studies of longer duration, use of microbiologically ultrapure dialysate has been associated with a

decreased incidence of

microglobulin-associated amyloidosis.

827, 828

Although patient benefit likely is associated with the use of ultrapure dialysate, no consensus has been

reached regarding the potential adoption of this as standard in the United States. Debate continues

regarding the bacterial and endotoxin limits for dialysate. As advances in water treatment and

hemodialysis processes occur, efforts are underway to move improved technology from the

manufacturer out into the user community. Cost-benefit studies, however, have not been done, and

substantially increased costs to implement newer water treatment modalities are anticipated.

To reconcile AAMI documents with current International Organization for Standardization (ISO)

format, AAMI has determined that its hemodialysis standards will be discussed in the following four

installments: RD 5 for hemodialysis equipment, RD 62 for product water quality, RD 47 for dialyzer

reprocessing, and RD 52 for dialysate quality. The Renal Diseases and Dialysis Committee of AAMI is

expected to finalize and promulgated the dialysate standard pertinent to the user community (RD 52),

adopting by reference the bacterial and endotoxin limits in product water as currently outlined in the

AAMI standard that applies to systems manufacturers (RD 62). At present, the user community should

continue to observe water quality and dialysate standards as outlined in AAMI RD 5 (Hemodialysis

Systems, 1992) and AAMI RD 47 (Reuse of Hemodialyzers, 1993) until the new RD 52 standard

becomes available (Table 18).

789, 791

Table 18. Microbiologic limits for hemodialysis fluids*

Hemodialysis fluid

Maximum total heterotrophs

(CFU/mL)+

Maximum endotoxin level

(EU/mL)§

Present standard

Product water¶

Used to prepare dialysate

Used to reprocess dialyzers

Dialysate

200

2,000

No standard

Proposed standard**

Product water

Dialysate

200

* The material in this table was compiled from references 789 and 791 (ANSI/AAMI standards RD 5-1992 and ANSI/AAMI RD 47-1993).

+ Colony forming units per milliliter.

§ Endotoxin units per milliliter.

¶ Product water presently includes water used to prepare dialysate and water used to reprocess dialyzers.

** Dialysate for hemodialysis, RD 52, under development, American National Standards Institute, Association for the Advancement of

Medical Instrumentation (AAMI).

The current AAMI standard directed at systems manufacturers (RD 62 [Water Treatment Equipment for

Hemodialysis Applications, 2001]) now specifies that all product water used to prepare dialysate or to

reprocess dialyzers for multiple use should contain <2 endotoxin units per milliliter (EU/mL).

792

level of 2 EU/mL was chosen as the upper limit for endotoxin because this level is easily achieved with

contemporary water treatment systems using RO and/or ultrafiltration. CDC has advocated monthly

endotoxin testing along with microbiologic assays of water, because endotoxin activity may not

correspond to the total heterotrophic plate counts.

829

Additionally, the current AAMI standard RD 62

for manufacturers includes action levels for product water. Because 48 hours can elapse between the

time of sampling water for microbial contamination and the time when results are received, and because

bacterial proliferation can be rapid, action levels for microbial counts and endotoxin concentrations are

reported as 50 CFU/mL and 1 EU/mL, respectively, in this revision of the standard.

792

These

recommendations will allow users to initiate corrective action before levels exceed the maximum levels

established by the standard.

In hemodialysis, the net movement of water is from the blood to the dialysate, although within the

dialyzer, local movement of water from the dialysate to the blood through the phenomenon of back-

filtration may occur, particularly in dialyzers with highly permeable membranes.

830

In contrast,

hemofiltration and hemodiaflltration feature infusion of large volumes of electrolyte solution (20–70 L)

into the blood. Increasingly, this electrolyte solution is being prepared on-line from water and

concentrate. Because of the large volumes of fluid infused, AAMI considered the necessity of setting

more stringent requirements for water to be used in this application, but this organization has not yet

established these because of lack of expert consensus and insufficient experience with on-line therapies

in the United States. On-line hemofiltration and hemodiafiltration systems use sequential ultrafiltration

as the final step in the preparation of infusion fluid. Several experts from AAMI concur that these

point-of-use ultrafiltration systems should be capable of further reducing the bacteria and endotoxin

burden of solutions prepared from water meeting the requirements of the AAMI standard to a safe level

for infusion.

b. Microbial Control Strategies

The strategy for controlling massive accumulations of gram-negative water bacteria and NTM in

dialysis systems primarily involves preventing their growth through proper disinfection of water-

treatment systems and hemodialysis machines. Gram-negative water bacteria, their associated

lipopolysaccharides (bacterial endotoxins), and NTM ultimately come from the community water

supply, and levels of these bacteria can be amplified depending on the water treatment system, dialysate

distribution system, type of dialysis machine, and method of disinfection (Table 19).

634, 794, 831

Control

strategies are designed to reduce levels of microbial contamination in water and dialysis fluid to

relatively low levels but not to completely eradicate it.

Table 19. Factors influencing microbial contamination in hemodialysis systems

Factors Comments

Water supply

Source of community water

Ground water

Surface water

Contains endotoxin and bacteria

Contains high levels of endotoxin and bacteria

Water treatment at the dialysis center

None

Filtration

Prefilter

Absolute filter (depth or membrane filter)

Activated carbon filter

Not recommended

Particulate filter to protect equipment; does not remove microorganisms

Removes bacteria, however, unless the filter is changed frequently or

disinfected, bacteria will accumulate and grow through the filter; acts

as a significant reservoir of bacteria and endotoxin

Removes organics and available chlorine or chloramines; acts as a

significant reservoir of bacteria and endotoxin

Water treatment devices

Deionization/ion-exchange softener

Reverse osmosis (RO)

Ultraviolet light

Ultrafilter

Both softeners and deionizers are significant reservoirs of bacteria and do

not remove endotoxin.

Removes bacteria and endotoxin, but must be disinfected; operates at high

water pressure

Kills some bacteria, but there is no residual; ultraviolet-resistant bacteria

can develop if the unit is not properly maintained

Removes bacteria and endotoxin; operates on normal line pressure; can be

positioned distal to deionizer; must be disinfected

Water and dialysate distribution system

Distribution pipes

Size

Construction

Elevation

Storage tanks

Oversized diameter and length decrease fluid flow and increase bacterial

reservoir for both treated water and centrally-prepared dialysate.

Rough joints, dead ends, unused branches, and polyvinyl chloride (PVC)

piping can act as bacterial reservoirs.

Outlet taps should be located at the highest elevation to prevent loss of

disinfectant; keep a recirculation loop in the system; flush unused ports

routinely.

Tanks are undesirable because they act as a reservoir for water bacteria; if

tanks are present, they must be routinely scrubbed and disinfected.

Dialysis machines

Single-pass

Recirculating single-pass or recirculating

(batch)

Disinfectant should have contact with

all

parts of the machine that are

exposed to water or dialysis fluid.

Recirculating pumps and machine design allow for massive contamination

levels if not properly disinfected; overnight chemical germicide

treatment is recommended.

Two components of hemodialysis water distribution systems – pipes (particularly those made of

polyvinyl chloride [PVC]) and storage tanks – can serve as reservoirs of microbial contamination.

Hemodialysis systems frequently use pipes that are wider and longer than are needed to handle the

required flow, which slows the fluid velocity and increases both the total fluid volume and the wetted

surface area of the system. Gram-negative bacteria in fluids remaining in pipes overnight multiply

rapidly and colonize the wet surfaces, producing bacterial populations and endotoxin quantities in

proportion to the volume and surface area. Such colonization results in formation of protective biofilm

that is difficult to remove and protects the bacteria from disinfection.

832

Routine (i.e., monthly), low-

level disinfection of the pipes can help to control bacterial contamination of the distribution system.

Additional measures to protect pipes from contaminations include a) situating all outlet taps at equal

elevation and at the highest point of the system so that the disinfectant cannot drain from pipes by

gravity before adequate contact time has elapsed and b) eliminating rough joints, dead-end pipes, and

unused branches and taps that can trap fluid and serve as reservoirs of bacteria capable of continuously

inoculating the entire volume of the system.

800

Maintain a flow velocity of 3–5 ft/sec.

A storage tank in the distribution system greatly increases the volume of fluid and surface area available

and can serve as a niche for water bacteria. Storage tanks are therefore not recommended for use in

dialysis systems unless they are frequently drained and adequately disinfected, including scrubbing the

sides of the tank to remove bacterial biofilm. An ultrafilter should be used distal to the storage tank.

808,

833

Microbiologic sampling of dialysis fluids is recommended because gram-negative bacteria can

proliferate rapidly in water and dialysate in hemodialysis systems; high levels of these organisms place

patients at risk for pyrogenic reactions or health-care–associated infection.

667, 668, 808

Health-care facilities are advised to sample dialysis fluids at least monthly using standard microbiologic

assay methods for waterborne microorganisms.

788, 793, 799, 834–836

Product water used to prepare dialysate

and to reprocess hemodialyzers for reuse on the same patient should also be tested for bacterial

endotoxin on a monthly basis.

792, 829, 837

(See Appendix C for information about water sampling

methods for dialysis.)

Cross-contamination of dialysis machines and inadequate disinfection measures can facilitate the spread

of waterborne organisms to patients. Steps should be taken to ensure that dialysis equipment is

performing correctly and that all connectors, lines, and other components are specific for the equipment,

in good repair, and properly in place. A recent outbreak of gram-negative bacteremias among dialysis

patients was attributed to faulty valves in a drain port of the machine that allowed backflow of saline

used to flush the dialyzer before patient use.

838, 839

This backflow contaminated the drain priming

connectors, which contaminated the blood lines and exposed the patients to high concentrations of

gram-negative bacteria. Environmental infection control in dialysis settings also includes low-level

disinfection of housekeeping surfaces and spot decontamination of spills of blood (see Environmental

Services in Part I of this guideline for further information).

c. Infection-Control Issues in Peritoneal Dialysis

Peritoneal dialysis (PD), most commonly administered as continuous ambulatory peritoneal dialysis

(CAPD) and continual cycling peritoneal dialysis (CCPD), is the third most common treatment for end-

stage renal disease (ESRD) in the United States, accounting for 12% of all dialysis patients.

840

Peritonitis is the primary complication of CAPD, with coagulase-negative staphylococci the most

clinically significant causative organisms.

841

Other organisms that have been found to produce

peritonitis include

Staphylococcus aureus, Mycobacterium fortuitum, M. mucogenicum,

Stenotrophomonas maltophilia, Burkholderia cepacia, Corynebacterium jeikeium, Candida

spp., and

other fungi.

842–850

Substantial morbidity is associated with peritoneal dialysis infections. Removal of

peritoneal dialysis catheters usually is required for treatment of peritonitis caused by fungi, NTM, or

other bacteria that are not cleared within the first several days of effective antimicrobial treatment.

Furthermore, recurrent episodes of peritonitis may lead to fibrosis and loss of the dialysis membrane.

Many reported episodes of peritonitis are associated with exit-site or tunneled catheter infections. Risk

factors for the development of peritonitis in PD patients include a) under dialysis, b) immune

suppression, c) prolonged antimicrobial treatment, d) patient age [more infections occur in younger

patients and older hospitalized patients], e) length of hospital stay, and f) hypoalbuminemia.

844, 851, 852

Concern has been raised about infection risk associated with the use of automated cyclers in both

inpatient and outpatient settings; however, studies suggest that PD patients who use automated cyclers

have much lower infection rates.

853

One study noted that a closed-drainage system reduced the

incidence of system-related peritonitis among intermittent peritoneal dialysis (IPD) patients from 3.6 to

1.5 cases/100 patient days.

854

The association of peritonitis with management of spent dialysate fluids

requires additional study. Therefore, ensuring that the tip of the waste line is not submerged beneath the

water level in a toilet or in a drain is prudent.

7. Ice Machines and Ice

Microorganisms may be present in ice, ice-storage chests, and ice-making machines. The two main

sources of microorganisms in ice are the potable water from which it is made and a transferral of

organisms from hands (Table 20). Ice from contaminated ice machines has been associated with patient

colonization, blood stream infections, pulmonary and gastrointestinal illnesses, and pseudoinfections.

602,

603, 683, 684, 854, 855

Microorganisms in ice can secondarily contaminate clinical specimens and medical

solutions that require cold temperatures for either transport or holding.

601, 620

An outbreak of surgical-

site infections was interrupted when sterile ice was used in place of tap water ice to cool cardioplegia

solutions.

601

Table 20. Microorganisms and their sources in ice and ice machines

Sources of microorganisms

References

From potable water

Legionella

spp.

684, 685, 857, 858

Nontuberculous mycobacteria (NTM)

602, 603, 859

Pseudomonas aeruginosa

859

Burkholderia cepacia

859,

860

Stenotrophomonas maltophilia

860

Flavobacterium

spp.

860

From fecally-contaminated water

Norwalk

virus

861–863

Giardia lamblia

864

Cryptosporidium parvum

685

From hand-transfer of organisms

Acinetobacter

spp.

859

Coagulase-negative

staphylococci

859

Salmonella enteriditis

865

Cryptosporidium parvum

685

In a study comparing the microbial populations of hospital ice machines with organisms recovered from

ice samples gathered from the community, samples from 27 hospital ice machines yielded low numbers

(<10 CFU/mL) of several potentially opportunistic microorganisms, mainly gram-negative bacilli.

859

During the survey period, no health-care–associated infections were attributed to the use of ice. Ice

from community sources had higher levels of microbial contamination (75%–95% of 194 samples had

total heterotrophic plate counts <500 CFU/mL, with the proportion of positive cultures dependent on the

incubation temperature) and showed evidence of fecal contamination from the source water.

859

Thus,

ice machines in health-care settings are no more heavily contaminated compared with ice machines in

the community. If the source water for ice in a health-care facility is not fecally contaminated, then ice

from clean ice machines and chests should pose no increased hazard for immunocompetent patients.

Some waterborne bacteria found in ice could potentially be a risk to immunocompromised patients if

they consume ice or drink beverages with ice. For example,

Burkholderia cepacia

in ice could present

an infection risk for cystic fibrosis patients.

859, 860

Therefore, protecting immunosuppressed and

otherwise medically at-risk patients from exposure to tap water and ice potentially contaminated with

opportunistic pathogens is prudent.

No microbiologic standards for ice, ice-making machines, or ice storage equipment have been

established, although several investigators have suggested the need for such standards.

859, 866

Culturing

of ice machines is not routinely recommended, but it may be useful as part of an epidemiologic

investigation.

867–869

Sampling might also help determine the best schedule for cleaning open ice-storage

chests. Recommendations for a regular program of maintenance and disinfection have been

published.

866–869

Health-care facilities are advised to clean ice-storage chests on a regular basis. Open

ice chests may require a more frequent cleaning schedule compared with chests that have covers.

Portable ice chests and containers require cleaning and low-level disinfection before the addition of ice

intended for consumption. Ice-making machines may require less frequent cleaning, but their

maintenance is important to proper performance. The manufacturer’s instructions for both the proper

method of cleaning and/or maintenance should be followed. These instructions may also recommend an

EPA-registered disinfectant to ensure chemical potency, materials compatibility, and safety. In the

event that instructions and suitable EPA-registered disinfectants are not available for this process, then a

generic approach to cleaning, disinfecting, and maintaining ice machines and dispensers can be used

(Box 12).

Ice and ice-making machines also may be contaminated via improper storage or handling of ice by

patients and/or staff.

684–686, 855–858, 870

Suggested steps to avoid this means of contamination include a)

minimizing or avoiding direct hand contact with ice intended for consumption, b) using a hard-surface

scoop to dispense ice, and c) installing machines that dispense ice directly into portable containers at the

touch of a control.

687, 869

Box 12. General steps for cleaning and maintaining ice machines, dispensers, and storage
chests*+

1. Disconnect unit from power supply.

2. Remove and discard ice from bin or storage chest.

3. Allow unit to warm to room temperature.

4. Disassemble removable parts of machine that make contact with water to make ice.

5. Thoroughly clean machine and parts with water and detergent.

6. Dry external surfaces of removable parts before reassembling.

7. Check for any needed repair.

8. Replace feeder lines, as appropriate (e.g., when damaged, old, or difficult to clean).

9. Ensure presence of an air space in tubing leading from water inlet into water distribution system of

machine.

(Box 12. continued)

10. Inspect for rodent or insect infestations under the unit and treat, as needed.

11. Check door gaskets (open compartment models) for evidence of leakage or dripping into the

storage chest.

12. Clean the ice-storage chest or bin with fresh water and detergent; rinse with fresh tap water.

13. Sanitize machine by circulating a 50–100 parts per million (ppm) solution of sodium hypochlorite

(i.e., 4–8 mL sodium hypochlorite/gallon of water) through the ice-making and storage systems for
2 hours (100 ppm solution), or 4 hours (50 ppm solution).

14. Drain sodium hypochlorite solutions and flush with fresh tap water.

15. Allow all surfaces of equipment to dry before returning to service.

* Material in this box is adapted from reference 869.

+ These general guidelines should be used only where manufacturer-recommended methods and EPA-registered disinfectants are not

available.

8. Hydrotherapy Tanks and Pools

a. General Information

Hydrotherapy equipment (e.g., pools, whirlpools, whirlpool spas, hot tubs, and physiotherapy tanks)

traditionally has been used to treat patients with certain medical conditions (e.g., burns,

871, 872

septic

ulcers, lesions, amputations,

873

orthopedic impairments and injuries, arthritis,

874

and kidney

lithotripsy).

654

Wound-care medicine is increasingly moving away from hydrotherapy, however, in

favor of bedside pulsed-lavage therapy using sterile solutions for cleaning and irrigation.

492, 875–878

Several episodes of health-care–associated infections have been linked to use of hydrotherapy

equipment (Table 21). Potential routes of infection include incidental ingestion of the water, sprays and

aerosols, and direct contact with wounds and intact skin (folliculitis). Risk factors for infection include

a) age and sex of the patient, b) underlying medical conditions, c) length of time spent in the

hydrotherapy water, and d) portals of entry.

879

Table 21. Infections associated with use of hydrotherapy equipment

Microorganisms Medical

conditions

References

Acinetobacter baumanii

Sepsis 572

Citrobacter freundii

Cellulitis 880

Enterobacter cloacae

Sepsis 881

Legionella

spp.

Legionellosis

882

Mycobacterium abscessus, Mycobacterium
fortuitum, Mycobacterium marinum

Skin ulcers and soft tissue infections

621–623, 883

Pseudomonas aeruginosa

Sepsis, soft tissue infections, folliculitis, and

wound infections

492, 493, 506, 679, 884–888

Adenovirus, adeno-associated virus

Conjunctivitis

889

Infection control for hydrotherapy tanks, pools, or birthing tanks presents unique challenges because

indigenous microorganisms are always present in the water during treatments. In addition, some studies

have found free living amoebae (i.e.,

Naegleria lovaniensis

), which are commonly found in association

with

Naegleria fowleri,

in hospital hydrotherapy pools.

890

Although hydrotherapy is at times

appropriate for patients with wounds, burns, or other types of non-intact skin conditions (determined on

a case-by-case basis), this equipment should not be considered “semi-critical” in accordance with the

Spaulding classification.

891

Microbial data to evaluate the risk of infection to patients using

hydrotherapy pools and birthing tanks are insufficient. Nevertheless, health-care facilities should

maintain stringent cleaning and disinfection practices in accordance with the manufacturer’s instructions

and with relevant scientific literature until data supporting more rigorous infection-control measures

become available. Factors that should be considered in therapy decisions in this situation would include

a) availability of alternative aseptic techniques for wound management and b) a risk-benefit analysis of

using traditional hydrotherapy.

b. Hydrotherapy Tanks

Hydrotherapy tanks (e.g., whirlpools, Hubbard tanks and whirlpool bath tubs) are shallow tanks

constructed of stainless steel, plexiglass, or tile. They are closed-cycle water systems with hydrojets to

circulate, aerate, and agitate the water. The maximum water temperature range is 50°F–104°F (10°C–

40°C). The warm water temperature, constant agitation and aeration, and design of the hydrotherapy

tanks provide ideal conditions for bacterial proliferation if the equipment is not properly maintained,

cleaned, and disinfected. The design of the hydrotherapy equipment should be evaluated for potential

infection-control problems that can be associated with inaccessible surfaces that can be difficult to clean

and/or remain wet in between uses (i.e., recessed drain plates with fixed grill plates).

887

Associated

equipment (e.g., parallel bars, plinths, Hoyer lifts, and wheelchairs) can also be potential reservoirs of

microorganisms, depending on the materials used in these items (i.e., porous vs. non-porous materials)

and the surfaces that may become wet during use. Patients with active skin colonizations and wound

infections can serve as sources of contamination for the equipment and the water. Contamination from

spilled tub water can extend to drains, floors, and walls.

680–683

Health-care–associated colonization or

infection can result from exposure to endogenous sources of microorganisms (autoinoculation) or

exogenous sources (via cross-contamination from other patients previously receiving treatment in the

unit).

Although some facilities have used tub liners to minimize environmental contamination of the tanks, the

use of a tub liner does not eliminate the need for cleaning and disinfection. Draining these small pools

and tanks after each patient use, thoroughly cleaning with a detergent, and disinfecting according to

manufacturers’ instructions have reduced bacterial contamination levels in the water from 10

CFU/mL

to <10 CFU/mL.

892

A chlorine residual of 15 ppm in the water should be obtained prior to the patient’s

therapy session (e.g., by adding 15 grams of calcium hypochlorite 70% [e.g., HTH®] per 100 gallons of

water).

892

A study of commercial and residential whirlpools found that superchlorination or draining,

cleaning, disinfection, and refilling of whirlpools markedly reduced densities of

Pseudomonas

aeruginosa

in whirlpool water.

893

The bacterial populations were rapidly replenished, however, when

disinfectant concentrations dropped below recommended levels for recreational use (i.e., chlorine at 3.0

ppm or bromine at 6.0 ppm). When using chlorine, however, knowing whether the community

drinking-water system is disinfected with chloramine is important, because municipal utilities adjust the

pH of the water to the basic side to enhance chloramine formation. Because chlorine is not very

effective at pH levels above 8, it may be necessary to re-adjust the pH of the water to a more acidic

level.

894

A few reports describe the addition of antiseptic chemicals to hydrotherapy tank water, especially for

burn patient therapy.

895–897

One study involving a minimal number of participants demonstrated a

reduction in the number of

Pseudomonas

spp. and other gram-negative bacteria from both patients and

equipment surfaces when chloramine-T (“chlorazene”) was added to the water.

898

Chloramine-T has

not, however, been approved for water treatment in the United States.

c. Hydrotherapy Pools

Hydrotherapy pools typically serve large numbers of patients and are usually heated to 91.4°F–98.6°F

(31°C–37°C). The temperature range is more narrow (94°F–96.8°F [35°C–36°C]) for pediatric and

geriatric patient use.

899

Because the size of hydrotherapy pools precludes draining after patient use,

proper management is required to maintain the proper balance of water conditioning (i.e., alkalinity,

hardness, and temperature) and disinfection. The most widely used chemicals for disinfection of pools

are chlorine and chlorine compounds – calcium hypochlorite, sodium hypochlorite, lithium

hypochlorite, chloroisocyanurates, and chlorine gas. Solid and liquid formulations of chlorine

chemicals are the easiest and safest to use.

900

Other halogenated compounds have also been used for

pool-water disinfection, albeit on a limited scale. Bromine, which forms bactericidal bromamines in the

presence of ammonia, has limited use because of its association with contact dermatitis.

901

Iodine does

not bleach hair, swim suits, or cause eye irritation, but when introduced at proper concentrations, it

gives water a greenish-yellowish cast.

892

In practical terms, maintenance of large hydrotherapy pools (e.g., those used for exercise) is similar to

that for indoor public pools (i.e., continuous filtration, chlorine residuals no less than 0.4 ppm, and pH

of 7.2–7.6).

902, 903

Supply pipes and pumps also need to be maintained to eliminate the possibility of

this equipment serving as a reservoir for waterborne organisms.

904

Specific standards for chlorine

residual and pH of the water are addressed in local and state regulations. Patients who are fecally

incontinent or who have draining wounds should refrain from using these pools until their condition

improves.

d. Birthing Tanks and Other Equipment

The use of birthing tanks, whirlpool spas, and whirlpools is a recent addition to obstetrical practice.

905

Few studies on the potential risks associated with these pieces of equipment have been conducted. In

one study of 32 women, a newborn contracted a

Pseudomonas

infection after being birthed in such a

tank, the strain of which was identical to the organism isolated from the tank water.

906

Another report

documented identical strains of

P. aeruginosa

isolates from a newborn with sepsis and on the

environmental surfaces of a tub that the mother used for relaxation while in labor.

907

Other studies have

shown no significant increases in the rates of post-immersion infections among mothers and infants.

908,

909

Because the water and the tub surfaces routinely become contaminated with the mother’s skin flora and

blood during labor and delivery, birthing tanks and other tub equipment must be drained after each

patient use and the surfaces thoroughly cleaned and disinfected. Health-care facilities are advised to

follow the manufacturer’s instructions for selection of disinfection method and chemical germicide.

The range of chlorine residuals for public whirlpools and whirlpool spas is 2–5 ppm.

910

Use of an

inflatable tub is an alternative solution, but this item must be cleaned and disinfected between patients if

it is not considered a single-use unit.

Recreational tanks and whirlpool spas are increasingly being used as hydrotherapy equipment.

Although such home equipment appears to be suitable for hydrotherapy, they are neither designed nor

constructed to function in this capacity. Additionally, manufacturers generally are not obligated to

provide the health-care facility with cleaning and disinfecting instructions appropriate for medical

equipment use, and the U.S. Food and Drug Administration (FDA) does not evaluate recreational

equipment. Health-care facilities should therefore carefully evaluate this “off-label” use of home

equipment before proceeding with a purchase.

9. Miscellaneous Medical/Dental Equipment Connected to Main Water
Systems

a. Automated Endoscope Reprocessors

The automated endoscopic reprocessor (AER) is classified by the FDA as an accessory for the flexible

endoscope.

654

A properly operating AER can provide a more consistent, reliable method of

decontaminating and terminal reprocessing for endoscopes between patient procedures than manual

reprocessing methods alone.

911

An endoscope is generally subjected to high-level disinfection using a

liquid chemical sterilant or a high-level disinfectant. Because the instrument is a semi-critical device,

the optimal rinse fluid for a disinfected endoscope would be sterile water.

Sterile water, however, is

expensive and difficult to produce in sufficient quantities and with adequate quality assurance for

instrument rinsing in an AER.

912, 913

Therefore, one option to be used for AERs is rinse water that has

been passed through filters with a pore size of 0.1–0.2 µm to render the water “bacteria-free.” These

filters usually are located in the water line at or near the port where the mains water enters the

equipment. The product water (i.e., tap water passing through these filters) in these applications is not

considered equivalent in microbial quality to that for membrane-filtered water as produced by

pharmaceutical firms. Membrane filtration in pharmaceutical applications is intended to ensure the

microbial quality of polished product water.

Water has been linked to the contamination of flexible fiberoptic endoscopes in the following two

scenarios: a) rinsing a disinfected endoscope with unfiltered tap water, followed by storage of the

instrument without drying out the internal channels and b) contamination of AERs from tap water

inadvertently introduced into the equipment. In the latter instance, the machine’s water reservoirs and

fluid circuitry become contaminated with waterborne, heterotrophic bacteria (e.g.,

Pseudomonas

aeruginosa

and NTM), which can survive and persist in biofilms attached to these components.

914–917

Colonization of the reservoirs and water lines of the AER becomes problematic if the required cleaning,

disinfection, and maintenance are not performed on the equipment as recommended by the

manufacturer.

669, 916, 917

Use of the 0.1–0.2-µm filter in the water line helps to keep bacterial

contamination to a minimum,

670, 911, 917

but filters may fail and allow bacteria to pass through to the

equipment and then to the instrument undergoing reprocessing.

671–674, 913, 918

Filters also require

maintenance for proper performance.

670, 911, 912, 918, 919

Heightened awareness of the proper disinfection

of the connectors that hook the instrument to the AER may help to further reduce the potential for

contaminating endoscopes during reprocessing.

920

An emerging issue in the field of endoscopy is that

of the possible role of rinse water monitoring and its potential to help reduce endoscopy/bronchoscopy-

associated infections.

918

Studies have linked deficiencies in endoscope cleaning and/or disinfecting processes to the incidence of

post-endoscopic adverse outcomes.

921–924

Several clusters have been traced to AERs of older designs

and these were associated with water quality.

675, 914–916

Regardless of whether manual or automated

terminal reprocessing is used for endoscopes, the internal channels of the instrument should be dried

before storage.

925

The presence of residual moisture in the internal channels encourages the

proliferation of waterborne microorganisms, some of which may be pathogenic. One of the most

frequently used methods employs 70% isopropyl alcohol to flush the internal channels, followed by

forced air drying of these channels and hanging the endoscope vertically in a protected cabinet; this

method ensures internal drying of the endoscope, lessens the potential for proliferation of waterborne

microorganisms,

669, 913, 917, 922, 926, 927

and is consistent with professional organization guidance for

endoscope reprocessing.

928

An additional problem with waterborne microbial contamination of AERs centers on increased

microbial resistance to alkaline glutaraldehyde, a widely used liquid chemical sterilant/high-level

disinfectant.

669, 929

Opportunistic waterborne microorganisms (e.g.,

Mycobacterium chelonae

Methylobacterium

spp.) have been associated with pseudo-outbreaks and colonization; infection caused

by these organisms has been associated with procedures conducted in clinical settings (e.g.,

bronchoscopy).

669, 913, 929–931

Increasing microbial resistance to glutaraldehyde has been attributed to

improper use of the disinfectant in the equipment, allowing the dilution of glutaraldehyde to fall below

the manufacturer’s recommended minimal use concentration.

929

b. Dental Unit Water Lines

Dental unit water lines (DUWLs) consist of small-bore plastic tubing that delivers water used for

general, non-surgical irrigation and as a coolant to dental handpieces, sonic and ultrasonic scalers, and

air-water syringes; municipal tap water is the source water for these lines. The presence of biofilms of

waterborne bacteria and fungi (e.g.,

Legionella

spp.,

Pseudomonas aeruginosa,

and NTM) in DUWLs

has been established.

636, 637, 694, 695, 932– 934

Biofilms continually release planktonic microorganisms into

the water, the titers of which can exceed 1

CFU/mL.

694

However, scientific evidence indicates that

immunocompetent persons are only at minimal risk for substantial adverse health effects after contact

with water from a dental unit. Nonetheless, exposing patients or dental personnel to water of uncertain

microbiological quality is not consistent with universally accepted infection-control principles.

935

In 1993, CDC issued guidelines relative to water quality in a dental setting. These guidelines

recommend that all dental instruments that use water (including high-speed handpieces) should be run to

discharge water for 20–30 seconds after each patient and for several minutes before the start of each

clinic day.

936

This practice can help to flush out any patient materials that many have entered the

turbine, air, or waterlines.

937, 938

The 1993 guidance also indicated that waterlines be flushed at the

beginning of the clinic day. Although these guidelines are designed to help reduce the number of

microorganisms present in treatment water, they do not address the issue of reducing or preventing

biofilm formation in the waterlines. Research published subsequent to the 1993 dental infection control

guideline suggests that flushing the lines at the beginning of the day has only minimal effect on the

status of the biofilm in the lines and does not reliably improve the quality of water during dental

treatment.

939–941

Updated recommendations on infection-control practices for water line use in dentistry

will be available in late 2003.

942

The numbers of microorganisms in water used as coolant or irrigant for non-surgical dental treatment

should be as low as reasonably achievable and, at a minimum, should meet nationally recognized

standards for safe drinking water.

935, 943

Only minimal evidence suggests that water meeting drinking

water standards poses a health hazard for immunocompetent persons. The EPA, the American Public

Health Association (APHA), and the American Water Works Association (AWWA) have set a

maximum limit of 500 CFU/mL for aerobic, heterotrophic, mesophilic bacteria in drinking water in

municipal distribution systems.

944, 945

This standard is achievable, given improvements in water-line

technology. Dentists should consult with the manufacturer of their dental unit to determine the best

equipment and method for maintaining and monitoring good water quality.

935, 946

E. Environmental Services

1. Principles of Cleaning and Disinfecting Environmental Surfaces

Although microbiologically contaminated surfaces can serve as reservoirs of potential pathogens, these

surfaces generally are not directly associated with transmission of infections to either staff or patients.

The transferral of microorganisms from environmental surfaces to patients is largely via hand contact

with the surface.

947, 948

Although hand hygiene is important to minimize the impact of this transfer,

cleaning and disinfecting environmental surfaces as appropriate is fundamental in reducing their

potential contribution to the incidence of healthcare-associated infections.

The principles of cleaning and disinfecting environmental surfaces take into account the intended use of

the surface or item in patient care. CDC retains the Spaulding classification for medical and surgical

instruments, which outlines three categories based on the potential for the instrument to transmit

infection if the instrument is microbiologically contaminated before use.

949, 950

These categories are

“critical,” “semicritical,” and “noncritical.” In 1991, CDC proposed an additional category designated

“environmental surfaces” to Spaulding’s original classification

951

to represent surfaces that generally do

not come into direct contact with patients during care. Environmental surfaces carry the least risk of

disease transmission and can be safely decontaminated using less rigorous methods than those used on

medical instruments and devices. Environmental surfaces can be further divided into medical

equipment surfaces (e.g., knobs or handles on hemodialysis machines, x-ray machines, instrument carts,

and dental units) and housekeeping surfaces (e.g., floors, walls, and tabletops).

951

The following factors influence the choice of disinfection procedure for environmental surfaces: a) the

nature of the item to be disinfected, b) the number of microorganisms present, c) the innate resistance of

those microorganisms to the inactivating effects of the germicide, d) the amount of organic soil present,

e) the type and concentration of germicide used, f) duration and temperature of germicide contact, and

g) if using a proprietary product, other specific indications and directions for use.

952, 953

Cleaning is the necessary first step of any sterilization or disinfection process. Cleaning is a form of

decontamination that renders the environmental surface safe to handle or use by removing organic

matter, salts, and visible soils, all of which interfere with microbial inactivation.

954–960

The physical

action of scrubbing with detergents and surfactants and rinsing with water removes large numbers of

microorganisms from surfaces.

957

If the surface is not cleaned before the terminal reprocessing

procedures are started, the success of the sterilization or disinfection process is compromised.

Spaulding proposed three levels of disinfection for the treatment of devices and surfaces that do not

require sterility for safe use. These disinfection levels are “high-level,” “intermediate-level,” and “low-

level.”

949, 950

The basis for these levels is that microorganisms can usually be grouped according to their

innate resistance to a spectrum of physical or chemical germicidal agents (Table 22). This information,

coupled with the instrument/surface classification, determines the appropriate level of terminal

disinfection for an instrument or surface.

Table 22. Levels of disinfection by type of microorganism*

Bacteria

Fungi+

Viruses

Disinfection

level

Vegetative

Tubercle

bacillus

Spores

Lipid and

medium size

Nonlipid and

small size

High

Intermediate

–

Low

– – +

* Material in this table compiled from references 2 and 951.

+ This class of microorganisms includes asexual spores but not necessarily chlamydospores or sexual spores.

§ The “plus” sign indicates that a killing effect can be expected when the normal use-concentrations of chemical disinfectants or pasteurization

are properly employed; a “negative” sign indicates little or no killing effect.

¶ Only with extended exposure times are high-level disinfectant chemicals capable of killing high numbers of bacterial spores in laboratory

tests; they are, however, capable of sporicidal activity.

** Some intermediate-level disinfectants (e.g., hypochlorites) can exhibit some sporicidal activity; others (e.g., alcohols and phenolics) have

no demonstrable sporicidal activity.

++ Some intermediate-level disinfectants, although they are tuberculocidal, may have limited virucidal activity.

The process of high-level disinfection, an appropriate standard of treatment for heat-sensitive, semi-

critical medical instruments (e.g., flexible, fiberoptic endoscopes), inactivates all vegetative bacteria,

mycobacteria, viruses, fungi, and some bacterial spores. High-level disinfection is accomplished with

powerful, sporicidal chemicals (e.g., glutaraldehyde, peracetic acid, and hydrogen peroxide) that are not

appropriate for use on housekeeping surfaces. These liquid chemical sterilants/high-level disinfectants

are highly toxic.

961–963

Use of these chemicals for applications other than those indicated in their label

instructions (i.e., as immersion chemicals for treating heat-sensitive medical instruments) is not

appropriate.

964

Intermediate-level disinfection does not necessarily kill bacterial spores, but it does

inactivate

Mycobacterium tuberculosis

var.

bovis

, which is substantially more resistant to chemical

germicides than ordinary vegetative bacteria, fungi, and medium to small viruses (with or without lipid

envelopes). Chemical germicides with sufficient potency to achieve intermediate-level disinfection

include chlorine-containing compounds (e.g., sodium hypochlorite), alcohols, some phenolics, and some

iodophors. Low-level disinfection inactivates vegetative bacteria, fungi, enveloped viruses (e.g., human

immunodeficiency virus [HIV], and influenza viruses), and some non-enveloped viruses (e.g.,

adenoviruses). Low-level disinfectants include quaternary ammonium compounds, some phenolics, and

some iodophors. Sanitizers are agents that reduce the numbers of bacterial contaminants to safe levels

as judged by public health requirements, and are used in cleaning operations, particularly in food service

and dairy applications. Germicidal chemicals that have been approved by FDA as skin antiseptics are

not appropriate for use as environmental surface disinfectants.

951

The selection and use of chemical germicides are largely matters of judgment, guided by product label

instructions, information, and regulations. Liquid sterilant chemicals and high-level disinfectants

intended for use on critical and semi-critical medical/dental devices and instruments are regulated

exclusively by the FDA as a result of recent memoranda of understanding between FDA and the EPA

that delineates agency authority for chemical germicide regulation.

965, 966

Environmental surface

germicides (i.e., primarily intermediate- and low-level disinfectants) are regulated by the EPA and

labeled with EPA registration numbers. The labels and technical data or product literature of these

germicides specify indications for product use and provide claims for the range of antimicrobial activity.

The EPA requires certain pre-registration laboratory potency tests for these products to support product

label claims. EPA verifies (through laboratory testing) manufacturers’ claims to inactivate

microorganisms for selected products and organisms. Germicides labeled as “hospital disinfectant”

have passed the potency tests for activity against three representative microorganisms –

Pseudomonas

aeruginosa, Staphylococcus aureus,

and

Salmonella cholerae suis

. Low-level disinfectants are often

labeled “hospital disinfectant” without a tuberculocidal claim, because they lack the potency to

inactivate mycobacteria. Hospital disinfectants with demonstrated potency against mycobacteria (i.e.,

intermediate-level disinfectants) may list “tuberculocidal” on the label as well. Other claims (e.g.,

“fungicidal,” “pseudomonicidal,” and “virucidal”) may appear on labels of environmental surface

germicides, but the designations of “tuberculocidal hospital disinfectant” and “hospital disinfectant”

correlate directly to Spaulding’s assessment of intermediate-level disinfectants and low-level

disinfectants, respectively.

951

A common misconception in the use of surface disinfectants in health-care settings relates to the

underlying purpose for use of proprietary products labeled as a “tuberculocidal” germicide. Such

products will not interrupt and prevent the transmission of TB in health-care settings because TB is not

acquired from environmental surfaces. The tuberculocidal claim is used as a benchmark by which to

measure germicidal potency. Because mycobacteria have the highest intrinsic level of resistance among

the vegetative bacteria, viruses, and fungi, any germicide with a tuberculocidal claim on the label (i.e.,

an intermediate-level disinfectant) is considered capable of inactivating a broad spectrum of pathogens,

including much less resistant organisms such the bloodborne pathogens (e.g., hepatitis B virus [HBV],

hepatitis C virus [HCV], and HIV). It is this broad spectrum capability, rather than the product’s

specific potency against mycobacteria, that is the basis for protocols and OSHA regulations indicating

the appropriateness of using tuberculocidal chemicals for surface disinfection.

967

2. General Cleaning Strategies for Patient-Care Areas

The number and types of microorganisms present on environmental surfaces are influenced by the

following factors: a) number of people in the environment, b) amount of activity, c) amount of moisture,

d) presence of material capable of supporting microbial growth, e) rate at which organisms suspended in

the air are removed, and f) type of surface and orientation [i.e., horizontal or vertical].

968

Strategies for

cleaning and disinfecting surfaces in patient-care areas take into account a) potential for direct patient

contact, b) degree and frequency of hand contact, and c) potential contamination of the surface with

body substances or environmental sources of microorganisms (e.g., soil, dust, and water).

a. Cleaning of Medical Equipment

Manufacturers of medical equipment should provide care and maintenance instructions specific to their

equipment. These instructions should include information about a) the equipments’ compatibility with

chemical germicides, b) whether the equipment is water-resistant or can be safely immersed for

cleaning, and c) how the equipment should be decontaminated if servicing is required.

967

In the

absence of manufacturers’ instructions, non-critical medical equipment (e.g., stethoscopes, blood

pressure cuffs, dialysis machines, and equipment knobs and controls) usually only require cleansing

followed by low- to intermediate-level disinfection, depending on the nature and degree of

contamination. Ethyl alcohol or isopropyl alcohol in concentrations of 60%–90% (v/v) is often used to

disinfect small surfaces (e.g., rubber stoppers of multiple-dose medication vials, and thermometers)

952,

969

and occasionally external surfaces of equipment (e.g., stethoscopes and ventilators). However,

alcohol evaporates rapidly, which makes extended contact times difficult to achieve unless items are

immersed, a factor that precludes its practical use as a large-surface disinfectant.

951

Alcohol may cause

discoloration, swelling, hardening, and cracking of rubber and certain plastics after prolonged and

repeated use and may damage the shellac mounting of lenses in medical equipment.

970

Barrier protection of surfaces and equipment is useful, especially if these surfaces are a) touched

frequently by gloved hands during the delivery of patient care, b) likely to become contaminated with

body substances, or c) difficult to clean. Impervious-backed paper, aluminum foil, and plastic or fluid-

resistant covers are suitable for use as barrier protection. An example of this approach is the use of

plastic wrapping to cover the handle of the operatory light in dental-care settings.

936, 942

Coverings

should be removed and discarded while the health-care worker is still gloved.

936, 942

The health-care

worker, after ungloving and performing hand hygiene, must cover these surfaces with clean materials

before the next patient encounter.

b. Cleaning Housekeeping Surfaces

Housekeeping surfaces require regular cleaning and removal of soil and dust. Dry conditions favor the

persistence of gram-positive cocci (e.g., coagulase-negative

Staphylococcus

spp.) in dust and on

surfaces, whereas moist, soiled environments favor the growth and persistence of gram-negative

bacilli.

948, 971, 972

Fungi are also present on dust and proliferate in moist, fibrous material.

Most, if not all, housekeeping surfaces need to be cleaned only with soap and water or a

detergent/disinfectant, depending on the nature of the surface and the type and degree of contamination.

Cleaning and disinfection schedules and methods vary according to the area of the health-care facility,

type of surface to be cleaned, and the amount and type of soil present. Disinfectant/detergent

formulations registered by EPA are used for environmental surface cleaning, but the actual physical

removal of microorganisms and soil by wiping or scrubbing is probably as important, if not more so,

than any antimicrobial effect of the cleaning agent used.

973

Therefore, cost, safety, product-surface

compatibility, and acceptability by housekeepers can be the main criteria for selecting a registered

agent. If using a proprietary detergent/disinfectant, the manufacturers’ instructions for appropriate use

of the product should be followed.

974

Consult the products’ material safety data sheets (MSDS) to

determine appropriate precautions to prevent hazardous conditions during product application. Personal

protective equipment (PPE) used during cleaning and housekeeping procedures should be appropriate to

the task.

Housekeeping surfaces can be divided into two groups – those with minimal hand-contact (e.g., floors,

and ceilings) and those with frequent hand-contact (“high touch surfaces”). The methods, thoroughness,

and frequency of cleaning and the products used are determined by health-care facility policy.

However, high-touch housekeeping surfaces in patient-care areas (e.g., doorknobs, bedrails, light

switches, wall areas around the toilet in the patient’s room, and the edges of privacy curtains) should be

cleaned and/or disinfected more frequently than surfaces with minimal hand contact. Infection-control

practitioners typically use a risk-assessment approach to identify high-touch surfaces and then

coordinate an appropriate cleaning and disinfecting strategy and schedule with the housekeeping staff.

Horizontal surfaces with infrequent hand contact (e.g., window sills and hard-surface flooring) in

routine patient-care areas require cleaning on a regular basis, when soiling or spills occur, and when a

patient is discharged from the facility.

Regular cleaning of surfaces and decontamination, as needed, is

also advocated to protect potentially exposed workers.

967

Cleaning of walls, blinds, and window

curtains is recommended when they are visibly soiled.

972, 973, 975

Disinfectant fogging is not

recommended for general infection control in routine patient-care areas.

2, 976

Further,

paraformaldehyde, which was once used in this application, is no longer registered by EPA for this

purpose. Use of paraformaldehyde in these circumstances requires either registration or an exemption

issued by EPA under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Infection

control, industrial hygienists, and environmental services supervisors should assess the cleaning

procedures, chemicals used, and the safety issues to determine if a temporary relocation of the patient is

needed when cleaning in the room.

Extraordinary cleaning and decontamination of floors in health-care settings is unwarranted. Studies

have demonstrated that disinfection of floors offers no advantage over regular detergent/water cleaning

and has minimal or no impact on the occurrence of health-care–associated infections.

947, 948, 977–980

Additionally, newly cleaned floors become rapidly recontaminated from airborne microorganisms and

those transferred from shoes, equipment wheels, and body substances.

971, 975, 981

Nevertheless, health-

care institutions or contracted cleaning companies may choose to use an EPA-registered

detergent/disinfectant for cleaning low-touch surfaces (e.g., floors) in patient-care areas because of the

difficulty that personnel may have in determining if a spill contains blood or body fluids (requiring a

detergent/disinfectant for clean-up) or when a multi-drug resistant organism is likely to be in the

environment. Methods for cleaning non-porous floors include wet mopping and wet vacuuming, dry

dusting with electrostatic materials, and spray buffing.

973, 982–984

Methods that produce minimal mists

and aerosols or dispersion of dust in patient-care areas are preferred.

9, 20, 109, 272

Part of the cleaning strategy is to minimize contamination of cleaning solutions and cleaning tools.

Bucket solutions become contaminated almost immediately during cleaning, and continued use of the

solution transfers increasing numbers of microorganisms to each subsequent surface to be cleaned.

971, 981,

985

Cleaning solutions should be replaced frequently. A variety of “bucket” methods have been devised

to address the frequency with which cleaning solutions are replaced.

986, 987

Another source of

contamination in the cleaning process is the cleaning cloth or mop head, especially if left soaking in

dirty cleaning solutions.

971, 988–990

Laundering of cloths and mop heads after use and allowing them to

dry before re-use can help to minimize the degree of contamination.

990

A simplified approach to

cleaning involves replacing soiled cloths and mop heads with clean items each time a bucket of

detergent/disinfectant is emptied and replaced with fresh, clean solution (B. Stover, Kosair Children’s

Hospital, 2000). Disposable cleaning cloths and mop heads are an alternative option, if costs permit.

Another reservoir for microorganisms in the cleaning process may be dilute solutions of the detergents

or disinfectants, especially if the working solution is prepared in a dirty container, stored for long

periods of time, or prepared incorrectly.

547

Gram-negative bacilli (e.g.,

Pseudomonas

spp. and

Serratia

marcescens

) have been detected in solutions of some disinfectants (e.g., phenolics and quaternary

ammonium compounds).

547, 991

Contemporary EPA registration regulations have helped to minimize

this problem by asking manufacturers to provide potency data to support label claims for

detergent/disinfectant properties under real- use conditions (e.g., diluting the product with tap water

instead of distilled water). Application of contaminated cleaning solutions, particularly from small-

quantity aerosol spray bottles or with equipment that might generate aerosols during operation, should

be avoided, especially in high-risk patient areas.

992, 993

Making sufficient fresh cleaning solution for

daily cleaning, discarding any remaining solution, and drying out the container will help to minimize the

degree of bacterial contamination. Containers that dispense liquid as opposed to spray-nozzle

dispensers (e.g., quart-sized dishwashing liquid bottles) can be used to apply detergent/disinfectants to

surfaces and then to cleaning cloths with minimal aerosol generation. A pre-mixed, “ready-to-use”

detergent/disinfectant solution may be used if available.

c. Cleaning Special Care Areas

Guidelines have been published regarding cleaning strategies for isolation areas and operating rooms.

6, 7

The basic strategies for areas housing immunosuppressed patients include a) wet dusting horizontal

surfaces daily with cleaning cloths pre-moistened with detergent or an EPA-registered hospital

disinfectant or disinfectant wipes;

94, 98463

b) using care when wet dusting equipment and surfaces above

the patient to avoid patient contact with the detergent/disinfectant; c) avoiding the use of cleaning

equipment that produces mists or aerosols; d) equipping vacuums with HEPA filters, especially for the

exhaust, when used in any patient-care area housing immunosuppressed patients;

9, 94, 986

and e) regular

cleaning and maintenance of equipment to ensure efficient particle removal. When preparing the

cleaning cloths for wet-dusting, freshly prepared solutions of detergents or disinfectants should be used

rather than cloths that have soaked in such solutions for long periods of time. Dispersal of

microorganisms in the air from dust or aerosols is more problematic in these settings than elsewhere in

health-care facilities. Vacuum cleaners can serve as dust disseminators if they are not operating

properly.

994

Doors to immunosuppressed patients’ rooms should be closed when nearby areas are being

vacuumed.

Bacterial and fungal contamination of filters in cleaning equipment is inevitable, and these

filters should be cleaned regularly or replaced as per equipment manufacturer instructions.

Mats with tacky surfaces placed in operating rooms and other patient-care areas only slightly minimize

the overall degree of contamination of floors and have little impact on the incidence rate of health-care–

associated infection in general.

351, 971, 983

An exception, however, is the use of tacky mats inside the

entry ways of cordoned-off construction areas inside the health-care facility; these mats help to

minimize the intrusion of dust into patient-care areas.

Special precautions for cleaning incubators, mattresses, and other nursery surfaces have been

recommended to address reports of hyperbilirubinemia in newborns linked to inadequately diluted

solutions of phenolics and poor ventilation.

995–997

These medical conditions have not, however, been

associated with the use of properly prepared solutions of phenolics. Non-porous housekeeping surfaces

in neonatal units can be disinfected with properly diluted or pre-mixed phenolics, followed by rinsing

with clean water.

997

However, phenolics are not recommended for cleaning infant bassinets and

incubators during the stay of the infant. Infants who remain in the nursery for an extended period

should be moved periodically to freshly cleaned and disinfected bassinets and incubators.

997

phenolics are used for cleaning bassinets and incubators after they have been vacated, the surfaces

should be rinsed thoroughly with water and dried before either piece of equipment is reused. Cleaning

and disinfecting protocols should allow for the full contact time specified for the product used. Bassinet

mattresses should be replaced, however, if the mattress cover surface is broken.

997

3. Cleaning Strategies for Spills of Blood and Body Substances

Neither HBV, HCV, nor HIV has ever been transmitted from a housekeeping surface (i.e., floors, walls,

or countertops). Nonetheless, prompt removal and surface disinfection of an area contaminated by

either blood or body substances are sound infection-control practices and OSHA requirements.

967

Studies have demonstrated that HIV is inactivated rapidly after being exposed to commonly used

chemical germicides at concentrations that are much lower than those used in practice.

998–1003

HBV is

readily inactivated with a variety of germicides, including quaternary ammonium compounds.

1004

Embalming fluids (e.g., formaldehyde) are also capable of completely inactivating HIV and HBV.

1005,

1006

OSHA has revised its regulation for disinfecting spills of blood or other potentially infectious

material to include proprietary products whose label includes inactivation claims for HBV and HIV,

provided that such surfaces have not become contaminated with agent(s) or volumes of or

concentrations of agent(s) for which a higher level of disinfection is recommended.

1007

These

registered products are listed in EPA’s List D –

Registered Antimicrobials Effective Against Hepatitis B

Virus and Human HIV-1

, which may include products tested against duck hepatitis B virus (DHBV) as a

surrogate for HBV.

1008, 1009

Additional lists of interest include EPA’s List C –

Registered Antimicrobials

Effective Against Human HIV-1

and EPA’s List E –

Registered Antimicrobials Effective Against

Mycobacterium spp., Hepatitis B Virus, and Human HIV-1

Sodium hypochlorite solutions are inexpensive and effective broad-spectrum germicidal solutions.

1010,

1011

Generic sources of sodium hypochlorite include household chlorine bleach or reagent grade

chemical. Concentrations of sodium hypochlorite solutions with a range of 5,000–6,150 ppm (1:10 v/v

dilution of household bleaches marketed in the United States) to 500–615 ppm (1:100 v/v dilution) free

chlorine are effective depending on the amount of organic material (e.g., blood, mucus, and urine)

present on the surface to be cleaned and disinfected.

1010, 1011

EPA-registered chemical germicides may

be more compatible with certain materials that could be corroded by repeated exposure to sodium

hypochlorite, especially the 1:10 dilution. Appropriate personal protective equipment (e.g., gloves and

goggles) should be worn when preparing and using hypochlorite solutions or other chemical

germicides.

967

Despite laboratory evidence demonstrating adequate potency against bloodborne pathogens (e.g., HIV

and HBV), many chlorine bleach products available in grocery and chemical-supply stores are not

registered by the EPA for use as surface disinfectants. Use of these chlorine products as surface

disinfectants is considered by the EPA to be an “unregistered use.” EPA encourages the use of

registered products because the agency reviews them for safety and performance when the product is

used according to label instructions. When unregistered products are used for surface disinfection, users

do so at their own risk.

Strategies for decontaminating spills of blood and other body fluids differ based on the setting in which

they occur and the volume of the spill.

1010

In patient-care areas, workers can manage small spills with

cleaning and then disinfecting using an intermediate-level germicide or an EPA-registered germicide

from the EPA List D or E.

967, 1007

For spills containing large amounts of blood or other body

substances, workers should first remove visible organic matter with absorbent material (e.g., disposable

paper towels discarded into leak-proof, properly labeled containment) and then clean and decontaminate

the area.

1002, 1003, 1012

If the surface is nonporous and a generic form of a sodium hypochlorite solution is

used (e.g., household bleach), a 1:100 dilution is appropriate for decontamination assuming that a) the

worker assigned to clean the spill is wearing gloves and other personal protective equipment appropriate

to the task, b) most of the organic matter of the spill has been removed with absorbent material, and c)

the surface has been cleaned to remove residual organic matter. A recent study demonstrated that even

strong chlorine solutions (i.e., 1:10 dilution of chlorine bleach) may fail to totally inactivate high titers

of virus in large quantities of blood, but in the absence of blood these disinfectants can achieve complete

viral inactivation.

1011

This evidence supports the need to remove most organic matter from a large spill

before final disinfection of the surface. Additionally, EPA-registered proprietary disinfectant label

claims are based on use on a pre-cleaned surface.

951, 954

Managing spills of blood, body fluids, or other infectious materials in clinical, public health, and

research laboratories requires more stringent measures because of a) the higher potential risk of disease

transmission associated with large volumes of blood and body fluids and b) high numbers of

microorganisms associated with diagnostic cultures. The use of an intermediate-level germicide for

routine decontamination in the laboratory is prudent.

954

Recommended practices for managing large

spills of concentrated infectious agents in the laboratory include a) confining the contaminated area, b)

flooding the area with a liquid chemical germicide before cleaning, and c) decontaminating with fresh

germicidal chemical of at least intermediate-level disinfectant potency.

1010

A suggested technique when

flooding the spill with germicide is to lay absorbent material down on the spill and apply sufficient

germicide to thoroughly wet both the spill and the absorbent material.

1013

If using a solution of

household chlorine bleach, a 1:10 dilution is recommended for this purpose. EPA-registered germicides

should be used according to the manufacturers’ instructions for use dilution and contact time. Gloves

should be worn during the cleaning and decontamination procedures in both clinical and laboratory

settings. PPE in such a situation may include the use of respiratory protection (e.g., an N95 respirator)

if clean-up procedures are expected to generate infectious aerosols. Protocols for cleaning spills should

be developed and made available on record as part of good laboratory practice.

1013

Workers in

laboratories and in patient-care areas of the facility should receive periodic training in environmental-

surface infection-control strategies and procedures as part of an overall infection-control and safety

curriculum.

4. Carpeting and Cloth Furnishings

a. Carpeting

Carpeting has been used for more than 30 years in both public and patient-care areas of health-care

facilities. Advantages of carpeting in patient-care areas include a) its noise-limiting characteristics; b)

the “humanizing” effect on health care; and c) its contribution to reductions in falls and resultant

injuries, particularly for the elderly.

1014–1016

Compared to hard-surface flooring, however, carpeting is

harder to keep clean, especially after spills of blood and body substances. It is also harder to push

equipment with wheels (e.g., wheelchairs, carts, and gurneys) on carpeting.

Several studies have documented the presence of diverse microbial populations, primarily bacteria and

fungi, in carpeting;

111, 1017–1024

the variety and number of microorganisms tend to stabilize over time.

New carpeting quickly becomes colonized, with bacterial growth plateauing after about 4 weeks.

1019

Vacuuming and cleaning the carpeting can temporarily reduce the numbers of bacteria, but these

populations soon rebound and return to pre-cleaning levels.

1019, 1020, 1023

Bacterial contamination tends

to increase with higher levels of activity.

1018–1020, 1025

Soiled carpeting that is or remains damp or wet

provides an ideal setting for the proliferation and persistence of gram-negative bacteria and fungi.

1026

Carpeting that remains damp should be removed, ideally within 72 hours.

Despite the evidence of bacterial growth and persistence in carpeting, only limited epidemiologic

evidence demonstrates that carpets influence health-care–associated infection rates in areas housing

immunocompetent patients.

1023, 1025, 1027

This guideline, therefore, includes no recommendations against

the use of carpeting in these areas. Nonetheless, avoiding the use of carpeting is prudent in areas where

spills are likely to occur (e.g., laboratories, areas around sinks, and janitor closets) and where patients

may be at greater risk of infection from airborne environmental pathogens (e.g., HSCT units, burn units,

ICUs, and ORs).

111, 1028

An outbreak of aspergillosis in an HSCT unit was recently attributed to carpet

contamination and a particular method of carpet cleaning.

111

A window in the unit had been opened

repeatedly during the time of a nearby building fire, which allowed fungal spore intrusion into the unit.

After the window was sealed, the carpeting was cleaned using a “bonnet buffing” machine, which

dispersed

Aspergillus

spores into the air.

111

Wet vacuuming was instituted, replacing the dry cleaning

method used previously; no additional cases of invasive aspergillosis were identified.

The care setting and the method of carpet cleaning are important factors to consider when attempting to

minimize or prevent production of aerosols and dispersal of carpet microorganisms into the air.

94, 111

Both vacuuming and shampooing or wet cleaning with equipment can disperse microorganisms to the

air.

111, 994

Vacuum cleaners should be maintained to minimize dust dispersal in general, and be

equipped with HEPA filters, especially for use in high-risk patient-care areas.

9, 94, 986

Some

formulations of carpet-cleaning chemicals, if applied or used improperly, can be dispersed into the air as

a fine dust capable of causing respiratory irritation in patients and staff.

1029

Cleaning equipment,

especially those that engage in wet cleaning and extraction, can become contaminated with waterborne

organisms (e.g.,

Pseudomonas aeruginosa

) and serve as a reservoir for these organisms if this

equipment is not properly maintained. Substantial numbers of bacteria can then be transferred to

carpeting during the cleaning process.

1030

Therefore, keeping the carpet cleaning equipment in good

repair and allowing such equipment to dry between uses is prudent.

Carpet cleaning should be performed on a regular basis determined by internal policy. Although spills

of blood and body substances on non-porous surfaces require prompt spot cleaning using standard

cleaning procedures and application of chemical germicides,

967

similar decontamination approaches to

blood and body substance spills on carpeting can be problematic from a regulatory perspective.

1031

Most, if not all, modern carpet brands suitable for public facilities can tolerate the activity of a variety of

liquid chemical germicides. However, according to OSHA, carpeting contaminated with blood or other

potentially infectious materials can not be fully decontaminated.

1032

Therefore, facilities electing to use

carpeting for high-activity patient-care areas may choose carpet tiles in areas at high risk for spills.

967,

1032

In the event of contamination with blood or other body substances, carpet tiles can be removed,

discarded, and replaced. OSHA also acknowledges that only minimal direct skin contact occurs with

carpeting, and therefore, employers are expected to make reasonable efforts to clean and sanitize

carpeting using carpet detergent/cleaner products.

1032

Over the last few years, some carpet manufacturers have treated their products with fungicidal and/or

bactericidal chemicals. Although these chemicals may help to reduce the overall numbers of bacteria or

fungi present in carpet, their use does not preclude the routine care and maintenance of the carpeting.

Limited evidence suggests that chemically treated carpet may have helped to keep health-care–

associated aspergillosis rates low in one HSCT unit,

111

but overall, treated carpeting has not been shown

to prevent the incidence of health-care–associated infections in care areas for immunocompetent

patients.

b. Cloth Furnishings

Upholstered furniture and furnishings are becoming increasingly common in patient-care areas. These

furnishings range from simple cloth chairs in patients’ rooms to a complete decorating scheme that

gives the interior of the facility more the look of an elegant hotel.

1033

Even though pathogenic

microorganisms have been isolated from the surfaces of cloth chairs, no epidemiologic evidence

suggests that general patient-care areas with cloth furniture pose increased risks of health-care–

associated infection compared with areas that contain hard-surfaced furniture.

1034, 1035

Allergens (e.g.,

dog and cat dander) have been detected in or on cloth furniture in clinics and elsewhere in hospitals in

concentrations higher than those found on bed linens.

1034, 1035

These allergens presumably are

transferred from the clothing of visitors. Researchers have therefore suggested that cloth chairs should

be vacuumed regularly to keep the dust and allergen levels to a minimum. This recommendation,

however, has generated concerns that aerosols created from vacuuming could place

immunocompromised patients or patients with preexisting lung disease (e.g., asthma) at risk for

development of health-care–associated, environmental airborne disease.

9, 20, 109, 988

Recovering worn,

upholstered furniture (especially the seat cushion) with covers that are easily cleaned (e.g., vinyl), or

replacing the item is prudent; minimizing the use of upholstered furniture and furnishings in any patient-

care areas where immunosuppressed patients are located (e.g., HSCT units) reduces the likelihood of

disease.

5. Flowers and Plants in Patient-Care Areas

Fresh flowers, dried flowers, and potted plants are common items in health-care facilities. In 1974,

clinicians isolated an

Erwinia

sp. post mortem from a neonate diagnosed with fulminant septicemia,

meningitis, and respiratory distress syndrome.

1038

Because

Erwinia

spp. are plant pathogens, plants

brought into the delivery room were suspected to be the source of the bacteria, although the case report

did not definitively establish a direct link. Several subsequent studies evaluated the numbers and

diversity of microorganisms in the vase water of cut flowers. These studies revealed that high

concentrations of bacteria, ranging from 10

–10

CFU/mL, were often present, especially if the water

was changed infrequently.

515, 702, 1039

The major group of microorganisms in flower vase water was

gram-negative bacteria, with

Pseudomonas aeruginosa

the most frequently isolated organism.

515, 702, 1039,

1040

P. aeruginosa

was also the primary organism directly isolated from chrysanthemums and other

potted plants.

1041, 1042

However, flowers in hospitals were not significantly more contaminated with

bacteria compared with flowers in restaurants or in the home.

702

Additionally, no differences in the

diversity and degree of antibiotic resistance of bacteria have been observed in samples isolated from

hospital flowers versus those obtained from flowers elsewhere.

702

Despite the diversity and large numbers of bacteria associated with flower-vase water and potted plants,

minimal or no evidence indicates that the presence of plants in immunocompetent patient-care areas

poses an increased risk of health-care–associated infection.

515

In one study involving a limited number

of surgical patients, no correlation was observed between bacterial isolates from flowers in the area and

the incidence and etiology of postoperative infections among the patients.

1040

Similar conclusions were

reached in a study that examined the bacteria found in potted plants.

1042

Nonetheless, some precautions

for general patient-care settings should be implemented, including a) limiting flower and plant care to

staff with no direct patient contact, b) advising health-care staff to wear gloves when handling plants, c)

washing hands after handling plants, d) changing vase water every 2 days and discharging the water into

a sink outside the immediate patient environment, and e) cleaning and disinfecting vases after use.

702

Some researchers have examined the possibility of adding a chemical germicide to vase water to control

bacterial populations. Certain chemicals (e.g., hydrogen peroxide and chlorhexidine) are well tolerated

by plants.

1040, 1043, 1044

Use of these chemicals, however, was not evaluated in studies to assess impact on

health-care–associated infection rates. Modern florists now have a variety of products available to add

to vase water to extend the life of cut flowers and to minimize bacterial clouding of the water.

Flowers (fresh and dried) and ornamental plants, however, may serve as a reservoir of

Aspergillus

spp.,

and dispersal of conidiospores into the air from this source can occur.

109

Health-care–associated

outbreaks of invasive aspergillosis reinforce the importance of maintaining an environment as free of

Aspergillus

spp. spores as possible for patients with severe, prolonged neutropenia. Potted plants, fresh-

cut flowers, and dried flower arrangements may provide a reservoir for these fungi as well as other

fungal species (e.g.,

Fusarium

spp.).

109, 1045, 1046

Researchers in one study of bacteria and flowers

suggested that flowers and vase water should be avoided in areas providing care to medically at-risk

patients (e.g., oncology patients and transplant patients), although this study did not attempt to correlate

the observations of bacterial populations in the vase water with the incidence of health-care–associated

infections.

515

Another study using molecular epidemiology techniques demonstrated identical

Aspergillus terreus

types among environmental and clinical specimens isolated from infected patients

with hematological malignancies.

1046

Therefore, attempts should be made to exclude flowers and plants

from areas where immunosuppressed patients are be located (e.g., HSCT units).

9, 1046

6. Pest Control

Cockroaches, flies and maggots, ants, mosquitoes, spiders, mites, midges, and mice are among the

typical arthropod and vertebrate pest populations found in health-care facilities. Insects can serve as

agents for the mechanical transmission of microorganisms, or as active participants in the disease

transmission process by serving as a vector.

1047–1049

Arthropods recovered from health-care facilities

have been shown to carry a wide variety of pathogenic microorganisms.

1050–1056

Studies have suggested

that the diversity of microorganisms associated with insects reflects the microbial populations present in

the indoor health-care environment; some pathogens encountered in insects from hospitals were either

absent from or present to a lesser degree in insects trapped from residential settings.

1057–1060

Some of

the microbial populations associated with insects in hospitals have demonstrated resistance to

antibiotics.

1048, 1059, 1061–1063

Insect habitats are characterized by warmth, moisture, and availability of food.

1064

Insects forage in and

feed on substrates, including but not limited to food scraps from kitchens/cafeteria, foods in vending

machines, discharges on dressings either in use or discarded, other forms of human detritis, medical

wastes, human wastes, and routine solid waste.

1057–1061

Cockroaches, in particular, have been known to

feed on fixed sputum smears in laboratories.

1065, 1066

Both cockroaches and ants are frequently found in

the laundry, central sterile supply departments, and anywhere in the facility where water or moisture is

present (e.g., sink traps, drains and janitor closets). Ants will often find their way into sterile packs of

items as they forage in a warm, moist environment.

1057

Cockroaches and other insects frequent loading

docks and other areas with direct access to the outdoors.

Although insects carry a wide variety of pathogenic microorganisms on their surfaces and in their gut,

the direct association of insects with disease transmission (apart from vector transmission) is limited,

especially in health-care settings; the presence of insects in itself likely does not contribute substantially

to health-care–associated disease transmission in developed countries. However, outbreaks of infection

attributed to microorganisms carried by insects may occur because of infestation coupled with breaks in

standard infection-control practices.

1063

Studies have been conducted to examine the role of houseflies

as possible vectors for shigellosis and other forms of diarrheal disease in non-health–care settings.

1046,

1067

When control measures aimed at reducing the fly population density were implemented, a

concomitant reduction in the incidence of diarrheal infections, carriage of

Shigella

organisms, and

mortality caused by diarrhea among infants and young children was observed.

Myiasis is defined as a parasitosis in which the larvae of any of a variety of flies use living or necrotic

tissue or body substances of the host as a nutritional source.

1068

Larvae from health-care–acquired

myiasis have been observed in nares, wounds, eyes, ears, sinuses, and the external urogenital

structures.

1069–1071

Patients with this rare condition are typically older adults with underlying medical

conditions (e.g., diabetes, chronic wounds, and alcoholism) who have a decreased capacity to ward off

the flies. Persons with underlying conditions who live or travel to tropical regions of the world are

especially at risk.

1070, 1071

Cases occur in the summer and early fall months in temperate climates when

flies are most active.

1071

An environmental assessment and review of the patient’s history are necessary

to verify that the source of the myiasis is health-care–acquired and to identify corrective measures.

1069,

1072

Simple prevention measures (e.g., installing screens on windows) are important in reducing the

incidence of myiasis.

1072

From a public health and hygiene perspective, arthropod and vertebrate pests should be eradicated from

all indoor environments, including health-care facilities.

1073, 1074

Modern approaches to institutional

pest management usually focus on a) eliminating food sources, indoor habitats, and other conditions that

attract pests; b) excluding pests from the indoor environments; and c) applying pesticides as needed.

1075

Sealing windows in modern health-care facilities helps to minimize insect intrusion. When windows

need to be opened for ventilation, ensuring that screens are in good repair and closing doors to the

outside can help with pest control. Insects should be kept out of all areas of the health-care facility,

especially ORs and any area where immunosuppressed patients are located. A pest-control specialist

with appropriate credentials can provide a regular insect-control program that is tailored to the needs of

the facility and uses approved chemicals and/or physical methods. Industrial hygienists can provide

information on possible adverse reactions of patients and staff to pesticides and suggest alternative

methods for pest control, as needed.

7. Special Pathogen Concerns

a. Antibiotic-Resistant Gram-Positive Cocci

Vancomycin-resistant enterococci (VRE), methicillin-resistant

Staphylococcus aureus

(MRSA), and

aureus

with intermediate levels of resistance to glycopeptide antibiotics (vancomycin intermediate

resistant

S. aureus

[VISA] or glycopeptide intermediate resistant

S. aureus

[GISA]) represent crucial

and growing concerns for infection control. Although the term GISA is technically a more accurate

description of the strains isolated to date (most of which are classified as having intermediate resistance

to both vancomycin and teicoplanin), the term “glycopeptide” may not be recognized by many

clinicians. Thus, the label of VISA, which emphasizes a change in minimum inhibitory concentration

(MICs) to vancomycin, is similar to that of VRE and is more meaningful to clinicians.

1076

According to

National Nosocomial Infection Surveillance (NNIS) statistics for infections acquired among ICU

patients in the United States in 1999, 52.3% of infections resulting from

S. aureus

were identified as

MRSA infections, and 25.2% of enterococcal infections were attributed to VRE. These figures reflect a

37% and a 43% increase, respectively, since 1994–1998.

1077

People represent the primary reservoir of

S. aureus

1078

Although

S. aureus

has been isolated from a

variety of environmental surfaces (e.g., stethoscopes, floors, charts, furniture, dry mops, and

hydrotherapy tanks), the role of environmental contamination in transmission of this organism in health

care appears to be minimal.

1079–1082

S. aureus

contamination of surfaces and tanks within burn therapy

units, however, may be a major factor in the transmission of infection among burn patients.

1083

Colonized patients are the principal reservoir of VRE, and patients who are immunosuppressed (e.g.,

transplant patients) or otherwise medically at-risk (e.g., ICU patients, cardio-thoracic surgical patients,

patients previously hospitalized for extended periods, and those having received multi-antimicrobial or

vancomycin therapy) are at greatest risk for VRE colonization.

1084–1087

The mechanisms by which

cross-colonization take place are not well defined, although recent studies have indicated that both

MRSA and VRE may be transmitted either a) directly from patient to patient, b) indirectly by transient

carriage on the hands of health-care workers,

1088–1091

or c) by hand transfer of these gram-positive

organisms from contaminated environmental surfaces and patient-care equipment.

1084, 1087, 1092–1097

one survey, hand carriage of VRE in workers in a long-term care facility ranged from 13%–41%.

1098

Many of the environmental surfaces found to be contaminated with VRE in outbreak investigations have

been those that are touched frequently by the patient or the health-care worker.

1099

Such high-touch

surfaces include bedrails, doorknobs, bed linens, gowns, overbed tables, blood pressure cuffs, computer

table, bedside tables, and various medical equipment.

22, 1087, 1094, 1095, 1100–1102

Contamination of

environmental surfaces with VRE generally occurs in clinical laboratories and areas where colonized

patients are present,

1087, 1092, 1094, 1095, 1103

but the potential for contamination increases when such patients

have diarrhea

1087

or have multiple body-site colonization.

1104

Additional factors that can be important

in the dispersion of these pathogens to environmental surfaces are misuse of glove techniques by health-

care workers (especially when cleaning fecal contamination from surfaces) and patient, family, and

visitor hygiene.

Interest in the importance of environmental reservoirs of VRE increased when laboratory studies

demonstrated that enterococci can persist in a viable state on dry environmental surfaces for extended

periods of time (7 days to 4 months)

1099, 1105

and multiple strains can be identified during extensive

periods of surveillance.

1104

VRE can be recovered from inoculated hands of health-care workers (with

or without gloves) for up to 60 minutes.

The presence of either MRSA, VISA, or VRE on

environmental surfaces, however, does not mean that patients in the contaminated areas will become

colonized. Strict adherence to hand hygiene/handwashing and the proper use of barrier precautions help

to minimize the potential for spread of these pathogens. Published recommendations for preventing the

spread of vancomycin resistance address isolation measures, including patient cohorting and

management of patient-care items.

Direct patient-care items (e.g., blood pressure cuffs) should be

disposable whenever possible when used in contact isolation settings for patients with multiply resistant

microorganisms.

1102

Careful cleaning of patient rooms and medical equipment contributes substantially to the overall control

of MRSA, VISA, or VRE transmission. The major focus of a control program for either VRE or MRSA

should be the prevention of hand transfer of these organisms. Routine cleaning and disinfection of the

housekeeping surfaces (e.g., floors and walls) and patient-care surfaces (e.g., bedrails) should be

adequate for inactivation of these organisms. Both MRSA and VRE are susceptible to several EPA-

registered low- and intermediate-level disinfectants (e.g., alcohols, sodium hypochlorite, quaternary

ammonium compounds, phenolics, and iodophors) at recommended use dilutions for environmental

surface disinfection.

1103, 1106–1109

Additionally, both VRE and vancomycin-sensitive enterococci are

equally sensitive to inactivation by chemical germicides,

1106, 1107, 1109

and similar observations have been

made when comparing the germicidal resistance of MRSA to that of either methicillin-sensitive

aureus

(MSSA) or VISA.

1110

The use of stronger solutions of disinfectants for inactivation of either

VRE, MRSA, or VISA is not recommended based on the organisms’ resistance to antibiotics.

1110–1112

VRE from clinical specimens have exhibited some measure of increased tolerance to heat inactivation in

temperature ranges <212ºF (<100ºC);

1106, 1113

however, the clinical significance of these observations is

unclear because the role of cleaning the surface or item prior to heat treatment was not evaluated.

Although routine environmental sampling is not recommended, laboratory surveillance of

environmental surfaces during episodes when VRE contamination is suspected can help determine the

effectiveness of the cleaning and disinfecting procedures. Environmental culturing should be approved

and supervised by the infection-control program in collaboration with the clinical laboratory.

1084, 1087, 1088,

1092, 1096

Two cases of wound infections associated with vancomycin-resistant

Staphylococcus aureus

(VRSA)

determined to be resistant by NCCLS standards for sensitivity/resistance testing were identified in

Michigan and Pennsylvania in 2002.

1114, 1115

These represented isolated cases, and neither the family

members nor the health-care providers of these case-patients had evidence of colonization or infection

with VRSA. Conventional environmental infection-control measures (i.e., cleaning and then

disinfecting surfaces using EPA-registered disinfectants with label claims for

S. aureus

) were used

during the environmental investigation of these two cases;

1110–1112

however, studies have yet to evaluate

the potential intrinsic resistance of these VRSA strains to surface disinfectants.

Standard procedures during terminal cleaning and disinfection of surfaces, if performed incorrectly, may

be inadequate for the elimination of VRE from patient rooms.

1113, 1116–1118

Given the sensitivity of VRE

to hospital disinfectants, current disinfecting protocols should be effective if they are diligently carried

out and properly performed. Health-care facilities should be sure that housekeeping staff use correct

procedures for cleaning and disinfecting surfaces in VRE-contaminated areas, which include using

sufficient amounts of germicide at proper use dilution and allowing adequate contact time.

1118

b. Clostridium difficile

Clostridium difficile

is the most frequent etiologic agent for health-care–associated diarrhea.

1119, 1120

one hospital, 30% of adults who developed health-care–associated diarrhea were positive for

difficile

1121

One recent study employing PCR-ribotyping techniques demonstrated that cases of

difiicile

-acquired diarrhea occurring in the hospital included patients whose infections were attributed to

endogenous

C. difficile

strains and patients whose illnesses were considered to be health-care–

associated infections.

1122

Most patients remain asymptomatic after infection, but the organism

continues to be shed in their stools. Risk factors for acquiring

C. difficile

-associated infection include a)

exposure to antibiotic therapy, particularly with beta-lactam agents;

1123

b) gastrointestinal procedures

and surgery;

1124

c) advanced age; and d) indiscriminate use of antibiotics.

1125–1128

Of all the measures

that have been used to prevent the spread of

C. difficile

-associated diarrhea, the most successful has

been the restriction of the use of antimicrobial agents.

1129, 1130

C. difficile

is an anaerobic, gram-positive bacterium. Normally fastidious in its vegetative state, it is

capable of sporulating when environmental conditions no longer support its continued growth. The

capacity to form spores enables the organism to persist in the environment (e.g., in soil and on dry

surfaces) for extended periods of time. Environmental contamination by this microorganism is well

known, especially in places where fecal contamination may occur.

1131

The environment (especially

housekeeping surfaces) rarely serves as a direct source of infection for patients.

1024, 1132–1136

However,

direct exposure to contaminated patient-care items (e.g., rectal thermometers) and high-touch surfaces in

patients’ bathrooms (e.g., light switches) have been implicated as sources of infection.

1130, 1135, 1136, 1138

Transfer of the pathogen to the patient via the hands of health-care workers is thought to be the most

likely mechanism of exposure.

24, 1133, 1139

Standard isolation techniques intended to minimize enteric

contamination of patients, health-care–workers’ hands, patient-care items, and environmental surfaces

have been published.

1140

Handwashing remains the most effective means of reducing hand

contamination. Proper use of gloves is an ancillary measure that helps to further minimize transfer of

these pathogens from one surface to another.

The degree to which the environment becomes contaminated with

C. difficile

spores is proportional to

the number of patients with

C. difficile

-associated diarrhea,

24, 1132, 1135

although asymptomatic, colonized

patients may also serve as a source of contamination. Few studies have examined the use of specific

chemical germicides for the inactivation of

C. difficile

spores, and no well-controlled trials have been

conducted to determine efficacy of surface disinfection and its impact on health-care–associated

diarrhea. Some investigators have evaluated the use of chlorine-containing chemicals (e.g., 1,000 ppm

hypochlorite at recommended use-dilution, 5,000 ppm sodium hypochlorite [1:10 v/v dilution], 1:100

v/v dilutions of unbuffered hypochlorite, and phosphate-buffered hypochlorite [1,600 ppm]). One of the

studies demonstrated that the number of contaminated environmental sites was reduced by half,

1135

whereas another two studies demonstrated declines in health-care–associated

C. difficile

infections in a

HSCT unit

1141

and in two geriatric medical units

1142

during a period of hypochlorite use. The presence

of confounding factors, however, was acknowledged in one of these studies.

1142

The recommended

approach to environmental infection control with respect to

C. difficile

is meticulous cleaning followed

by disinfection using hypochlorite-based germicides as appropriate.

952, 1130, 1143

However, because no

EPA-registered surface disinfectants with label claims for inactivation of

C. difficile

spores are

available, the recommendation is based on the best available evidence from the scientific literature.

c. Respiratory and Enteric Viruses in Pediatric-Care Settings

Although the viruses mentioned in this guideline are not unique to the pediatric-care setting in health-

care facilities, their prevalence in these areas, especially during the winter months, is substantial.

Children (particularly neonates) are more likely to develop infection and substantial clinical disease

from these agents compared with adults and therefore are more likely to require supportive care during

their illness.

Common respiratory viruses in pediatric-care areas include rhinoviruses, respiratory syncytial virus

(RSV), adenoviruses, influenza viruses, and parainfluenza viruses. Transmission of these viruses occurs

primarily via direct contact with small-particle aerosols or via hand contamination with respiratory

secretions that are then transferred to the nose or eyes. Because transmission primarily requires close

personal contact, contact precautions are appropriate to interrupt transmission.

Hand contamination

can occur from direct contact with secretions or indirectly from touching high-touch environmental

surfaces that have become contaminated with virus from large droplets. The indirect transfer of virus

from one persion to other via hand contact with frequently-touched fomites was demonstrated in a study

using a bacteriophage whose environmental stability approximated that of human viral pathogens (e.g.,

poliovirus and parvovirus).

1144

The impact of this mode of transmission with respect to human

respiratory- and enteric viruses is dependent on the ability of these agents to survive on environmental

surfaces. Infectious RSV has been recovered from skin, porous surfaces, and non-porous surfaces after

30 minutes, 1 hour, and 7 hours, respectively.

1145

Parainfluenza viruses are known to persist for up to 4

hours on porous surfaces and up to 10 hours on non-porous surfaces.

1146

Rhinoviruses can persist on

porous surfaces and non-porous surfaces for approximately 1 and 3 hours respectively; study

participants in a controlled environment became infected with rhinoviruses after first touching a surface

with dried secretions and then touching their nasal or conjunctival mucosa.

1147

Although the efficiency

of direct transmission of these viruses from surfaces in uncontrolled settings remains to be defined,

these data underscore the basis for maintaining regular protocols for cleaning and disinfecting of high-

touch surfaces.

The clinically important enteric viruses encountered in pediatric care settings include enteric

adenovirus, astroviruses, caliciviruses, and rotavirus. Group A rotavirus is the most common cause of

infectious diarrhea in infants and children. Transmission of this virus is primarily fecal-oral, however,

the role of fecally contaminated surfaces and fomites in rotavirus transmission is unclear. During one

epidemiologic investigation of enteric disease among children attending day care, rotavirus

contamination was detected on 19% of inanimate objects in the center.

1148, 1149

In an outbreak in a

pediatric unit, secondary cases of rotavirus infection clustered in areas where children with rotaviral

diarrhea were located.

1150

Astroviruses cause gastroenteritis and diarrhea in newborns and young

children and can persist on fecally contaminated surfaces for several months during periods of relatively

low humidity.

1151, 1152

Outbreaks of small round-structured viruses (i.e., caliciviruses [Norwalk virus

and Norwalk-like viruses]) can affect both patients and staff, with attack rates of >50%.

1153

Routes of

person-to-person transmission include fecal-oral spread and aerosols generated from vomiting.

1154–1156

Fecal contamination of surfaces in care settings can spread large amounts of virus to the environment.

Studies that have attempted to use low- and intermediate-level disinfectants to inactivate rotavirus

suspended in feces have demonstrated a protective effect of high concentrations of organic matter.

1157,

1158

Intermediate-level disinfectants (e.g., alcoholic quaternary ammonium compounds, and chlorine

solutions) can be effective in inactivating enteric viruses provided that a cleaning step to remove most of

the organic matter precedes terminal disinfection.

1158

These findings underscore the need for proper

cleaning and disinfecting procedures where contamination of environmental surfaces with body

substances is likely. EPA-registered surface disinfectants with label claims for these viral agents should

be used in these settings. Using disposable, protective barrier coverings may help to minimize the

degree of surface contamination.

936

d. Severe Acute Respiratory Syndrome (SARS) Virus

In November 2002 an atypical pneumonia of unknown etiology emerged in Asia and subsequently

developed into an international outbreak of respiratory illness among persons in 29 countries during the

first six months of 2003. “Severe acute respiratory syndrome” (SARS) is a viral upper respiratory

infection associated with a newly described coronavirus (SARS-associated Co-V [SARS-CoV]).

SARS-CoV is an enveloped RNA virus. It is present in high titers in respiratory secretions, stool, and

blood of infected persons. The modes of transmission determined from epidemiologic investigations

were primarily forms of direct contact (i.e., large droplet aerosolization and person-to-person contact).

Respiratory secretions were presumed to be the major source of virus in these situations; airborne

transmission of virus has not been completely ruled out. Little is known about the impact of fecal-oral

transmission and SARS.

The epidemiology of SARS-CoV infection is not completely understood, and therefore recommended

infection control and prevention measures to contain the spread of SARS will evolve as new

information becomes available.

1159

At present there is no indication that established strategies for

cleaning (i.e., to remove the majority of bioburden) and disinfecting equipment and environmental

surfaces need to be changed for the environmental infection control of SARS. In-patient rooms housing

SARS patients should be cleaned and disinfected at least daily and at the time of patient transfer or

discharge. More frequent cleaning and disinfection may be indicated for high-touch surfaces and

following aerosol-producing procedures (e.g., intubation, bronchoscopy, and sputum production).

While there are presently no disinfectant products registered by EPA specifically for inactivation of

SARS-CoV, EPA-registered hospital disinfectants that are equivalent to low- and intermediate-level

germicides may be used on pre-cleaned, hard, non-porous surfaces in accordance with manufacturer’s

instructions for environmental surface disinfection. Monitoring adherence to guidelines established for

cleaning and disinfection is an important component of environmental infection control to contain the

spread of SARS.

e. Creutzfeldt-Jakob Disease (CJD) in Patient-Care Areas

Creutzfeldt-Jakob disease (CJD) is a rare, invariably fatal, transmissible spongiform encephalopathy

(TSE) that occurs worldwide with an average annual incidence of 1 case per million population.

1160–1162

CJD is one of several TSEs affecting humans; other diseases in this group include kuru, fatal familial

insomnia, and Gerstmann-Sträussler-Scheinker syndrome. A TSE that affects a younger population

(compared to the age range of CJD cases) has been described primarily in the United Kingdom since

1996.

1163

This variant form of CJD (vCJD) is clinically and neuropathologically distinguishable from

classic CJD; epidemiologic and laboratory evidence suggests a causal association for bovine spongiform

encephalopathy (BSE [Mad Cow disease]) and vCJD.

1163–1166

The agent associated with CJD is a prion, which is an abnormal isoform of a normal protein constituent

of the central nervous system.

1167–1169

The mechanism by which the normal form of the protein is

converted to the abnormal, disease-causing prion is unknown. The tertiary conformation of the

abnormal prion protein appears to confer a heightened degree of resistance to conventional methods of

sterilization and disinfection.

1170, 1171

Although about 90% of CJD cases occur sporadically, a limited number of cases are the result of a

direct exposure to prion-containing material (usually central nervous system tissue or pituitary

hormones) acquired as a result of health care (iatrogenic cases). These cases have been linked to a)

pituitary hormone therapy [from human sources as opposed to hormones prepared through the use of

recombinant technology],

1170–1174

b) transplants of either dura mater or corneas,

1175–1181

and c)

neurosurgical instruments and depth electrodes.

1182–1185

In the cases involving instruments and depth

electrodes, conventional cleaning and terminal reprocessing methods of the day failed to fully inactivate

the contaminating prions and are considered inadequate by today’s standards.

Prion inactivation studies involving whole tissues and tissue homogenates have been conducted to

determine the parameters of physical and chemical methods of sterilization or disinfection necessary for

complete inactivation;

1170, 1186–1191

however, the application of these findings to environmental infection

control in health-care settings is problematic. No studies have evaluated the effectiveness of medical

instrument reprocessing in inactivating prions. Despite a consensus that abnormal prions display some

extreme measure of resistance to inactivation by either physical or chemical methods, scientists disagree

about the exact conditions needed for sterilization. Inactivation studies utilizing whole tissues present

extraordinary challenges to any sterilizing method.

1192

Additionally, the experimental designs of these

studies preclude the evaluation of surface cleaning as a part of the total approach to pathogen

inactivation.

951, 1192

Some researchers have recommended the use of either a 1:2 v/v dilution of sodium hypochorite

(approximately 20,000 ppm), full-strength sodium hypochlorite (50,000–60,000 ppm), or 1–2 N sodium

hydroxide (NaOH) for the inactivation of prions on certain surfaces (e.g., those found in the pathology

laboratory).

1170, 1188

Although these chemicals may be appropriate for the decontamination of

laboratory, operating-room, or autopsy-room surfaces that come into contact with central nervous

system tissue from a known or suspected patient, this approach is not indicated for routine or terminal

cleaning of a room previously occupied by a CJD patient. Both chemicals pose hazards for the health-

care worker doing the decontamination. NaOH is caustic and should not make contact with the skin.

Sodium hypochlorite solutions (i.e., chlorine bleach) can corrode metals (e.g., aluminum). MSDS

information should be consulted when attempting to work with concentrated solutions of either

chemical. Currently, no EPA-registered products have label claims for prion inactivation; therefore, this

guidance is based on the best available evidence from the scientific literature.

Environmental infection-control strategies must based on the principles of the “chain of infection,”

regardless of the disease of concern.

Although CJD is transmissible, it is not highly contagious. All

iatrogenic cases of CJD have been linked to a direct exposure to prion-contaminated central nervous

system tissue or pituitary hormones. The six documented iatrogenic cases associated with instruments

and devices involved neurosurgical instruments and devices that introduced residual contamination

directly to the recipient’s brain. No evidence suggests that vCJD has been transmitted iatrogenically or

that either CJD or vCJD has been transmitted from environmental surfaces (e.g., housekeeping

surfaces). Therefore, routine procedures are adequate for terminal cleaning and disinfection of a CJD

patient’s room. Additionally, in epidemiologic studies involving highly transfused patients, blood was

not identified as a source for prion transmission.

1193–1198

Routine procedures for containing,

decontaminating, and disinfecting surfaces with blood spills should be adequate for proper infection

control in these situations.

951, 1199

Guidance for environmental infection control in ORs and autopsy areas has been published.

1197, 1199

Hospitals should develop risk-assessment procedures to identify patients with known or suspected CJD

in efforts to implement prion-specific infection-control measures for the OR and for instrument

reprocessing.

1200

This assessment also should be conducted for older patients undergoing non-lesionous

neurosurgery when such procedures are being done for diagnosis. Disposable, impermeable coverings

should be used during these autopsies and neurosurgeries to minimize surface contamination. Surfaces

that have become contaminated with central nervous system tissue or cerebral spinal fluid should be

cleaned and decontaminated by a) removing most of the tissue or body substance with absorbent

materials, b) wetting the surface with a sodium hypochlorite solution containing >5,000 ppm or a 1 N

NaOH solution, and c) rinsing thoroughly.

951, 1197–1199, 1201

The optimum duration of contact exposure in

these instances is unclear. Some researchers recommend a 1-hour contact time on the basis of tissue-

inactivation studies,

1197, 1198, 1201

whereas other reviewers of the subject draw no conclusions from this

research.

1199

Factors to consider before cleaning a potentially contaminated surface are a) the degree to

which gross tissue/body substance contamination can be effectively removed and b) the ease with which

the surface can be cleaned.

F. Environmental Sampling

This portion of Part I addresses the basic principles and methods of sampling environmental surfaces

and other environmental sources for microorganisms. The applied strategies of sampling with respect to

environmental infection control have been discussed in the appropriate preceding subsections.

1. General Principles: Microbiologic Sampling of the Environment

Before 1970, U.S. hospitals conducted regularly scheduled culturing of the air and environmental

surfaces (e.g., floors, walls, and table tops).

1202

By 1970, CDC and the American Hospital Association

(AHA) were advocating the discontinuation of routine environmental culturing because rates of health-

care–associated infection had not been associated with levels of general microbial contamination of air

or environmental surfaces, and because meaningful standards for permissible levels of microbial

contamination of environmental surfaces or air did not exist.

1203–1205

During 1970–1975, 25% of U.S.

hospitals reduced the extent of such routine environmental culturing — a trend that has continued.

1206,

1207

Random, undirected sampling (referred to as “routine” in previous guidelines) differs from the current

practice of targeted sampling for defined purposes.

2, 1204

Previous recommendations against routine

sampling were not intended to discourage the use of sampling in which sample collection, culture, and

interpretation are conducted in accordance with defined protocols.

In this guideline, targeted

microbiologic sampling connotes a monitoring process that includes a) a written, defined,

multidisciplinary protocol for sample collection and culturing; b) analysis and interpretation of results

using scientifically determined or anticipatory baseline values for comparison; and c) expected actions

based on the results obtained. Infection control, in conjunction with laboratorians, should assess the

health-care facility’s capability to conduct sampling and determine when expert consultation and/or

services are needed.

Microbiologic sampling of air, water, and inanimate surfaces (i.e., environmental sampling) is an

expensive and time-consuming process that is complicated by many variables in protocol, analysis, and

interpretation. It is therefore indicated for only four situations.

1208

The first is to support an

investigation of an outbreak of disease or infections when environmental reservoirs or fomites are

implicated epidemiologically in disease transmission.

161, 1209, 1210

It is important that such culturing be

supported by epidemiologic data. Environmental sampling, as with all laboratory testing, should not be

conducted if there is no plan for interpreting and acting on the results obtained.

11, 1211, 1212

Linking

microorganisms from environmental samples with clinical isolates by molecular epidemiology is crucial

whenever it is possible to do so.

The second situation for which environmental sampling may be warranted is in research. Well-designed

and controlled experimental methods and approaches can provide new information about the spread of

health-care–associated diseases.

126, 129

A classic example is the study of environmental microbial

contamination that compared health-care–associated infection rates in an old hospital and a new facility

before and shortly after occupancy.

947

The third indication for sampling is to monitor a potentially hazardous environmental condition,

confirm the presence of a hazardous chemical or biological agent, and validate the successful abatement

of the hazard. This type of sampling can be used to: a) detect bioaerosols released from the operation of

health-care equipment (e.g., an ultrasonic cleaner) and determine the success of repairs in containing the

hazard,

1213

b) detect the release of an agent of bioterrorism in an indoor environmental setting and

determine its successful removal or inactivation, and c) sample for industrial hygiene or safety purposes

(e.g., monitoring a “sick building”).

The fourth indication is for quality assurance to evaluate the effects of a change in infection-control

practice or to ensure that equipment or systems perform according to specifications and expected

outcomes. Any sampling for quality-assurance purposes must follow sound sampling protocols and

address confounding factors through the use of properly selected controls. Results from a single

environmental sample are difficult to interpret in the absence of a frame of reference or perspective.

Evaluations of a change in infection-control practice are based on the assumption that the effect will be

measured over a finite period, usually of short duration. Conducting quality-assurance sampling on an

extended basis, especially in the absence of an adverse outcome, is usually unjustified. A possible

exception might be the use of air sampling during major construction periods to qualitatively detect

breaks in environmental infection-control measures. In one study, which began as part of an

investigation of an outbreak of health-care–associated aspergillosis, airborne concentrations of

Aspergillus

spores were measured in efforts to evaluate the effectiveness of sealing hospital doors and

windows during a period of construction of a nearby building.

Other examples of sampling for

quality-assurance purposes may include commissioning newly constructed space in special care areas

(i.e., ORs and units for immunosuppressed patients) or assessing a change in housekeeping practice.

However, the only types of routine environmental microbiologic sampling recommended as part of a

quality-assurance program are a) the biological monitoring of sterilization processes by using bacterial

spores

1214

and b) the monthly culturing of water used in hemodialysis applications and for the final

dialysate use dilution. Some experts also advocate periodic environmental sampling to evaluate the

microbial/particulate quality for regular maintenance of the air handling system (e.g., filters) and to

verify that the components of the system meet manufacturer’s specifications (A. Streifel, University of

Minnesota, 2000). Certain equipment in health-care settings (e.g., biological safety cabinets) may also

be monitored with air flow and particulate sampling to determine performance or as part of adherence to

a certification program; results can then be compared with a predetermined standard of performance.

These measurements, however, usually do not require microbiologic testing.

2. Air Sampling

Biological contaminants occur in the air as aerosols and may include bacteria, fungi, viruses, and

pollens.

1215, 1216

Aerosols are characterized as solid or liquid particles suspended in air. Talking for 5

minutes and coughing each can produce 3,000 droplet nuclei; sneezing can generate approximately

40,000 droplets which then evaporate to particles in the size range of 0.5–12 µm.

137, 1217

Particles in a

biological aerosol usually vary in size from <1 µm to >50 µm. These particles may consist of a single,

unattached organism or may occur in the form of clumps composed of a number of bacteria. Clumps

can also include dust and dried organic or inorganic material. Vegetative forms of bacterial cells and

viruses may be present in the air in a lesser number than bacterial spores or fungal spores. Factors that

determine the survival of microorganisms within a bioaerosol include a) the suspending medium, b)

temperature, c) relative humidity, d) oxygen sensitivity, and e) exposure to UV or electromagnetic

radiation.

1215

Many vegetative cells will not survive for lengthy periods of time in the air unless the

relative humidity and other factors are favorable for survival and the organism is enclosed within some

protective cover (e.g., dried organic or inorganic matter).

1216

Pathogens that resist drying (e.g.,

Staphylococcus

spp.,

Streptococcus

spp., and fungal spores) can survive for long periods and can be

carried considerable distances via air and still remain viable. They may also settle on surfaces and

become airborne again as secondary aerosols during certain activities (e.g., sweeping and bed

making).

1216, 1218

Microbiologic air sampling is used as needed to determine the numbers and types of microorganisms, or

particulates, in indoor air.

289

Air sampling for quality control is, however, problematic because of lack

of uniform air-quality standards. Although airborne spores of

Aspergillus

spp. can pose a risk for

neutropenic patients, the critical number (i.e., action level) of these spores above which outbreaks of

aspergillosis would be expected to occur has not been defined. Health-care professionals considering

the use of air sampling should keep in mind that the results represent indoor air quality at singular points

in time, and these may be affected by a variety of factors, including a) indoor traffic, b) visitors entering

the facility, c) temperature, d) time of day or year, e) relative humidity, f) relative concentration of

particles or organisms, and g) the performance of the air-handling system components. To be

meaningful, air-sampling results must be compared with those obtained from other defined areas,

conditions, or time periods.

Several preliminary concerns must be addressed when designing a microbiologic air sampling strategy

(Box 13). Because the amount of particulate material and bacteria retained in the respiratory system is

largely dependent on the size of the inhaled particles, particle size should be determined when studying

airborne microorganisms and their relation to respiratory infections. Particles >5 µm are efficiently

trapped in the upper respiratory tract and are removed primarily by ciliary action.

1219

Particles <5 µm

in diameter reach the lung, but the greatest retention in the alveoli is of particles 1–2 µm in

diameter.

1220–1222

Box 13. Preliminary concerns for conducting air sampling

• Consider the possible characteristics and conditions of the aerosol, including size range of particles,

relative amount of inert material, concentration of microorganisms, and environmental factors.

• Determine the type of sampling instruments, sampling time, and duration of the sampling program.

• Determine the number of samples to be taken.

• Ensure that adequate equipment and supplies are available.

• Determine the method of assay that will ensure optimal recovery of microorganisms.

• Select a laboratory that will provide proper microbiologic support.

• Ensure that samples can be refrigerated if they cannot be assayed in the laboratory promptly.

Bacteria, fungi, and particulates in air can be identified and quantified with the same methods and

equipment (Table 23). The basic methods include a) impingement in liquids, b) impaction on solid

surfaces, c) sedimentation, d) filtration, e) centrifugation, f) electrostatic precipitation, and g) thermal

precipitation.

1218

Of these, impingement in liquids, impaction on solid surfaces, and sedimentation (on

settle plates) have been used for various air-sampling purposes in health-care settings.

289

Several instruments are available for sampling airborne bacteria and fungi (Box 14). Some of the

samplers are self-contained units requiring only a power supply and the appropriate collecting medium,

but most require additional auxiliary equipment (e.g., a vacuum pump and an airflow measuring device

[i.e., a flowmeter or anemometer]). Sedimentation or depositional methods use settle plates and

therefore need no special instruments or equipment. Selection of an instrument for air sampling requires

a clear understanding of the type of information desired and the particular determinations that must be

made (Box 14). Information may be needed regarding a) one particular organism or all organisms that

may be present in the air, b) the concentration of viable particles or of viable organisms, c) the change in

concentration with time, and d) the size distribution of the collected particles. Before sampling begins,

decisions should be made regarding whether the results are to be qualitative or quantitative. Comparing

quantities of airborne microorganisms to those of outdoor air is also standard operating procedure.

Infection-control professionals, hospital epidemiologists, industrial hygienists, and laboratory

supervisors, as part of a multidisciplinary team, should discuss the potential need for microbial air

sampling to determine if the capacity and expertise to conduct such sampling exists within the facility

and when it is appropriate to enlist the services of an environmental microbiologist consultant.

Table 23. Air sampling methods and examples of equipment*

Method Principle

Suitable for

measuring:

Collection

media or

surface

Rate of

collection

(L/min.)

Auxilliary

equipment

needed+

Points to

consider

Prototype

samplers§

Impingement in

liquids

Air drawn

through a

small jet and

directed

against a

liquid surface

Viable

organisms, and

concentration

over time.

Example use:

sampling water

aerosols to

Legionella

spp.

Buffered

gelatin,

tryptose

saline,

peptone,

nutrient

broth

12.5 Yes

Antifoaming

agent may be

needed.

Ambient

temperature

and humidity

will influence

length of

collection time

Chemical

Corps. All

Glass

Impinger

(AGI)

Impaction on

solid surfaces

Air drawn

into the

sampler;

particles

deposited on

a dry surface

Viable

particles; viable

organisms (on

non-nutrient

surfaces,

limited to

organisms that

resist drying

and spores);

size

measurement,

and

concentration

over time.

Example use:

sampling air for

Aspergillus

spp., fungal

spores

Dry surface,

coated

surfaces, and

agar

28 (sieve)

30–800

(slit)

Yes

Available as

sieve

impactors or

slit impactors.

Sieve

impactors can

be set up to

measure

particle size.

Slit impactors

have a rotating

support stage

for agar plates

to allow for

measurement

concentration

over time.

Andersen Air

Sampler

(sieve

impactor);

TDL,

Cassella MK-

2 (slit

impactors)

Sedimentation

Particles and

micro-

organisms

settle onto

surfaces via

gravity

Viable

particles.

Example uses:

sampling air for

bacteria in the

vicinity of and

during a

medical

procedure;

general

measurements

of microbial air

quality.

Nutrient

media

(agars) on

plates or

slides

–

Simple and

inexpensive;

best suited for

qualitative

sampling;

significant

airborne

fungal spores

are too

buoyant to

settle

efficiently for

collection

using this

method.

Settle plates

Method Principle

Suitable for

measuring:

Collection

media or

surface

Rate of

collection

(L/min.)

Auxilliary

equipment

needed+

Points to

consider

Prototype

samplers§

Filtration

Air drawn

through a

filter unit;

particles

trapped;

0.2 µm pore

size

Viable

particles; viable

organisms (on

non-nutrient

surfaces,

limited to

spores and

organisms that

resist drying);

concentration

over time.

Example use:

air sampling for

Aspergillus

spp., fungal

spores, and dust

Paper,

cellulose,

glass wool,

gelatin foam,

and

membrane

filters

1–50 Yes

Filter must be

agitated first

in rinse fluid

to remove and

disperse

trapped micro-

organisms;

rinse fluid is

assayed; used

more for

sampling dust

and chemicals.

–

Centrifugation

Aerosols

subjected to

centrifugal

force;

particles

impacted

onto a solid

surface

Viable

particles; viable

organisms (on

non-nutrient

surfaces,

limited to

spores and

organisms that

resist drying);

concentration

over time.

Example use:

air sampling for

Aspergillus

spp., and

fungal spores

Coated glass

or plastic

slides, and

agar surfaces

40–50 Yes

Calibration is

difficult and is

done only by

the factory;

relative

comparison of

airborne

contamination

is its general

use.

Biotest RCS

Plus

Electrostatic

precipitation

Air drawn

over an

electro-

statically

charged

surface;

particles

become

charged

Viable

particles; viable

organisms (on

non-nutrient

surfaces,

limited to

spores and

organisms that

resist drying);

concentration

over time

Solid

collecting

surfaces

(glass, and

agar)

85 Yes

High volume

sampling rate,

but equipment

is complex

and must be

handled

carefully; not

practical for

use in health-

care settings.

–

Thermal

precipitation

Air drawn

over a

thermal

gradient;

particles

repelled from

hot surfaces,

settle on

colder

surfaces

Size

measurements

Glass

coverslip,

and electron

microscope

grid

0.003–0.4 Yes

Determine

particle size

by direct

observation;

not frequently

used because

of complex

adjustments

and low

sampling

rates.

–

* Material in this table is compiled from references 289, 1218, 1223, and 1224.

+ Most samplers require a flow meter or anemometer and a vacuum source as auxiliary equipment.

§ Trade names listed are for identification purposes only and are not intended as endorsements by the U.S. Public Health Service.

Box 14. Selecting an air sampling device*

The following factors must be considered when choosing an air sampling instrument:

• Viability and type of the organism to be sampled

• Compatibility with the selected method of analysis

• Sensitivity of particles to sampling

• Assumed concentrations and particle size

• Whether airborne clumps must be broken (i.e., total viable organism count vs. particle count)

• Volume of air to be sampled and length of time sampler is to be continuously operated

• Background contamination

• Ambient conditions

• Sampler collection efficiency

• Effort and skill required to operate sampler

• Availability and cost of sampler, plus back-up samplers in case of equipment malfunction

• Availability of auxiliary equipment and utilities (e.g., vacuum pumps, electricity, and water)

* Material in this box is compiled from reference 1218.

Liquid impinger and solid impactor samplers are the most practical for sampling bacteria, particles, and

fungal spores, because they can sample large volumes of air in relatively short periods of time.

289

Solid

impactor units are available as either “slit” or “sieve” designs. Slit impactors use a rotating disc as

support for the collecting surface, which allows determinations of concentration over time. Sieve

impactors commonly use stages with calibrated holes of different diameters. Some impactor-type

samplers use centrifugal force to impact particles onto agar surfaces. The interior of either device must

be made sterile to avoid inadvertent contamination from the sampler. Results obtained from either

sampling device can be expressed as organisms or particles per unit volume of air (CFU/m

Sampling for bacteria requires special attention, because bacteria may be present as individual

organisms, as clumps, or mixed with or adhering to dust or covered with a protective coating of dried

organic or inorganic substances. Reports of bacterial concentrations determined by air sampling

therefore must indicate whether the results represent individual organisms or particles bearing multiple

cells. Certain types of samplers (e.g., liquid impingers) will completely or partially disintegrate clumps

and large particles; the sampling result will therefore reflect the total number of individual organisms

present in the air.

The task of sizing a bioaerosol is simplified through the use of sieves or slit impactors because these

samplers will separate the particles and microorganisms into size ranges as the sample is collected.

These samplers must, however, be calibrated first by sampling aerosols under similar use conditions.

1225

The use of settle plates (i.e., the sedimentation or depositional method) is not recommended when

sampling air for fungal spores, because single spores can remain suspended in air indefinitely.

289

Settle

plates have been used mainly to sample for particulates and bacteria either in research studies or during

epidemiologic investigations.

161, 1226–1229

Results of sedimentation sampling are typically expressed as

numbers of viable particles or viable bacteria per unit area per the duration of sampling time (i.e.,

CFU/area/time); this method can not quantify the volume of air sampled. Because the survival of

microorganisms during air sampling is inversely proportional to the velocity at which the air is taken

into the sampler,

1215

one advantage of using a settle plate is its reliance on gravity to bring organisms

and particles into contact with its surface, thus enhancing the potential for optimal survival of collected

organisms. This process, however, takes several hours to complete and may be impractical for some

situations.

Air samplers are designed to meet differing measurement requirements. Some samplers are better

suited for one form of measurement than others. No one type of sampler and assay procedure can be

used to collect and enumerate 100% of airborne organisms. The sampler and/or sampling method

chosen should, however, have an adequate sampling rate to collect a sufficient number of particles in a

reasonable time period so that a representative sample of air is obtained for biological analysis. Newer

analytical techniques for assaying air samples include PCR methods and enzyme-linked immunosorbent

assays (ELISAs).

3. Water Sampling

A detailed discussion of the principles and practices of water sampling has been published.

945

Water

sampling in health-care settings is used detect waterborne pathogens of clinical significance or to

determine the quality of finished water in a facility’s distribution system. Routine testing of the water in

a health-care facility is usually not indicated, but sampling in support of outbreak investigations can

help determine appropriate infection-control measures. Water-quality assessments in dialysis settings

have been discussed in this guideline (see Water, Dialysis Water Quality and Dialysate, and Appendix

C).

Health-care facilities that conduct water sampling should have their samples assayed in a laboratory that

uses established methods and quality-assurance protocols. Water specimens are not “static specimens”

at ambient temperature; potential changes in both numbers and types of microbial populations can occur

during transport. Consequently, water samples should be sent to the testing laboratory cold (i.e., at

approximately 39.2°F [4°C]) and testing should be done as soon as practical after collection (preferably

within 24 hours).

Because most water sampling in health-care facilities involves the testing of finished water from the

facility’s distribution system, a reducing agent (i.e., sodium thiosulfate [Na

]) needs to be added to

neutralize residual chlorine or other halogen in the collected sample. If the water contains elevated

levels of heavy metals, then a chelating agent should be added to the specimen. The minimum volume

of water to be collected should be sufficient to complete any and all assays indicated; 100 mL is

considered a suitable minimum volume. Sterile collection equipment should always be used.

Sampling from a tap requires flushing of the water line before sample collection. If the tap is a mixing

faucet, attachments (e.g., screens and aerators) must be removed, and hot and then cold water must be

run through the tap before collecting the sample.

945

If the cleanliness of the tap is questionable,

disinfection with 500–600 ppm sodium hypochlorite (1:100 v/v dilution of chlorine bleach) and flushing

the tap should precede sample collection.

Microorganisms in finished or treated water often are physically damaged (“stressed”) to the point that

growth is limited when assayed under standard conditions. Such situations lead to false-negative

readings and misleading assessments of water quality. Appropriate neutralization of halogens and

chelation of heavy metals are crucial to the recovery of these organisms. The choice of recovery media

and incubation conditions will also affect the assay. Incubation temperatures should be closer to the

ambient temperature of the water rather than at 98.6°F (37°C), and recovery media should be formulated

to provide appropriate concentrations of nutrients to support organisms exhibiting less than rigorous

growth.

945

High-nutrient content media (e.g., blood agar and tryptic soy agar [TSA]) may actually

inhibit the growth of these damaged organisms. Reduced nutrient media (e.g., diluted peptone and

R2A) are preferable for recovery of these organisms.

945

Use of aerobic, heterotrophic plate counts allows both a qualitative and quantitative measurement for

water quality. If bacterial counts in water are expected to be high in number (e.g., during waterborne

outbreak investigations), assaying small quantities using pour plates or spread plates is appropriate.

945

Membrane filtration is used when low-count specimens are expected and larger sampling volumes are

required (>100 mL). The sample is filtered through the membrane, and the filter is applied directly

face-up onto the surface of the agar plate and incubated.

Unlike the testing of potable water supplies for coliforms (which uses standardized test and specimen

collection parameters and conditions), water sampling to support epidemiologic investigations of

disease outbreaks may be subjected to modifications dictated by the circumstances present in the

facility. Assay methods for waterborne pathogens may also not be standardized. Therefore, control or

comparison samples should be included in the experimental design. Any departure from a standard

method should be fully documented and should be considered when interpreting results and developing

strategies. Assay methods specific for clinically significant waterborne pathogens (e.g.,

Legionella

spp.,

Aeromonas

spp,

Pseudomonas

spp., and

Acinetobacter

spp.) are more complicated and costly compared

with both methods used to detect coliforms and other standard indicators of water quality.

4. Environmental Surface Sampling

Routine environmental-surface sampling (e.g., surveillance cultures) in health-care settings is neither

cost-effective nor warranted.

951, 1225

When indicated, surface sampling should be conducted with

multidisciplinary approval in adherence to carefully considered plans of action and policy (Box 15).

Box 15. Undertaking environmental-surface sampling*

The following factors should be considered before engaging in environmental-surface sampling:

• Background information from the literature and present activities (i.e., preliminary results from an

epidemiologic investigation)

• Location of surfaces to be sampled

• Method of sample collection and the appropriate equipment for this task

• Number of replicate samples needed and which control or comparison samples are required

• Parameters of the sample assay method and whether the sampling will be qualitative,

quantitative, or both

• An estimate of the maximum allowable microbial numbers or types on the surface(s) sampled

(refer to the Spaulding classification for devices and surfaces)

• Some anticipation of a corrective action plan

* The material in this box is compiled from reference 1214.

Surface sampling is used currently for research, as part of an epidemiologic investigation, or as part of a

comprehensive approach for specific quality assurance purposes. As a research tool, surface sampling

has been used to determine a) potential environmental reservoirs of pathogens,

564, 1230–1232

b) survival of

microorganisms on surfaces,

1232, 1233

and c) the sources of the environmental contamination.

1023

Some

or all of these approaches can also be used during outbreak investigations.

1232

Discussion of surface

sampling of medical devices and instruments is beyond the scope of this document and is deferred to

future guidelines on sterilization and disinfection issues.

Meaningful results depend on the selection of appropriate sampling and assay techniques.

1214

The

media, reagents, and equipment required for surface sampling are available from any well-equipped

microbiology laboratory and laboratory supplier. For quantitative assessment of surface organisms,

non-selective, nutrient-rich agar media and broth (e.g., TSA and brain-heart infusion broth [BHI] with

or without 5% sheep or rabbit blood supplement) are used for the recovery of aerobic bacteria. Broth

media are used with membrane-filtration techniques. Further sample work-up may require the use of

selective media for the isolation and enumeration of specific groups of microorganisms. Examples of

selective media are MacConkey agar (MAC [selects for gram-negative bacteria]), Cetrimide agar

(selects for

Pseudomonas aeruginosa

), or Sabouraud dextrose- and malt extract agars and broths (select

for fungi). Qualitative determinations of organisms from surfaces require only the use of selective or

non-selective broth media.

Effective sampling of surfaces requires moisture, either already present on the surface to be sampled or

via moistened swabs, sponges, wipes, agar surfaces, or membrane filters.

1214, 1234–1236

Dilution fluids

and rinse fluids include various buffers or general purpose broth media (Table 24). If disinfectant

residuals are expected on surfaces being sampled, specific neutralizer chemicals should be used in both

the growth media and the dilution or rinse fluids. Lists of the neutralizers, the target disinfectant active

ingredients, and the use concentrations have been published.

1214, 1237

Alternatively, instead of adding

neutralizing chemicals to existing culture media (or if the chemical nature of the disinfectant residuals is

unknown), the use of either a) commercially available media including a variety of specific and non-

specific neutralizers or b) double-strength broth media will facilitate optimal recovery of

microorganisms. The inclusion of appropriate control specimens should be included to rule out both

residual antimicrobial activity from surface disinfectants and potential toxicity caused by the presence

of neutralizer chemicals carried over into the assay system.

1214

Table 24. Examples of eluents and diluents for environmental-surface sampling* +

Solutions

Concentration in water

Ringer

Peptone water

Buffered peptone water

Phosphate-buffered saline

Sodium chloride (NaCl)

Calgon Ringer§

Thiosulfate Ringer¶

Water

Tryptic soy broth (TSB)

Brain-heart infusion broth (BHI) supplemented with 0.5%

beef extract

1⁄4 strength

0.1%–1.0%

0.067 M phosphate, 0.43% NaCl, 0.1% peptone

0.02 M phosphate, 0.9% NaCl

0.25%–0.9%

1⁄4 strength

–

* Material in this table is compiled from references 1214 and 1238.

+ A surfactant (e.g., polysorbate [i.e., Tween® 80]) may be added to eluents and diluents. A concentration ranging from 0.01%–0.1% is

generally used, depending on the specific application. Foaming may occur during use.

§ This solution is used for dissolution of calcium alginate swabs.

¶ This solution is used for neutralization of residual chlorine.

Several methods can be used for collecting environmental surface samples (Table 25). Specific step-by-

step discussions of each of the methods have been published.

1214, 1239

For best results, all methods

should incorporate aseptic techniques, sterile equipment, and sterile recovery media.

Table 25. Methods of environmental-surface sampling

Method

Suitable for

appropriate

surface(s)

Assay

technique

Procedural

notes

Points of

interpretation

Available

standards

References

Sample/rinse

Moistened

swab/rinse

Moistened

sponge/rinse

Moistened

wipe/rinse

Non-absorbent

surfaces, corners,

crevices, devices,

and instruments

Large areas and

housekeeping

surfaces (e.g.,

floors or walls)

Large areas and

housekeeping

surfaces (e.g.,

countertops)

Dilutions;

qualitative or

quantitative

assays

Dilutions;

qualitative or

quantitative

assays

Dilutions;

qualitative or

quantitative

assays

Assay multiple

measures areas

or devices with

separate swabs

Vigorously rub a

sterile sponge

over the surface

Use a sterile

wipe

Report results per

measured areas or if

assaying an object,

per the entire sample

site

Report results per

measured area

Report results per

measured area

YES

– food

industry;

– heath

care

YES

– food

industry;

– health

care

YES

– food

industry;

– health

care

1214, 1239–

1242

1214, 1239–

1242

1214, 1239–

1242

Direct
immersion

Small items

capable of being

immersed

Dilutions;

qualitative or

quantitative

assays

Use membrane

filtration if rinse

volume is large

and anticipated

microbiological

concentration is

low

Report results per

item

1214

Containment

Interior surfaces

of containers,

tubes, or bottles

Dilutions;

qualitative or

quantitative

assays

Use membrane

filtration if rinse

volume is large

Evaluate both the

types and numbers

of microorganisms

YES

– food and

industrial

applications for

containers prior

to fill

1214

RODAC*

Previously

cleaned and

sanitized flat,

non-absorbent

surfaces; not

suitable for

irregular surfaces

Direct assay

Overgrowth

occurs if used on

heavily

contaminated

surfaces; use

neutralizers in

the agar if

surface

disinfectant

residuals are

present

Provides direct,

quantitative results;

use a minimum of

15 plates per an

average hospital

room

1214, 1237,

1239, 1243,

1244

* RODAC stands for “replicate organism direct agar contact.”

Sample/rinse methods are frequently chosen because of their versatility. However, these sampling

methods are the most prone to errors caused by manipulation of the swab, gauze pad, or sponge.

1238

Additionally, no microbiocidal or microbiostatic agents should be present in any of these items when

used for sampling.

1238

Each of the rinse methods requires effective elution of microorganisms from the

item used to sample the surface. Thorough mixing of the rinse fluids after elution (e.g., via manual or

mechanical mixing using a vortex mixer, shaking with or without glass beads, and ultrasonic bath) will

help to remove and suspend material from the sampling device and break up clumps of organisms for a

more accurate count.

1238

In some instances, the item used to sample the surface (e.g., gauze pad and

sponge) may be immersed in the rinse fluids in a sterile bag and subjected to stomaching.

1238

This

technique, however, is suitable only for soft or absorbent items that will not puncture the bag during the

elution process.

If sampling is conducted as part of an epidemiologic investigation of a disease outbreak, identification

of isolates to species level is mandatory, and characterization beyond the species level is preferred.

1214

When interpreting the results of the sampling, the expected degree of microbial contamination

associated with the various categories of surfaces in the Spaulding classification must be considered.

Environmental surfaces should be visibly clean; recognized pathogens in numbers sufficient to result in

secondary transfer to other animate or inanimate surfaces should be absent from the surface being

sampled.

1214

Although the interpretation of a sample with positive microbial growth is self-evident, an

environmental surface sample, especially that obtained from housekeeping surfaces, that shows no

growth does not represent a “sterile” surface. Sensitivities of the sampling and assay methods (i.e., level

of detection) must be taken into account when no-growth samples are encountered. Properly collected

control samples will help rule out extraneous contamination of the surface sample.

G. Laundry and Bedding

1. General Information

Laundry in a health-care facility may include bed sheets and blankets, towels, personal clothing, patient

apparel, uniforms, scrub suits, gowns, and drapes for surgical procedures.

1245

Although contaminated

textiles and fabrics in health-care facilities can be a source of substantial numbers of pathogenic

microorganisms, reports of health-care–associated diseases linked to contaminated fabrics are so few in

number that the overall risk of disease transmission during the laundry process likely is negligible.

When the incidence of such events are evaluated in the context of the volume of items laundered in

health-care settings (estimated to be 5 billion pounds annually in the United States),

1246

existing control

measures (e.g., standard precautions) are effective in reducing the risk of disease transmission to

patients and staff. Therefore, use of current control measures should be continued to minimize the

contribution of contaminated laundry to the incidence of health-care–associated infections. The control

measures described in this section of the guideline are based on principles of hygiene, common sense,

and consensus guidance; they pertain to laundry services utilized by health-care facilities, either in-

house or contract, rather than to laundry done in the home.

2. Epidemiology and General Aspects of Infection Control

Contaminated textiles and fabrics often contain high numbers of microorganisms from body substances,

including blood, skin, stool, urine, vomitus, and other body tissues and fluids. When textiles are heavily

contaminated with potentially infective body substances, they can contain bacterial loads of 10

–10

CFU/100 cm

of fabric.

1247

Disease transmission attributed to health-care laundry has involved

contaminated fabrics that were handled inappropriately (i.e., the shaking of soiled linens). Bacteria

(

Salmonella

spp.,

Bacillus cereus

), viruses (hepatitis B virus [HBV]), fungi (

Microsporum canis

), and

ectoparasites (scabies) presumably have been transmitted from contaminated textiles and fabrics to

workers via a) direct contact or b) aerosols of contaminated lint generated from sorting and handling

contaminated textiles.

1248–1252

In these events, however, investigations could not rule out the possibility

that some of these reported infections were acquired from community sources. Through a combination

of soil removal, pathogen removal, and pathogen inactivation, contaminated laundry can be rendered

hygienically clean. Hygienically clean laundry carries negligible risk to health-care workers and

patients, provided that the clean textiles, fabric, and clothing are not inadvertently contaminated before

use.

OSHA defines contaminated laundry as “laundry which has been soiled with blood or other potentially

infectious materials or may contain sharps.”

967

The purpose of the laundry portion of the standard is to

protect the worker from exposure to potentially infectious materials during collection, handling, and

sorting of contaminated textiles through the use of personal protective equipment, proper work

practices, containment, labeling, hazard communication, and ergonomics.

Experts are divided regarding the practice of transporting clothes worn at the workplace to the health-

care worker’s home for laundering. Although OSHA regulations prohibit home laundering of items that

are considered personal protective apparel or equipment (e.g., laboratory coats),

967

experts disagree

about whether this regulation extends to uniforms and scrub suits that are not contaminated with blood

or other potentially infectious material. Health-care facility policies on this matter vary and may be

inconsistent with recommendations of professional organizations.

1253, 1254

Uniforms without blood or

body substance contamination presumably do not differ appreciably from street clothes in the degree

and microbial nature of soilage. Home laundering would be expected to remove this level of soil

adequately. However, if health-care facilities require the use of uniforms, they should either make

provisions to launder them or provide information to the employee regarding infection control and

cleaning guidelines for the item based on the tasks being performed at the facility. Health-care

facilities should address the need to provide this service and should determine the frequency for

laundering these items. In a recent study examining the microbial contamination of medical students’

white coats, the students perceived the coats as “clean” as long as the garments were not visibly

contaminated with body substances, even after wearing the coats for several weeks.

1255

The heaviest

bacterial load was found on the sleeves and the pockets of these garments; the organisms most

frequently isolated were

Staphylococcus aureus

, diphtheroids, and

Acinetobacter

spp.

1255

Presumably,

the sleeves of the coat may make contact with a patient and potentially serve to transfer environmentally

stable microorganisms among patients. In this study, however, surveillance was not conducted among

patients to detect new infections or colonizations. The students did, however, report that they would

likely replace their coats more frequently and regularly if clean coats were provided.

1255

Apart from

this study, which documents the presence of pathogenic bacteria on health-care facility clothing, reports

of infections attributed to either the contact with such apparel or with home laundering have been

rare.

1256, 1257

Laundry services for health-care facilities are provided either in-house (i.e., on-premise laundry [OPL]),

co-operatives (i.e., those entities owned and operated by a group of facilities), or by off-site commercial

laundries. In the latter, the textiles may be owned by the health-care facility, in which case the

processor is paid for laundering only. Alternatively, the textiles may be owned by the processor who is

paid for every piece laundered on a “rental” fee. The laundry facility in a health-care setting should be

designed for efficiency in providing hygienically clean textiles, fabrics, and apparel for patients and

staff. Guidelines for laundry construction and operation for health-care facilities, including nursing

facilities, have been published.

120, 1258

The design and engineering standards for existing facilities are

those cited in the AIA edition in effect during the time of the facility’s construction.

120

A laundry

facility is usually partitioned into two separate areas - a “dirty” area for receiving and handling the

soiled laundry and a “clean” area for processing the washed items.

1259

To minimize the potential for

recontaminating cleaned laundry with aerosolized contaminated lint, areas receiving contaminated

textiles should be at negative air pressure relative to the clean areas.

1260–1262

Laundry areas should have

handwashing facilities readily available to workers. Laundry workers should wear appropriate personal

protective equipment (e.g., gloves and protective garments) while sorting soiled fabrics and textiles.

967

Laundry equipment should be used and maintained according to the manufacturer’s instructions to

prevent microbial contamination of the system.

1250, 1263

Damp textiles should not be left in machines

overnight.

1250

3. Collecting, Transporting, and Sorting Contaminated Textiles and Fabrics

The laundry process starts with the removal of used or contaminated textiles, fabrics, and/or clothing

from the areas where such contamination occurred, including but not limited to patients’ rooms,

surgical/operating areas, and laboratories. Handling contaminated laundry with a minimum of agitation

100

can help prevent the generation of potentially contaminated lint aerosols in patient-care areas.

967, 1259

Sorting or rinsing contaminated laundry at the location where contamination occurred is prohibited by

OSHA.

967

Contaminated textiles and fabrics are placed into bags or other appropriate containment in

this location; these bags are then securely tied or otherwise closed to prevent leakage.

967

Single bags of

sufficient tensile strength are adequate for containing laundry, but leak-resistant containment is needed

if the laundry is wet and capable of soaking through a cloth bag.

1264

Bags containing contaminated

laundry must be clearly identified with labels, color-coding, or other methods so that health-care

workers handle these items safely, regardless of whether the laundry is transported within the facility or

destined for transport to an off-site laundry service.

967

Typically, contaminated laundry originating in isolation areas of the hospital is segregated and handled

with special practices; however, few, if any, cases of health-care–associated infection have been linked

to this source.

1265

Single-blinded studies have demonstrated that laundry from isolation areas is no

more heavily contaminated with microorganisms than laundry from elsewhere in the hospital.

1266

Therefore, adherence to standard precautions when handling contaminated laundry in isolation areas and

minimizing agitation of the contaminated items are considered sufficient to prevent the dispersal of

potentially infectious aerosols.

Contaminated textiles and fabrics in bags can be transported by cart or chute.

1258, 1262

Laundry chutes

require proper design, maintenance, and use, because the piston-like action of a laundry bag traveling in

the chute can propel airborne microbial contaminants throughout the facility.

1267–1269

Laundry chutes

should be maintained under negative air pressure to prevent the spread of microorganisms from floor to

floor. Loose, contaminated pieces of laundry should not be tossed into chutes, and laundry bags should

be closed or otherwise secured to prevent the contents from falling out into the chute.

1270

Health-care

facilities should determine the point in the laundry process at which textiles and fabrics should be

sorted. Sorting after washing minimizes the exposure of laundry workers to infective material in soiled

fabrics, reduces airborne microbial contamination in the laundry area, and helps to prevent potential

percutaneous injuries to personnel.

1271

Sorting laundry before washing protects both the machinery and

fabrics from hard objects (e.g., needles, syringes, and patients’ property) and reduces the potential for

recontamination of clean textiles.

1272

Sorting laundry before washing also allows for customization of

laundry formulas based on the mix of products in the system and types of soils encountered.

Additionally, if work flow allows, increasing the amount of segregation by specific product types will

usually yield the greatest amount of work efficiency during inspection, folding, and pack-making

operations.

1253

Protective apparel for the workers and appropriate ventilation can minimize these

exposures.

967, 1258–1260

Gloves used for the task of sorting laundry should be of sufficient thickness to

minimize sharps injuries.

967

Employee safety personnel and industrial hygienists can help to determine

the appropriate glove choice.

4. Parameters of the Laundry Process

Fabrics, textiles, and clothing used in health-care settings are disinfected during laundering and

generally rendered free of vegetative pathogens (i.e., hygienically clean), but they are not sterile.

1273

Laundering cycles consist of flush, main wash, bleaching, rinsing, and souring.

1274

Cleaned wet

textiles, fabrics, and clothing are then dried, pressed as needed, and prepared (e.g., folded and packaged)

for distribution back to the facility. Clean linens provided by an off-site laundry must be packaged prior

to transport to prevent inadvertent contamination from dust and dirt during loading, delivery, and

unloading. Functional packaging of laundry can be achieved in several ways, including a) placing clean

linen in a hamper lined with a previously unused liner, which is then closed or covered; b) placing clean

linen in a properly cleaned cart and covering the cart with disposable material or a properly cleaned

reusable textile material that can be secured to the cart; and c) wrapping individual bundles of clean

101

textiles in plastic or other suitable material and sealing or taping the bundles.

The antimicrobial action of the laundering process results from a combination of mechanical, thermal,

and chemical factors.

1271, 1275, 1276

Dilution and agitation in water remove substantial quantities of

microorganisms. Soaps and detergents function to suspend soils and also exhibit some microbiocidal

properties. Hot water provides an effective means of destroying microorganisms.

1277

A temperature of

at least 160°F (71°C) for a minimum of 25 minutes is commonly recommended for hot-water washing.

Water of this temperature can be provided by steam jet or separate booster heater.

120

The use of

chlorine bleach assures an extra margin of safety.

1278, 1279

A total available chlorine residual of 50–150

ppm is usually achieved during the bleach cycle.

1277

Chlorine bleach becomes activated at water

temperatures of 135°F–145°F (57.2°C–62.7°C). The last of the series of rinse cycles is the addition of a

mild acid (i.e., sour) to neutralize any alkalinity in the water supply, soap, or detergent. The rapid shift

in pH from approximately 12 to 5 is an effective means to inactivate some microorganisms.

1247

Effective removal of residual alkali from fabrics is an important measure in reducing the risk for skin

reactions among patients.

Chlorine bleach is an economical, broad-spectrum chemical germicide that enhances the effectiveness

of the laundering process. Chlorine bleach is not, however, an appropriate laundry additive for all

fabrics. Traditionally, bleach was not recommended for laundering flame-retardant fabrics, linens, and

clothing because its use diminished the flame-retardant properties of the treated fabric.

1273

However,

some modern-day flame retardant fabrics can now tolerate chlorine bleach. Flame-retardant fabrics,

whether topically treated or inherently flame retardant, should be thoroughly rinsed during the rinse

cycles, because detergent residues are capable of supporting combustion. Chlorine alternatives (e.g.,

activated oxygen-based laundry detergents) provide added benefits for fabric and color safety in

addition to antimicrobial activity. Studies comparing the antimicrobial potencies of chlorine bleach and

oxygen-based bleach are needed. Oxygen-based bleach and detergents used in health-care settings

should be registered by EPA to ensure adequate disinfection of laundry. Health-care workers should

note the cleaning instructions of textiles, fabrics, drapes, and clothing to identify special laundering

requirements and appropriate hygienic cleaning options.

1278

Although hot-water washing is an effective laundry disinfection method, the cost can be substantial.

Laundries are typically the largest users of hot water in hospitals. They consume 50%–75% of the total

hot water,

1280

representing an average of 10%–15% of the energy used by a hospital. Several studies

have demonstrated that lower water temperatures of 71°F–77°F (22°C–25°C) can reduce microbial

contamination when the cycling of the washer, the wash detergent, and the amount of laundry additive

are carefully monitored and controlled.

1247, 1281–1285

Low-temperature laundry cycles rely heavily on the

presence of chlorine- or oxygen-activated bleach to reduce the levels of microbial contamination. The

selection of hot- or cold-water laundry cycles may be dictated by state health-care facility licensing

standards or by other regulation. Regardless of whether hot or cold water is used for washing, the

temperatures reached in drying and especially during ironing provide additional significant

microbiocidal action.

1247

Dryer temperatures and cycle times are dictated by the materials in the

fabrics. Man-made fibers (i.e., polyester and polyester blends) require shorter times and lower

temperatures.

After washing, cleaned and dried textiles, fabrics, and clothing are pressed, folded, and packaged for

transport, distribution, and storage by methods that ensure their cleanliness until use.

State regulations

and/or accrediting standards may dictate the procedures for this activity. Clean/sterile and contaminated

textiles should be transported from the laundry to the health-care facility in vehicles (e.g., trucks, vans,

and carts) that allow for separation of clean/sterile and contaminated items. Clean/sterile textiles and

contaminated textiles may be transported in the same vehicle, provided that the use of physical barriers

and/or space separation can be verified to be effective in protecting the clean/sterile items from

102

contamination. Clean, uncovered/unwrapped textiles stored in a clean location for short periods of time

(e.g., uncovered and used within a few hours) have not been demonstrated to contribute to increased

levels of health-care–acquired infection. Such textiles can be stored in convenient places for use during

the provision of care, provided that the textiles can be maintained dry and free from soil and body-

substance contamination.

In the absence of microbiologic standards for laundered textiles, no rationale exists for routine

microbiologic sampling of cleaned health-care textiles and fabrics.

1286

Sampling may be used as part of

an outbreak investigation if epidemiologic evidence suggests that textiles, fabrics, or clothing are a

suspected vehicle for disease transmission. Sampling techniques include aseptically macerating the

fabric into pieces and adding these to broth media or using contact plates (RODAC plates) for direct

surface sampling.

1271, 1286

When evaluating the disinfecting properties of the laundering process

specifically, placing pieces of fabric between two membrane filters may help to minimize the

contribution of the physical removal of microorganisms.

1287

Washing machines and dryers in residential-care settings are more likely to be consumer items rather

than the commercial, heavy-duty, large volume units typically found in hospitals and other institutional

health-care settings. Although all washing machines and dryers in health-care settings must be properly

maintained for performance according to the manufacturer’s instructions, questions have been raised

about the need to disinfect washers and dryers in residential-care settings. Disinfection of the tubs and

tumblers of these machines is unnecessary when proper laundry procedures are followed; these

procedures involve a) the physical removal of bulk solids (e.g., feces) before the wash/dry cycle and b)

proper use of temperature, detergent, and laundry additives. Infection has not been linked to laundry

procedures in residential-care facilities, even when consumer versions of detergents and laundry

additives are used.

5. Special Laundry Situations

Some textile items (e.g., surgical drapes and reusable gowns) must be sterilized before use and therefore

require steam autoclaving after laundering.

Although the American Academy of Pediatrics in previous

guidelines recommended autoclaving for linens in neonatal intensive care units (NICUs), studies on the

microbial quality of routinely cleaned NICU linen have not identified any increased risk for infection

among the neonates receiving care.

1288

Consequently, hygienically clean linens are suitable for use in

this setting.

997

The use of sterile linens in burn therapy units remains unresolved.

Coated or laminated fabrics are often used in the manufacture of PPE. When these items become

contaminated with blood or other body substances, the manufacturer’s instructions for decontamination

and cleaning take into account the compatibility of the rubber backing with the chemical germicides or

detergents used in the process. The directions for decontaminating these items should be followed as

indicated; the item should be discarded when the backing develops surface cracks.

Dry cleaning, a cleaning process that utilizes organic solvents (e.g., perchloroethylene) for soil removal,

is an alternative means of cleaning fabrics that might be damaged in conventional laundering and

detergent washing. Several studies, however, have shown that dry cleaning alone is relatively

ineffective in reducing the numbers of bacteria and viruses on contaminated linens;

1289, 1290

microbial

populations are significantly reduced only when dry-cleaned articles are heat pressed. Dry cleaning

should therefore not be considered a routine option for health-care facility laundry and should be

reserved for those circumstances in which fabrics can not be safely cleaned with water and detergent.

1291

103

6. Surgical Gowns, Drapes, and Disposable Fabrics

An issue of recent concern involves the use of disposable (i.e., single use) versus reusable (i.e., multiple

use) surgical attire and fabrics in health-care settings.

1292

Regardless of the material used to

manufacture gowns and drapes, these items must be resistant to liquid and microbial penetration.

7, 1293–

1297

Surgical gowns and drapes must be registered with FDA to demonstrate their safety and

effectiveness. Repellency and pore size of the fabric contribute to gown performance, but performance

capability can be influenced by the item’s design and construction.

1298, 1299

Reinforced gowns (i.e.,

gowns with double-layered fabric) generally are more resistant to liquid strike-through.

1300, 1301

Reinforced gowns may, however, be less comfortable. Guidelines for selection and use of barrier

materials for surgical gowns and drapes have been published.

1302

When selecting a barrier product,

repellency level and type of barrier should be compatible for the exposure expected.

967

However, data

are limited regarding the association between gown or drape characteristics and risk for surgical site

infections.

7, 1303

Health-care facilities must ensure optimal protection of patients and health-care

workers. Not all fabric items in health care lend themselves to single-use. Facilities exploring options

for gowns and drapes should consider the expense of disposable items and the impact on the facility’s

waste-management costs once these items are discarded. Costs associated with the use of durable goods

involve the fabric or textile items; staff expenses to collect, sort, clean, and package the laundry; and

energy costs to operate the laundry if on-site or the costs to contract with an outside service.

1304, 1305

7. Antimicrobial-Impregnated Articles and Consumer Items Bearing
Antimicrobial Labeling

Manufacturers are increasingly incorporating antibacterial or antimicrobial chemicals into consumer and

health-care items. Some consumer products bearing labels that indicate treatment with antimicrobial

chemicals have included pens, cutting boards, toys, household cleaners, hand lotions, cat litter, soaps,

cotton swabs, toothbrushes, and cosmetics. The “antibacterial” label on household cleaning products, in

particular, gives consumers the impression that the products perform “better” than comparable products

without this labeling, when in fact all household cleaners have antibacterial properties.

In the health-care setting, treated items may include children’s pajamas, mattresses, and bed linens with

label claims of antimicrobial properties. These claims require careful evaluation to determine whether

they pertain to the use of antimicrobial chemicals as preservatives for the fabric or other components or

whether they imply a health claim.

1306, 1307

No evidence is available to suggest that use of these

products will make consumers and patients healthier or prevent disease. No data support the use of

these items as part of a sound infection-control strategy, and therefore, the additional expense of

replacing a facility’s bedding and sheets with these treated products is unwarranted.

EPA has reaffirmed its position that manufacturers who make public health claims for articles

containing antimicrobial chemicals must provide evidence to support those claims as part of the

registration process.

1308

Current EPA regulations outlined in the Treated Articles Exemption of the

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) require manufacturers to register both the

antimicrobial chemical used in or on the product and the finished product itself if a public health claim

is maintained for the item. The exemption applies to the use of antimicrobial chemicals for the purpose

of preserving the integrity of the product’s raw material(s). The U.S. Federal Trade Commission (FTC)

is evaluating manufacturer advertising of products with antimicrobial claims.

1309

104

8. Standard Mattresses, Pillows, and Air-Fluidized Beds

Standard mattresses and pillows can become contaminated with body substances during patient care if

the integrity of the covers of these items is compromised. The practice of sticking needles into the

mattress should be avoided. A mattress cover is generally a fitted, protective material, the purpose of

which is to prevent the mattress from becoming contaminated with body fluids and substances. A linen

sheet placed on the mattress is not considered a mattress cover. Patches for tears and holes in mattress

covers do not provide an impermeable surface over the mattress. Mattress covers should be replaced

when torn; the mattress should be replaced if it is visibly stained. Wet mattresses, in particular, can be a

substantial environmental source of microorganisms. Infections and colonizations caused by

Acinetobacter

spp., MRSA, and

Pseudomonas aeruginosa

have been described, especially among burn

patients.

1310–1315

In these reports, the removal of wet mattresses was an effective infection-control

measure. Efforts were made to ensure that pads and covers were cleaned and disinfected between

patients using disinfectant products compatible with mattress-cover materials to ensure that these covers

remained impermeable to fluids.

1310–1314

Pillows and their covers should be easily cleanable, preferably

in a hot water laundry cycle.

1315

These should be laundered between patients or if contaminated with

body substances.

Air-fluidized beds are used for the care of patients immobilized for extended periods of time because of

therapy or injury (e.g., pain, decubitus ulcers, and burns).

1316

These specialized beds consist of a base

unit filled with microsphere beads fluidized by warm, dry air flowing upward from a diffuser located at

the bottom of the unit. A porous, polyester filter sheet separates the patient from direct contact with the

beads but allows body fluids to pass through to the beads. Moist beads aggregate into clumps which

settle to the bottom where they are removed as part of routine bed maintenance.

Because the beads become contaminated with the patient’s body substances, concerns have been raised

about the potential for these beds to serve as an environmental source of pathogens. Certain pathogens

(e.g.,

Enterococcus

spp.,

Serratia marcescens, Staphylococcus aureus

, and

Streptococcus fecalis

) have

been recovered either from the microsphere beads or the polyester sheet after cleaning.

1317, 1318

Reports

of cross-contamination of patients, however, are few.

1318

Nevertheless, routine maintenance and

between-patient decontamination procedures can minimize potential risks to patients. Regular removal

of bead clumps, coupled with the warm, dry air of the bed, can help to minimize bacterial growth in the

unit.

1319–1321

Beads are decontaminated between patients by high heat (113°F–194°F [45°C–90°C],

depending on the manufacturer’s specifications) for at least 1 hour; this procedure is particularly

important for the inactivation of

Enterococcus

spp. which are relatively resistant to heat.

1322, 1323

The

polyester filter sheet requires regular changing and thorough cleaning and disinfection, especially

between patients.

1317, 1318, 1322, 1323

Microbial contamination of the air space in the immediate vicinity of a properly maintained air-fluidized

bed is similar to that found in air around conventional bedding, despite the air flow out of the base unit

and around the patient.

1320, 1324, 1325

An operational air-fluidized bed can, however, interfere with proper

pressure differentials, especially in negative-pressure rooms;

1326

the effect varies with the location of

the bed relative to the room’s configuration and supply and exhaust vent locations. Use of an air-

fluidized bed in a negative-pressure room requires consultation with a facility engineer to determine

appropriate placement of the bed.

105

H. Animals in Health-Care Facilities

1. General Information

Animals in health-care facilities traditionally have been limited to laboratories and research areas.

However, their presence in patient-care areas is now more frequent, both in acute-care and long-term

care settings, prompting consideration for the potential transmission of zoonotic pathogens from animals

to humans in these settings. Although dogs and cats may be commonly encountered in health-care

settings, other animals (e.g., fish, birds, non-human primates, rabbits, rodents, and reptiles) also can be

present as research, resident, or service animals. These animals can serve as sources of zoonotic

pathogens that could potentially infect patients and health-care workers (Table 26).

1327–1340

Animals

potentially can serve as reservoirs for antibiotic-resistant microorganisms, which can be introduced to

the health-care setting while the animal is present. VRE have been isolated from both farm animals and

pets,

1341

and a cat in a geriatric care center was found to be colonized with MRSA.

1342

Table 26. Examples of diseases associated with zoonotic transmission*+

Infectious disease

Cats

Dogs

Fish

Birds Rabbits Reptiles§ Primates Rodents§

Virus

Lymphocytic choriomeningitis

Rabies

Bacteria

Campylobacteriosis

Capnocytophaga canimorsus

infection

Cat scratch disease (

Bartonella

henselae

)

Leptospirosis

Mycobacteriosis

Pasteurellosis

Plague

Psittacosis

Q fever (

Coxiella burnetti

)

Rat bite fever (

Spirrillum minus,

Streptobacillus monliformis

)

Salmonellosis

Tularemia

Yersiniosis

Parasites

Ancylostomiasis

Cryptosporidiosis

Giardiasis

Toxocariasis

Toxoplasmosis

Fungi

Blastomycosis

Dermatophytosis

* Material in this table is adapted from reference 1331 and used with permission of the publisher (Lippincott Williams and Wilkins).

+ This table does not include vectorborne diseases.

§ Reptiles include lizards, snakes, and turtles. Rodents include hamsters, mice, and rats.
¶ The

symbol indicates that the pathogen associated with the infection has been isolated from animals and is considered to pose potential

risk to humans.

106

Zoonoses can be transmitted from animals to humans either directly or indirectly via bites, scratches,

aerosols, ectoparasites, accidental ingestion, or contact with contaminated soil, food, water, or

unpasteurized milk.

1331, 1332, 1343–1345

Colonization and hand transferral of pathogens acquired from pets

in health-care workers’ homes represent potential sources and modes of transmission of zoonotic

pathogens in health-care settings. An outbreak of infections caused by a yeast (

Malassezia

pachydermatis

) among newborns was traced to transfer of the yeast from the hands of health-care

workers with pet dogs at home.

1346

In addition, an outbreak of ringworm in a NICU caused by

Microsporum canis

was associated with a nurse and her cat,

1347

and an outbreak of

Rhodococcus

(Gordona) bronchialis

sternal SSIs after coronary-artery bypass surgery was traced to a colonized nurse

whose dogs were culture-positive for the organism.

1348

In the latter outbreak, whether the dogs were

the sole source of the organism and whether other environmental reservoirs contributed to the outbreak

are unknown. Nonetheless, limited data indicate that outbreaks of infectious disease have occurred as a

result of contact with animals in areas housing immunocompetent patients. However, the low frequency

of outbreaks may result from a) the relatively limited presence of the animals in health-care facilities

and b) the immunocompetency of the patients involved in the encounters. Formal scientific studies to

evaluate potential risks of transmission of zoonoses in health-care settings outside of the laboratory are

lacking.

2. Animal-Assisted Activities, Animal-Assisted Therapy, and Resident
Animals

Animal-Assisted Activities (AAA) are those programs that enhance the patients’ quality of life. These

programs allow patients to visit animals in either a common, central location in the facility or in

individual patient rooms. A group session with the animals enhances opportunities for ambulatory

patients and facility residents to interact with caregivers, family members, and volunteers.

1349–1351

Alternatively, allowing the animals access to individual rooms provides the same opportunity to non-

ambulatory patients and patients for whom privacy or dignity issues are a consideration. The decision

to allow this access to patients’ rooms should be made on a case-by-case basis, with the consultation and

consent of the attending physician and nursing staff.

Animal-Assisted Therapy (AAT) is a goal-directed intervention that incorporates an animal into the

treatment process provided by a credentialed therapist.

1330, 1331

The concept for AAT arose from the

observation that some patients with pets at home recover from surgical and medical procedures more

rapidly than patients without pets.

1352, 1353

Contact with animals is considered beneficial for enhancing

wellness in certain patient populations (e.g., children, the elderly, and extended-care hospitalized

patients).

1349, 1354–1357

However, evidence supporting this benefit is largely derived from anecdotal

reports and observations of patient/animal interactions.

1357–1359

Guidelines for establishing AAT

programs are available for facilities considering this option.

1360

The incorporation of non-human primates into an AAA or AAT program is not encouraged because of

concerns regarding potential disease transmission from and unpredictable behavior of these animals.

1361,

1362

Animals participating in either AAA or AAT sessions should be in good health and up-to-date with

recommended immunizations and prophylactic medications (e.g., heartworm prevention) as determined

by a licensed veterinarian based on local needs and recommendations. Regular re-evaluation of the

animal’s health and behavior status is essential.

1360

Animals should be routinely screened for enteric

parasites and/or have evidence of a recently completed antihelminthic regimen.

1363

They should also be

free of ectoparasites (e.g., fleas and ticks) and should have no sutures, open wounds, or obvious

dermatologic lesions that could be associated with bacterial, fungal, or viral infections or parasitic

infestations. Incorporating young animals (i.e., those aged <1 year) into these programs is not

encouraged because of issues regarding unpredictable behavior and elimination control. Additionally,

107

the immune systems of very young puppies and kittens is not completely developed, thereby placing the

health of these animals at risk. Animals should be clean and well-groomed. The visits must be

supervised by persons who know the animals and their behavior. Animal handlers should be trained in

these activities and receive site-specific orientation to ensure that they work efficiently with the staff in

the specific health-care environment.

1360

Additionally, animal handlers should be in good health.

1360

The most important infection-control measure to prevent potential disease transmission is strict

enforcement of hand-hygiene measures (e.g., using either soap and water or an alcohol-based hand rub)

for all patients, staff, and residents after handling the animals.

1355, 1364

Care should also be taken to

avoid direct contact with animal urine or feces. Clean-up of these substances from environmental

surfaces requires gloves and the use of leak-resistant plastic bags to discard absorbent material used in

the process.

The area must be cleaned after visits according to standard cleaning procedures.

The American Academy of Allergy, Asthma, and Immunology estimates that dog or cat allergies occur

in approximately 15% of the population.

1365

Minimizing contact with animal saliva, dander, and/or

urine helps to mitigate allergic responses.

1365–1367

Some facilities may not allow animal visitation for

patients with a) underlying asthma, b) known allergies to cat or dog hair, c) respiratory allergies of

unknown etiology, and d) immunosuppressive disorders. Hair shedding can be minimized by processes

that remove dead hair (e.g., grooming) and that prevent the shedding of dead hair (e.g., therapy capes

for dogs). Allergens can be minimized by bathing therapy animals within 24 hours of a visit.

1333, 1368

Animal therapists and handlers must take precautions to prevent animal bites. Common pathogens

associated with animal bites include

Capnocytophaga canimorsus, Pasteurella

spp.,

Staphylococcus

spp., and

Streptococcus

spp. Selecting well-behaved and well-trained animals for these programs

greatly decreases the incidence of bites. Rodents, exotic species, wild/domestic animals (i.e., wolf-dog

hybrids), and wild animals whose behavior is unpredictable should be excluded from AAA or AAT

programs. A well-trained animal handler should be able to recognize stress in the animal and to

determine when to terminate a session to minimize risk. When an animal bites a person during AAA or

AAT, the animal is to be permanently removed from the program. If a bite does occur, the wound must

be cleansed immediately and monitored for subsequent infection. Most infections can be treated with

antibiotics, and antibiotics often are prescribed prophylactically in these situations.

The health-care facility’s infection-control staff should participate actively in planning for and

coordinating AAA and AAT sessions. Many facilities do not offer AAA or AAT programs for severely

immunocompromised patients (e.g., HSCT patients and patients on corticosteroid therapy).

1339

The

question of whether family pets or companion animals can visit terminally-ill HSCT patients or other

severely immunosuppressed patients is best handled on a case-by-case basis, although animals should

not be brought into the HSCT unit or any other unit housing severely immunosuppressed patients. An

in-depth discussion of this issue is presented elsewhere.

1366

Immunocompromised patients who have been discharged from a health-care facility may be at higher

risk for acquiring some pet-related zoonoses. Although guidelines have been developed to minimize the

risk of disease transmission to HIV-infected patients,

these recommendations may be applicable for

patients with other immunosuppressive disorders. In addition to handwashing or hand hygiene, these

recommendations include avoiding contact with a) animal feces and soiled litter box materials, b)

animals with diarrhea, c) very young animals (i.e., dogs <6 months of age and cats <1 year of age), and

d) exotic animals and reptiles.

Pets or companion animals with diarrhea should receive veterinary care

to resolve their condition.

Many health-care facilities are adopting more home-like environments for residential-care or extended-

stay patients in acute-care settings, and resident animals are one element of this approach.

1369

One

108

concept, the “Eden Alternative,” incorporates children, plants, and animals (e.g., dogs, cats, fish, birds,

rabbits, and rodents) into the daily care setting.

1370, 1371

The concept of working with resident animals

has not been scientifically evaluated. Several issues beyond the benefits of therapy must be considered

before embarking on such a program, including a) whether the animals will come into direct contact

with patients and/or be allowed to roam freely in the facility; b) how the staff will provide care for the

animals; c) the management of patients’ or residents’ allergies, asthma, and phobias; d) precautionary

measures to prevent bites and scratches; and e) measures to properly manage the disposal of animal

feces and urine, thereby preventing environmental contamination by zoonotic microorganisms (e.g.,

Toxoplasma

spp.

, Toxocara

spp., and

Ancylostoma

spp.).

1372, 1373

Few data document a link between

health-care–acquired infection rates and frequency of cleaning fish tanks or rodent cages. Skin

infections caused by

Mycobacterium marinum

have been described among persons who have fish

aquariums at home.

1374, 1375

Nevertheless, immunocompromised patients should avoid direct contact

with fish tanks and cages and the aerosols that these items produce. Further, fish tanks should be kept

clean on a regular basis as determined by facility policy, and this task should be performed by gloved

staff members who are not responsible for patient care. The use of the infection-control risk assessment

can help determine whether a fish tank poses a risk for patient or resident safety and health in these

situations. No evidence, however, links the incidence of health-care–acquired infections among

immunocompetent patients or residents with the presence of a properly cleaned and maintained fish

tank, even in dining areas. As a general preventive measure, resident animal programs are advised to

restrict animals from a) food preparation kitchens, b) laundries, c) central sterile supply and any storage

areas for clean supplies, and d) medication preparation areas. Resident-animal programs in acute-care

facilities should not allow the animals into the isolation areas, protective environments, ORs, or any area

where immunocompromised patients are housed. Patients and staff routinely should wash their hands or

use waterless, alcohol-based hand-hygiene products after contact with animals.

3. Service Animals

Although this section provides an overview about service animals in health-care settings, it cannot

address every situation or question that may arise (see Appendix E - Information Resources). A service

animal is any animal individually trained to do work or perform tasks for the benefit of a person with a

disability.

1366, 1376

A service animal is not considered a pet but rather an animal trained to provide

assistance to a person because of a disability. Title III of the “Americans with Disabilities Act” (ADA)

of 1990 mandates that persons with disabilities accompanied by service animals be allowed access with

their service animals into places of public accommodation, including restaurants, public transportation,

schools, and health-care facilities.

1366, 1376

In health-care facilities, a person with a disability requiring a

service animal may be an employee, a visitor, or a patient.

An overview of the subject of service animals and their presence in health-care facilities has been

published.

1366

No evidence suggests that animals pose a more significant risk of transmitting infection

than people; therefore, service animals should not be excluded from such areas, unless an individual

patient’s situation or a particular animal poses greater risk that cannot be mitigated through reasonable

measures. If health-care personnel, visitors, and patients are permitted to enter care areas (e.g., in-

patient rooms, some ICUs, and public areas) without taking additional precautions to prevent

transmission of infectious agents (e.g., donning gloves, gowns, or masks), a clean, healthy, well-

behaved service animal should be allowed access with its handler.

1366

Similarly, if

immunocompromised patients are able to receive visitors without using protective garments or

equipment, an exclusion of service animals from this area would not be justified.

1366

Because health-care facilities are covered by the ADA or the Rehabilitation Act, a person with a

disability may be accompanied by a service animal within the facility unless the animal’s presence or

109

behavior creates a fundamental alteration in the nature of a facility’s services in a particular area or a

direct threat to other persons in a particular area.

1366

A “direct threat” is defined as a significant risk to

the health or safety of others that cannot be mitigated or eliminated by modifying policies, practices, or

procedures.

1376

The determination that a service animal poses a direct threat in any particular health-

care setting must be based on an individualized assessment of the service animal, the patient, and the

health-care situation. When evaluating risk in such situations, health-care personnel should consider the

nature of the risk (including duration and severity); the probability that injury will occur; and whether

reasonable modifications of policies, practices, or procedures will mitigate the risk (J. Wodatch, U.S.

Department of Justice, 2000). The person with a disability should contribute to the risk-assessment

process as part of a pre-procedure health-care provider/patient conference.

Excluding a service animal from an OR or similar special care areas (e.g., burn units, some ICUs, PE

units, and any other area containing equipment critical for life support) is appropriate if these areas are

considered to have “restricted access” with regards to the general public. General infection-control

measures that dictate such limited access include a) the area is required to meet environmental criteria to

minimize the risk of disease transmission, b) strict attention to hand hygiene and absence of

dermatologic conditions, and c) barrier protective measures [e.g., using gloves, wearing gowns and

masks] are indicated for persons in the affected space. No infection-control measures regarding the use

of barrier precautions could be reasonably imposed on the service animal. Excluding a service animal

that becomes threatening because of a perceived danger to its handler during treatment also is

appropriate; however, exclusion of such an animal must be based on the actual behavior of the particular

animal, not on speculation about how the animal might behave.

Another issue regarding service animals is whether to permit persons with disabilities to be

accompanied by their service animals during all phases of their stay in the health-care facility. Health-

care personnel should discuss all aspects of anticipatory care with the patient who uses a service animal.

Health-care personnel may not exclude a service animal because health-care staff may be able to

perform the same services that the service animal does (e.g., retrieving dropped items and guiding an

otherwise ambulatory person to the restroom). Similarly, health-care personnel can not exclude service

animals because the health-care staff perceive a lack of need for the service animal during the person’s

stay in the health-care facility. A person with a disability is entitled to independent access (i.e., to be

accompanied by a service animal unless the animal poses a direct threat or a fundamental alteration in

the nature of services); “need” for the animal is not a valid factor in either analysis. For some forms of

care (e.g., ambulation as physical therapy following total hip replacement or knee replacement), the

service animal should not be used in place of a credentialed health-care worker who directly provides

therapy. However, service animals need not be restricted from being in the presence of its handler

during this time; in addition, rehabilitation and discharge planning should incorporate the patient’s

future use of the animal. The health-care personnel and the patient with a disability should discuss both

the possible need for the service animal to be separated from its handler for a period of time during non-

emergency care and an alternate plan of care for the service animal in the event the patient is unable or

unwilling to provide that care. This plan might include family members taking the animal out of the

facility several times a day for exercise and elimination, the animal staying with relatives, or boarding

off-site. Care of the service animal, however, remains the obligation of the person with the disability,

not the health-care staff.

Although animals potentially carry zoonotic pathogens transmissible to man, the risk is minimal with a

healthy, clean, vaccinated, well-behaved, and well-trained service animal, the most common of which

are dogs and cats. No reports have been published regarding infectious disease that affects humans

originating in service dogs. Standard cleaning procedures are sufficient following occupation of an area

by a service animal.

1366

Clean-up of spills of animal urine, feces, or other body substances can be

accomplished with blood/body substance procedures outlined in the Environmental Services section of

110

this guideline. No special bathing procedures are required prior to a service animal accompanying its

handler into a health-care facility.

Providing access to exotic animals (e.g., reptiles and non-human primates) that are used as service

animals is problematic. Concerns about these animals are discussed in two published reviews.

1331, 1366

Because some of these animals exhibit high-risk behaviors that may increase the potential for zoonotic

disease transmission (e.g., herpes B infection), providing health-care facility access to nonhuman

primates used as service animals is discouraged, especially if these animals might come into contact

with the general public.

1361, 1362

Health-care administrators should consult the Americans with

Disabilities Act for guidance when developing policies about service animals in their facilities.

1366, 1376

Requiring documentation for access of a service animal to an area generally accessible to the public

would impose a burden on a person with a disability. When health-care workers are not certain that an

animal is a service animal, they may ask the person who has the animal if it is a service animal required

because of a disability; however, no certification or other documentation of service animal status can be

required.

1377

4. Animals as Patients in Human Health-Care Facilities

The potential for direct and indirect transmission of zoonoses must be considered when rooms and

equipment in human health-care facilities are used for the medical or surgical treatment or diagnosis of

animals.

1378

Inquiries should be made to veterinary medical professionals to determine an appropriate

facility and equipment to care for an animal.

The central issue associated with providing medical or surgical care to animals in human health-care

facilities is whether cross-contamination occurs between the animal patient and the human health-care

workers and/or human patients. The fundamental principles of infection control and aseptic practice

should differ only minimally, if at all, between veterinary medicine and human medicine. Health-care–

associated infections can and have occurred in both patients and workers in veterinary medical facilities

when lapses in infection-control procedures are evident.

1379–1384

Further, veterinary patients can be at

risk for acquiring infection from veterinary health-care workers if proper precautions are not taken.

1385

The issue of providing care to veterinary patients in human health-care facilities can be divided into the

following three areas of infection-control concerns: a) whether the room/area used for animal care can

be made safe for human patients, b) whether the medical/surgical instruments used on animals can be

subsequently used on human patients, and c) which disinfecting or sterilizing procedures need to be

done for these purposes. Studies addressing these concerns are lacking. However, with respect to

disinfection or sterilization in veterinary settings, only minimal evidence suggests that zoonotic

microbial pathogens are unusually resistant to inactivation by chemical or physical agents (with the

exception of prions). Ample evidence supports the contrary observation (i.e., that pathogens from

human- and animal sources are similar in their relative instrinsic resistance to inactivation).

1386–1391

Further, no evidence suggests that zoonotic pathogens behave differently from human pathogens with

respect to ventilation. Despite this knowledge, an aesthetic and sociologic perception that animal care

must remain separate from human care persists. Health-care facilities, however, are increasingly faced

with requests from the veterinary medical community for access to human health-care facilities for

reasons that are largely economical (e.g., costs of acquiring sophisticated diagnostic technology and

complex medical instruments). If hospital guidelines allow treatment of animals, alternate veterinary

resources (including veterinary hospitals, clinics, and universities) should be exhausted before using

human health-care settings. Additionally, the hospital’s public/media relations should be notified of the

situation. The goal is to develop policies and procedures to proactively and positively discuss and

111

disclose this activity to the general public.

An infection-control risk assessment (ICRA) must be undertaken to evaluate the circumstances specific

to providing care to animals in a human health-care facility. Individual hospital policies and guidelines

should be reviewed before any animal treatment is considered in such facilities. Animals treated in

human health-care facilities should be under the direct care and supervision of a licensed veterinarian;

they also should be free of known infectious diseases, ectoparasites, and other external contaminants

(e.g., soil, urine, and feces). Measures should be taken to avoid treating animals with a known or

suspected zoonotic disease in a human health-care setting (e.g., lambs being treated for Q fever).

If human health-care facilities must be used for animal treatment or diagnostics, the following general

infection-control actions are suggested: a) whenever possible, the use of ORs or other rooms used for

invasive procedures should be avoided [e.g., cardiac catheterization labs and invasive nuclear medicine

areas]; b) when all other space options are exhausted and use of the aforementioned rooms is

unavoidable, the procedure should be scheduled late in the day as the last procedure for that particular

area such that patients are not present in the department/unit/area; c) environmental surfaces should be

thoroughly cleaned and disinfected using procedures discussed in the Environmental Services portion of

this guideline after the animal is removed from the care area; d) sufficient time should be allowed for

ACH to help prevent allergic reactions by human patients [Table B.1. in Appendix B]; e) only

disposable equipment or equipment that can be thoroughly and easily cleaned, disinfected, or sterilized

should be used; f) when medical or surgical instruments, especially those invasive instruments that are

difficult to clean [e.g., endoscopes], are used on animals, these instruments should be reserved for future

use only on animals; and g) standard precautions should be followed.

5. Research Animals in Health-Care Facilities

The risk of acquiring a zoonotic infection from research animals has decreased in recent years because

many small laboratory animals (e.g., mice, rats, and rabbits) come from quality stock and have defined

microbiologic profiles.

1392

Larger animals (e.g., nonhuman primates) are still obtained frequently from

the wild and may harbor pathogens transmissible to humans. Primates, in particular, benefit from

vaccinations to protect their health during the research period provided the vaccination does not

interfere with the study of the particular agent. Animals serving as models for human disease studies

pose some risk for transmission of infection to laboratory or health-care workers from percutaneous or

mucosal exposure. Exposures can occur either through a) direct contact with an infected animal or its

body substances and secretions or b) indirect contact with infectious material on equipment,

instruments, surfaces, or supplies.

1392

Uncontained aerosols generated during laboratory procedures can

also transmit infection.

Infection-control measures to prevent transmission of zoonotic infections from research animals are

largely derived from the following basic laboratory safety principles: a) purchasing pathogen-free

animals, b) quarantining incoming animals to detect any zoonotic pathogens, c) treating infected

animals or removing them from the facility, d) vaccinating animal carriers and high-risk contacts if

possible, e) using specialized containment caging or facilities, and f) using protective clothing and

equipment [e.g., gloves, face shields, gowns, and masks].

1392

An excellent resource for detailed

discussion of these safety measures has been published.

1013

The animal research unit within a health-care facility should be engineered to provide a) adequate

containment of animals and pathogens; b) daily decontamination and transport of equipment and waste;

c) proper ventilation and air filtration, which prevents recirculation of the air in the unit to other areas of

the facility; and d) negative air pressure in the animal rooms relative to the corridors. To ensure

112

adequate security and containment, no through traffic to other areas of the health-care facility should

flow through this unit; access should be restricted to animal-care staff, researchers, environmental

services, maintenance, and security personnel.

Occupational health programs for animal-care staff, researchers, and maintenance staff should take into

consideration the animals’ natural pathogens and research pathogens. Components of such programs

include a) prophylactic vaccines, b) TB skin testing when primates are used, c) baseline serums, and d)

hearing and respiratory testing. Work practices, PPE, and engineering controls specific for each of the

four animal biosafety levels have been published.

1013, 1393

The facility’s occupational or employee

health clinic should be aware of the appropriate post-exposure procedures involving zoonoses and have

available the appropriate post-exposure biologicals and medications.

Animal-research-area staff should also develop standard operating procedures for a) daily animal

husbandry [e.g., protection of the employee while facilitating animal welfare]; b) pathogen containment

and decontamination; c) management, cleaning, disinfecting and/or sterilizing equipment and

instruments; and d) employee training for laboratory safety and safety procedures specific to animal

research worksites.

1013

The federal Animal Welfare Act of 1966 and its amendments serve as the

regulatory basis for ensuring animal welfare in research.

1394, 1395

I. Regulated Medical Waste

1. Epidemiology

No epidemiologic evidence suggests that most of the solid- or liquid wastes from hospitals, other health-

care facilities, or clinical/research laboratories is any more infective than residential waste. Several

studies have compared the microbial load and the diversity of microorganisms in residential wastes and

wastes obtained from a variety of health-care settings.

1399–1402

Although hospital wastes had a greater

number of different bacterial species compared with residential waste, wastes from residences were

more heavily contaminated.

1397, 1398

Moreover, no epidemiologic evidence suggests that traditional

waste-disposal practices of health-care facilities (whereby clinical and microbiological wastes were

decontaminated on site before leaving the facility) have caused disease in either the health-care setting

or the general community.

1400, 1401

This statement excludes, however, sharps injuries sustained during

or immediately after the delivery of patient care before the sharp is “discarded.” Therefore, identifying

wastes for which handling and disposal precautions are indicated is largely a matter of judgment about

the relative risk of disease transmission, because no reasonable standards on which to base these

determinations have been developed. Aesthetic and emotional considerations (originating during the

early years of the HIV epidemic) have, however, figured into the development of treatment and disposal

policies, particularly for pathology and anatomy wastes and sharps.

1402–1405

Public concerns have

resulted in the promulgation of federal, state, and local rules and regulations regarding medical waste

management and disposal.

1406–1414

2. Categories of Medical Waste

Precisely defining medical waste on the basis of quantity and type of etiologic agents present is virtually

impossible. The most practical approach to medical waste management is to identify wastes that

represent a sufficient potential risk of causing infection during handling and disposal and for which

some precautions likely are prudent.

Health-care facility medical wastes targeted for handling and

disposal precautions include microbiology laboratory waste (e.g., microbiologic cultures and stocks of

microorganisms), pathology and anatomy waste, blood specimens from clinics and laboratories, blood

113

products, and other body-fluid specimens.

Moreover, the risk of either injury or infection from certain

sharp items (e.g., needles and scalpel blades) contaminated with blood also must be considered.

Although any item that has had contact with blood, exudates, or secretions may be potentially infective,

treating all such waste as infective is neither practical nor necessary. Federal, state, and local guidelines

and regulations specify the categories of medical waste that are subject to regulation and outline the

requirements associated with treatment and disposal. The categorization of these wastes has generated

the term “regulated medical waste.” This term emphasizes the role of regulation in defining the actual

material and as an alternative to “infectious waste,” given the lack of evidence of this type of waste’s

infectivity. State regulations also address the degree or amount of contamination (e.g., blood-soaked

gauze) that defines the discarded item as a regulated medical waste. The EPA’s

Manual for Infectious

Waste Management

identifies and categorizes other specific types of waste generated in health-care

facilities with research laboratories that also require handling precautions.

1406

3. Management of Regulated Medical Waste in Health-Care Facilities

Medical wastes require careful disposal and containment before collection and consolidation for

treatment. OSHA has dictated initial measures for discarding regulated medical-waste items. These

measures are designed to protect the workers who generate medical wastes and who manage the wastes

from point of generation to disposal.

967

A single, leak-resistant biohazard bag is usually adequate for

containment of regulated medical wastes, provided the bag is sturdy and the waste can be discarded

without contaminating the bag’s exterior. The contamination or puncturing of the bag requires

placement into a second biohazard bag. All bags should be securely closed for disposal. Puncture-

resistant containers located at the point of use (e.g., sharps containers) are used as containment for

discarded slides or tubes with small amounts of blood, scalpel blades, needles and syringes, and unused

sterile sharps.

967

To prevent needlestick injuries, needles and other contaminated sharps should not be

recapped, purposefully bent, or broken by hand. CDC has published general guidelines for handling

sharps.

6, 1415

Health-care facilities may need additional precautions to prevent the production of

aerosols during the handling of blood-contaminated items for certain rare diseases or conditions (e.g.,

Lassa fever and Ebola virus infection).

203

Transporting and storing regulated medical wastes within the health-care facility prior to terminal

treatment is often necessary. Both federal and state regulations address the safe transport and storage of

on- and off-site regulated medical wastes.

1406–1408

Health-care facilities are instructed to dispose

medical wastes regularly to avoid accumulation. Medical wastes requiring storage should be kept in

labeled, leak-proof, puncture-resistant containers under conditions that minimize or prevent foul odors.

The storage area should be well ventilated and be inaccessible to pests. Any facility that generates

regulated medical wastes should have a regulated medical waste management plan to ensure health and

environmental safety as per federal, state, and local regulations.

4. Treatment of Regulated Medical Waste

Regulated medical wastes are treated or decontaminated to reduce the microbial load in or on the waste

and to render the by-products safe for further handling and disposal. From a microbiologic standpoint,

waste need not be rendered “sterile” because the treated waste will not be deposited in a sterile site. In

addition, waste need not be subjected to the same reprocessing standards as are surgical instruments.

Historically, treatment methods involved steam-sterilization (i.e., autoclaving), incineration, or

interment (for anatomy wastes). Alternative treatment methods developed in recent years include

chemical disinfection, grinding/shredding/disinfection methods, energy-based technologies (e.g.,

microwave or radiowave treatments), and disinfection/encapsulation methods.

1409

State medical waste

regulations specify appropriate treatment methods for each category of regulated medical waste.

114

Of all the categories comprising regulated medical waste, microbiologic wastes (e.g., untreated cultures,

stocks, and amplified microbial populations) pose the greatest potential for infectious disease

transmission, and sharps pose the greatest risk for injuries. Untreated stocks and cultures of

microorganisms are subsets of the clinical laboratory or microbiologic waste stream. If the

microorganism must be grown and amplified in culture to high concentration to permit work with the

specimen, this item should be considered for on-site decontamination, preferably within the laboratory

unit. Historically, this was accomplished effectively by either autoclaving (steam sterilization) or

incineration. If steam sterilization in the health-care facility is used for waste treatment, exposure of the

waste for up to 90 minutes at 250°F (121°C) in a autoclave (depending on the size of the load and type

container) may be necessary to ensure an adequate decontamination cycle.

1416–1418

After steam

sterilization, the residue can be safely handled and discarded with all other nonhazardous solid waste in

accordance with state solid-waste disposal regulations. On-site incineration is another treatment option

for microbiologic, pathologic, and anatomic waste, provided the incinerator is engineered to burn these

wastes completely and stay within EPA emissions standards.

1410

Improper incineration of waste with

high moisture and low energy content (e.g., pathology waste) can lead to emission problems. State

medical-waste regulatory programs identify acceptable methods for inactivating amplified stocks and

cultures of microorganisms, some of which may employ technology rather than steam sterilization or

incineration.

Concerns have been raised about the ability of modern health-care facilities to inactivate microbiologic

wastes on-site, given that many of these institutions have decommissioned their laboratory autoclaves.

Current laboratory guidelines for working with infectious microorganisms at biosafety level (BSL) 3

recommend that all laboratory waste be decontaminated before disposal by an approved method,

preferably within the laboratory.

1013

These same guidelines recommend that all materials removed

from a BSL 4 laboratory (unless they are biological materials that are to remain viable) are to be

decontaminated before they leave the laboratory.

1013

Recent federal regulations for laboratories that

handle certain biological agents known as “select agents” (i.e., those that have the potential to pose a

severe threat to public health and safety) require these agents (and those obtained from a clinical

specimen intended for diagnostic, reference, or verification purposes) to be destroyed on-site before

disposal.

1412

Although recommendations for laboratory waste disposal from BSL 1 or 2 laboratories

(e.g., most health-care clinical and diagnostic laboratories) allow for these materials to be

decontaminated off-site before disposal, on-site decontamination by a known effective method is

preferred to reduce the potential of exposure during the handling of infectious material.

A recent outbreak of TB among workers in a regional medical-waste treatment facility in the United

States demonstrated the hazards associated with aerosolized microbiologic wastes.

1419, 1420

The facility

received diagnostic cultures of

Mycobacterium tuberculosis

from several different health-care facilities

before these cultures were chemically disinfected; this facility treated this waste with a

grinding/shredding process that generated aerosols from the material.

1419, 1420

Several operational

deficiencies facilitated the release of aerosols and exposed workers to airborne

M. tuberculosis

. Among

the suggested control measures was that health-care facilities perform on-site decontamination of

laboratory waste containing live cultures of microorganisms before release of the waste to a waste

management company.

1419, 1420

This measure is supported by recommendations found in the CDC/NIH

guideline for laboratory workers.

1013

This outbreak demonstrates the need to avoid the use of any

medical-waste treatment method or technology that can aerosolize pathogens from live cultures and

stocks (especially those of airborne microorganisms) unless aerosols can be effectively contained and

workers can be equipped with proper PPE.

1419–1421

Safe laboratory practices, including those addressing

waste management, have been published.

1013, 1422

In an era when local, state, and federal health-care facilities and laboratories are developing bioterrorism

115

response strategies and capabilities, the need to reinstate in-laboratory capacity to destroy cultures and

stocks of microorganisms becomes a relevant issue.

1423

Recent federal regulations require health-care

facility laboratories to maintain the capability of destroying discarded cultures and stocks on-site if these

laboratories isolate from a clinical specimen any microorganism or toxin identified as a “select agent”

from a clinical specimen (Table 27).

1412, 1413

As an alternative, isolated cultures of select agents can be

transferred to a facility registered to accept these agents in accordance with federal regulations.

1412

State medical waste regulations can, however, complicate or completely prevent this transfer if these

cultures are determined to be medical waste, because most states regulate the inter-facility transfer of

untreated medical wastes.

Table 27. Microorganisms and biologicals identified as select agents*+

HHS Non-overlap select agents and toxins (42 CFR Part 73 §73.4)

Viruses

Crimean-Congo hemorrhagic fever virus; Ebola viruses; Cercopithecine herpesvirus 1 (herpes B

virus); Lassa fever virus; Marburg virus; monkeypox virus; South American hemorrhagic fever

viruses (Junin, Machupo, Sabia, Flexal, Guanarito); tick-borne encephalitis complex (flavi)

viruses (Central European tick-borne encephalitis, Far Eastern tick-borne encephalitis [Russian

spring and summer encephalitis, Kyasnaur Forest disease, Omsk hemorrhagic fever]); variola

major virus (smallpox virus); and variola minor virus (alastrim)

Exclusions¶

Vaccine strain of Junin virus (Candid. #1)

Bacteria

Rickettsia prowazekii, R. rickettsii, Yersinia pestis

Fungi

Coccidioides posadasii

Toxins

Abrin; conotoxins; diacetoxyscirpenol; ricin; saxitoxin; Shiga-like ribosome inactivating

proteins; tetrodotoxin

Exclusions¶

The following toxins (in purified form or in combinations of pure and impure forms) if the

aggregate amount under the control of a principal investigator does not, at any time, exceed the

amount specified: 100 mg of abrin; 100 mg of conotoxins; 1,000 mg of diacetoxyscirpenol; 100

mg of ricin; 100 mg of saxitoxin; 100 mg of Shiga-like ribosome inactivating proteins; or 100

mg of tetrodotoxin

Genetic elements,

recombinant nucleic

acids, and recombinant

organisms¶

• Select agent viral nucleic acids (synthetic or naturally-derived, contiguous or fragmented, in

host chromosomes or in expression vectors) that can encode infectious and/or replication

competent forms of any of the select agent viruses;

• Nucleic acids (synthetic or naturally-derived) that encode for the functional form(s) of any of

the toxins listed in this table if the nucleic acids: a) are in a vector or host chromosome;

b) can be expressed

in vivo

in vitro

; or c) are in a vector or host chromosome and can be

expressed

in vivo

in vitro

;

• Viruses, bacteria, fungi, and toxins listed in this table that have been genetically modified.

High consequence livestock pathogens and toxins/select agents (overlap agents) (42 CFR Part 73 §73.5 and
USDA regulation 9 CFR Part 121)

Viruses

Eastern equine encephalitis virus; Nipah and Hendra complex viruses; Rift Valley fever virus;

Venezuelan equine encephalitis virus

Exclusions¶

MP-12 vaccine strain of Rift Valley fever virus; TC-83 vaccine strain of Venezuelan equine

encephalitis virus

Bacteria

Bacillus anthracis; Brucella abortus, B. melitensis, B. suis; Burkholderia mallei

(formerly

Pseudomonas mallei

B. pseudomallei

(formerly

P. pseudomallei

); botulinum neurotoxin-

producing species of

Clostridium; Coxiella burnetii; Francisella tularensis

Fungi

Coccidioides immitis

Toxins

Botulinum neurotoxins;

Clostridium perfringens

epsilon toxin; Shigatoxin; staphylococcal

enterotoxins; T-2 toxin

Exclusions¶

The following toxins (in purified form or in combinations of pure and impure forms) if the

aggregate amount under the control of a principal investigator does not, at any time, exceed the

amount specified: 0.5 mg of botulinum neurotoxins; 100 mg of

Clostridium perfringens

epsilon

toxin; 100 mg of Shigatoxin; 5 mg of staphylococcal enterotoxins; or 1,000 mg of T-2 toxin

116

High consequence livestock pathogens and toxins/select agents (overlap agents) (42 CFR Part 73 §73.5 and
USDA regulation 9 CFR Part 121) (continued)

Genetic elements,

recombinant nucleic

acids, and recombinant

organisms¶

• Select agent viral nuclei acids (synthetic or naturally derived, contiguous or fragmented, in

host chromosomes or in expression vectors) thatcan encode infectious and/or replication

competent forms of any of the select agent viruses;

• Nucleic acids (synthetic or naturally derived) that encode for the functional form(s) of any of

the toxins listed in this table if the nucleic acids: a) are in a vector or host chromosome;

b) can be expressed

in vivo

in vitro

; or c) are in a vector or host chromosome and can be

expressed

in vivo

in vitro

;

• Viruses, bacteria, fungi, and toxins listed in this table that have been genetically modified

* Material in this table is compiled from references 1412, 1413, and 1424. Reference 1424 also contains lists of select agents that include

plant pathogens and pathogens affecting livestock.

+ 42 CFR 73 §§73.4 and 73.5 do not include any select agent or toxin that is in its naturally-occurring environment, provided it has not been

intentionally introduced, cultivated, collected, or otherwise extracted from its natural source. These sections also do not include non-viable

select agent organisms or nonfunctional toxins. This list of select agents is current as of 3 October 2003 and is subject to change pending

the final adoption of 42 CFR Part 73.

¶ These table entries are listed in reference 1412 and 1413, but were not included in reference 1424.

5. Discharging Blood, Fluids to Sanitary Sewers or Septic Tanks

The contents of all vessels that contain more than a few milliliters of blood remaining after laboratory

procedures, suction fluids, or bulk blood can either be inactivated in accordance with state-approved

treatment technologies or carefully poured down a utility sink drain or toilet.

1414

State regulations may

dictate the maximum volume allowable for discharge of blood/body fluids to the sanitary sewer. No

evidence indicates that bloodborne diseases have been transmitted from contact with raw or treated

sewage. Many bloodborne pathogens, particularly bloodborne viruses, are not stable in the environment

for long periods of time;

1425, 1426

therefore, the discharge of small quantities of blood and other body

fluids to the sanitary sewer is considered a safe method of disposing of these waste materials.

1414

The

following factors increase the likelihood that bloodborne pathogens will be inactivated in the disposal

process: a) dilution of the discharged materials with water; b) inactivation of pathogens resulting from

exposure to cleaning chemicals, disinfectants, and other chemicals in raw sewage; and c) effectiveness

of sewage treatment in inactivating any residual bloodborne pathogens that reach the treatment facility.

Small amounts of blood and other body fluids should not affect the functioning of a municipal sewer

system. However, large quantities of these fluids, with their high protein content, might interfere with

the biological oxygen demand (BOD) of the system. Local municipal sewage treatment restrictions may

dictate that an alternative method of bulk fluid disposal be selected. State regulations may dictate what

quantity constitutes a small amount of blood or body fluids.

Although concerns have been raised about the discharge of blood and other body fluids to a septic tank

system, no evidence suggests that septic tanks have transmitted bloodborne infections. A properly

functioning septic system is adequate for inactivating bloodborne pathogens. System manufacturers’

instructions specify what materials may be discharged to the septic tank without jeopardizing its proper

operation.

6. Medical Waste and CJD

Concerns also have been raised about the need for special handling and treatment procedures for wastes

generated during the care of patients with CJD or other transmissible spongiform encephalopathies

(TSEs). Prions, the agents that cause TSEs, have significant resistance to inactivation by a variety of

physical, chemical, or gaseous methods.

1427

No epidemiologic evidence, however, links acquisition of

CJD with medical-waste disposal practices. Although handling neurologic tissue for pathologic

examination and autopsy materials with care, using barrier precautions, and following specific

117

procedures for the autopsy are prudent measures,

1197

employing extraordinary measures once the

materials are discarded is unnecessary. Regulated medical wastes generated during the care of the CJD

patient can be managed using the same strategies as wastes generated during the care of other patients.

After decontamination, these wastes may then be disposed in a sanitary landfill or discharged to the

sanitary sewer, as appropriate.

Part II. Recommendations for Environmental
Infection Control in Health-Care Facilities

A. Rationale for Recommendations

As in previous CDC guidelines, each recommendation is categorized on the basis of existing scientific

data, theoretic rationale, applicability, and possible economic benefit. The recommendations are

evidence-based wherever possible. However, certain recommendations are derived from empiric

infection-control or engineering principles, theoretic rationale, or from experience gained from events

that cannot be readily studied (e.g., floods).

The HICPAC system for categorizing recommendations has been modified to include a category for

engineering standards and actions required by state or federal regulations. Guidelines and standards

published by the American Institute of Architects (AIA), American Society of Heating, Refrigeration,

and Air-Conditioning Engineers (ASHRAE), and the Association for the Advancement in Medical

Instrumentation (AAMI) form the basis of certain recommendations. These standards reflect a

consensus of expert opinions and extensive consultation with agencies of the U.S. Department of Health

and Human Services. Compliance with these standards is usually voluntary. However, state and federal

governments often adopt these standards as regulations. For example, the standards from AIA regarding

construction and design of new or renovated health-care facilities, have been adopted by reference by

>40 states. Certain recommendations have two category ratings (e.g., Categories IA and IC or

Categories IB and IC), indicating the recommendation is evidence-based as well as a standard or

regulation.

B. Rating Categories

Recommendations are rated according to the following categories:

•

Category IA.

Strongly recommended for implementation and strongly supported by well-

designed experimental, clinical, or epidemiologic studies.

•

Category IB.

Strongly recommended for implementation and supported by certain

experimental, clinical, or epidemiologic studies and a strong theoretical rationale.

•

Category IC.

Required by state or federal regulation, or representing an established association

standard. (Note: Abbreviations for governing agencies and regulatory citations are listed, where

appropriate. Recommendations from regulations adopted at state levels are also noted.

Recommendations from AIA guidelines cite the appropriate sections of the standard).

•

Category II.

Suggested for implementation and supported by suggestive clinical or

epidemiologic studies, or a theoretical rationale.

•

Unresolved Issue.

No recommendation is offered. No consensus or insufficient evidence

exists regarding efficacy.

118

C. Recommendations—Air

Air-Handling Systems in Health-Care Facilities

A. Use AIA guidelines as minimum standards where state or local regulations are not in place

for design and construction of ventilation systems in new or renovated health-care facilities.

Ensure that existing structures continue to meet the specifications in effect at the time of

construction.

120

Category IC

(AIA: 1.1.A, 5.4)

B. Monitor ventilation systems in accordance with engineers’ and manufacturers’

recommendations to ensure preventive engineering, optimal performance for removal of

particulates, and elimination of excess moisture.

18, 35, 106, 120, 220, 222, 333, 336

Category IB, IC

(AIA: 7.2, 7.31.D, 8.31.D, 9.31.D, 10.31.D, 11.31.D, EPA guidance)

Ensure that heating, ventilation, air conditioning (HVAC) filters are properly installed

and maintained to prevent air leakages and dust overloads.

17, 18, 106, 222

Category IB

Monitor areas with special ventilation requirements (e.g., AII or PE) for ACH,

filtration, and pressure differentials.

21, 120, 249, 250, 273–275, 277, 333–344

Category IB, IC

(AIA: 7.2.C7, 7.2.D6)

Develop and implement a maintenance schedule for ACH, pressure

differentials, and filtration efficiencies using facility-specific data as part of the

multidisciplinary risk assessment. Take into account the age and reliability of

the system.

Document these parameters, especially the pressure differentials.

Engineer humidity controls into the HVAC system and monitor the controls to ensure

proper moisture removal.

120

Category IC

(AIA: 7.31.D9)

Locate duct humidifiers upstream from the final filters.

Incorporate a water-removal mechanism into the system.

Locate all duct takeoffs sufficiently down-stream from the humidifier so that

moisture is completely absorbed.

Incorporate steam humidifiers, if possible, to reduce potential for microbial

proliferation within the system, and avoid use of cool mist humidifiers.

Category II

Ensure that air intakes and exhaust outlets are located properly in construction of new

facilities and renovation of existing facilities.

3, 120

Category IC

(AIA: 7.31.D3, 8.31.D3,

9.31.D3, 10.31.D3, 11.31.D3)

Locate exhaust outlets >25 ft. from air-intake systems.

Locate outdoor air intakes >6 ft. above ground or >3 ft. above roof level.

Locate exhaust outlets from contaminated areas above roof level to minimize

recirculation of exhausted air.

Maintain air intakes and inspect filters periodically to ensure proper operation.

3, 120, 249,

250, 273–275, 277

Category IC

(AIA: 7.31.D8)

Bag dust-filled filters immediately upon removal to prevent dispersion of dust and

fungal spores during transport within the facility.

106, 221

Category IB

Seal or close the bag containing the discarded filter.

Discard spent filters as regular solid waste, regardless of the area from which

they were removed.

221

Remove bird roosts and nests near air intakes to prevent mites and fungal spores from

entering the ventilation system.

3, 98, 119

Category IB

Prevent dust accumulation by cleaning air-duct grilles in accordance with facility-

specific procedures and schedules when rooms are not occupied by patients.

21, 120, 249,

250, 273–275, 277

Category IC, II

(AIA: 7.31.D10)

119

10. Periodically measure output to monitor system function; clean ventilation ducts as

part of routine HVAC maintenance to ensure optimum performance.

120, 263, 264

Category II

(AIA: 7.31.D10)

C. Use portable, industrial-grade HEPA filter units capable of filtration rates in the range of

300–800 ft

/min. to augment removal of respirable particles as needed.

219

Category II

Select portable HEPA filters that can recirculate all or nearly all of the room air and

provide the equivalent of >12 ACH.

Category II

Portable HEPA filter units previously placed in construction zones can be used later

in patient-care areas, provided all internal and external surfaces are cleaned, and the

filter’s performance verified by appropriate particle testing.

Category II

Situate portable HEPA units with the advice of facility engineers to ensure that all

room air is filtered.

Category II

Ensure that fresh-air requirements for the area are met.

214, 219

Category II

D. Follow appropriate procedures for use of areas with through-the-wall ventilation units.

120

Category IC

(AIA: 8.31.D1, 8.31.D8, 9.31.D23, 10.31.D18, 11.31.D15)

Do not use such areas as PE rooms.

120

Category IC

(AIA: 7.2.D3)

Do not use a room with a through-the-wall ventilation unit as an AII room unless it

can be demonstrated that all required AII engineering controls required are met.

4, 120

Category IC

(AIA: 7.2.C3)

Conduct an infection-control risk assessment (ICRA) and provide an adequate number of

AII and PE rooms (if required) or other areas to meet the needs of the patient population.

4, 6,

9, 18, 19, 69, 94, 120, 142, 331–334, 336–338

Category IA, IC

(AIA: 7.2.C, 7.2.D)

When UVGI is used as a supplemental engineering control, install fixtures 1) on the wall

near the ceiling or suspended from the ceiling as an upper air unit; 2) in the air-return duct

of an AII room; or 3) in designated enclosed areas or booths for sputum induction.

Category II

G. Seal windows in buildings with centralized HVAC systems and especially with PE areas.

35,

111, 120

Category IB, IC

(AIA: 7.2.D3)

H. Keep emergency doors and exits from PE rooms closed except during an emergency; equip

emergency doors and exits with alarms.

Category II

Develop a contingency plan for backup capacity in the event of a general power failure.

713

Category IC

(Joint Commission on Accreditation of Healthcare Organizations [JCAHO]: Environment of Care [EC]

1.4)

Emphasize restoration of proper air quality and ventilation conditions in AII rooms,

PE rooms, operating rooms, emergency departments, and intensive care units.

120, 713

Category IC

(AIA: 1.5.A1; JCAHO: EC 1.4)

Deploy infection-control procedures to protect occupants until power and systems

functions are restored.

6, 120, 713

Category IC

(AIA: 5.1, 5.2; JCAHO: EC 1.4)

Do not shut down HVAC systems in patient-care areas except for maintenance, repair,

testing of emergency backup capacity, or new construction.

120, 206

Category IB, IC

(AIA:

5.1, 5.2.B, C)

Coordinate HVAC system maintenance with infection-control staff to allow for

relocation of immunocompromised patients if necessary.

120

Category IC

(AIA: 5.1,

5.2)

Provide backup emergency power and air-handling and pressurization systems to

maintain filtration, constant ACH, and pressure differentials in PE rooms, AII rooms,

operating rooms, and other critical-care areas.

9, 120, 278

Category IC

(AIA: 1.5, 5.1, 5.2)

For areas not served by installed emergency ventilation and backup systems, use

portable units and monitor ventilation parameters and patients in those areas.

219

Category II

Coordinate system startups with infection-control staff to protect patients in PE rooms

from bursts of fungal spores.

9, 35, 120, 278

Category IC

(AIA: 5.1, 5.2)

120

Allow sufficient time for ACH to clean the air once the system is operational

(Appendix B, Table B.1).

4, 120

Category IC

(AIA: 5.1, 5.2)

K. HVAC systems serving offices and administration areas may be shut down for energy

conservation purposes, but the shutdown must not alter or adversely affect pressure

differentials maintained in laboratories or critical-care areas with specific ventilation

requirements (i.e., PE rooms, AII rooms, operating rooms).

Category II

Whenever possible, avoid inactivating or shutting down the entire HVAC system at one

time, especially in acute-care facilities.

Category II

M. Whenever feasible, design and install fixed backup ventilation systems for new or renovated

construction for PE rooms, AII rooms, operating rooms, and other critical care areas

identified by ICRA.

120

Category IC

(AIA: 1.5.A1)

II.

Construction, Renovation, Remediation, Repair, and Demolition

A. Establish a multidisciplinary team that includes infection-control staff to coordinate

demolition, construction, and renovation projects and consider proactive preventive

measures at the inception; produce and maintain summary statements of the team’s

activities.

17, 19, 20, 97, 109, 120, 249, 250, 273–277

Category IB, IC

(AIA: 5.1)

B. Educate both the construction team and the health-care staff in immunocompromised

patient-care areas regarding the airborne infection risks associated with construction

projects, dispersal of fungal spores during such activities, and methods to control the

dissemination of fungal spores.

3, 249, 250, 273–277, 1428–1432

Category IB

C. Incorporate mandatory adherence agreements for infection control into construction

contracts, with penalties for noncompliance and mechanisms to ensure timely correction of

problems.

3, 120, 249, 273–277

Category IC

(AIA: 5.1)

D. Establish and maintain surveillance for airborne environmental disease (e.g., aspergillosis)

as appropriate during construction, renovation, repair, and demolition activities to ensure

the health and safety of immunocompromised patients.

3, 64, 65, 79

Category IB

Using active surveillance, monitor for airborne fungal infections in

immunocompromised patients.

3, 9, 64, 65

Category IB

Periodically review the facility’s microbiologic, histopathologic, and postmortem data

to identify additional cases.

3, 9, 64, 65

Category IB

If cases of aspergillosis or other health-care–associated airborne fungal infections

occur, aggressively pursue the diagnosis with tissue biopsies and cultures as feasible.

64, 65, 79, 249, 273–277

Category IB

Implement infection-control measures relevant to construction, renovation, maintenance,

demolition, and repair.

96, 97, 120, 276, 277

Category IB, IC

(AIA: 5.1, 5.2)

Before the project gets underway, perform an ICRA to define the scope of the project

and the need for barrier measures.

96, 97, 120, 249, 273–277

Category IB, IC

(AIA: 5.1)

Determine if immunocompromised patients may be at risk for exposure to

fungal spores from dust generated during the project.

20, 109, 273–275, 277

Develop a contingency plan to prevent such exposures.

20, 109, 273–275, 277

Implement infection-control measures for external demolition and construction

activities.

50, 249, 273–277, 283

Category IB

Determine if the facility can operate temporarily on recirculated air; if feasible,

seal off adjacent air intakes.

If this is not possible or practical, check the low-efficiency (roughing) filter

banks frequently and replace as needed to avoid buildup of particulates.

Seal windows and reduce wherever possible other sources of outside air

intrusion (e.g., open doors in stairwells and corridors), especially in PE areas.

Avoid damaging the underground water distribution system (i.e., buried pipes) to

prevent soil and dust contamination of the water.

120, 305

Category IB, IC

(AIA: 5.1)

121

Implement infection-control measures for internal construction activities.

20, 49, 97, 120,

249, 273–277

Category IB, IC

(AIA: 5.1, 5.2)

Construct barriers to prevent dust from construction areas from entering

patient-care areas; ensure that barriers are impermeable to fungal spores and in

compliance with local fire codes.

20, 49, 97, 120, 284, 312, 713, 1431

Block and seal off return air vents if rigid barriers are used for containment.

120,

276, 277

Implement dust control measures on surfaces and by diverting pedestrian traffic

away from work zones.

20, 49, 97, 120

Relocate patients whose rooms are adjacent to work zones, depending upon

their immune status, the scope of the project, the potential for generation of

dust or water aerosols, and the methods used to control these aerosols.

49, 120, 281

Perform those engineering and work-site related infection-control measures as needed

for internal construction, repairs, and renovations:

20, 49, 97, 109, 120, 312

Category IB, IC

(AIA: 5.1, 5.2)

Ensure proper operation of the air-handling system in the affected area after

erection of barriers and before the room or area is set to negative pressure.

49, 69,

276, 278

Category IB

Create and maintain negative air pressure in work zones adjacent to patient-care

areas and ensure that required engineering controls are maintained.

20, 49, 97, 109, 120,

312

Monitor negative air flow inside rigid barriers.

120, 281

Monitor barriers and ensure the integrity of the construction barriers; repair

gaps or breaks in barrier joints.

120, 284, 307, 312

Seal windows in work zones if practical; use window chutes for disposal of

large pieces of debris as needed, but ensure that the negative pressure

differential for the area is maintained.

20, 120, 273

Direct pedestrian traffic from construction zones away from patient-care areas

to minimize the dispersion of dust.

20, 49, 97, 109, 111, 120, 273–277

Provide construction crews with 1) designated entrances, corridors, and

elevators whenever practical; 2) essential services [e.g., toilet facilities], and

convenience services [e.g., vending machines]; 3) protective clothing [e.g.,

coveralls, footgear, and headgear] for travel to patient-care areas; and 4) a space

or anteroom for changing clothing and storing equipment.

120, 249, 273–277

Clean work zones and their entrances daily by 1) wet-wiping tools and tool

carts before their removal from the work zone; 2) placing mats with tacky

surfaces inside the entrance; and 3) covering debris and securing this covering

before removing debris from the work zone.

120, 249, 273–277

In patient-care areas, for major repairs that include removal of ceiling tiles and

disruption of the space above the false ceiling, use plastic sheets or

prefabricated plastic units to contain dust; use a negative pressure system

within this enclosure to remove dust; and either pass air through an industrial

grade, portable HEPA filter capable of filtration rates ranging from 300–800

/min., or exhaust air directly to the outside.

49, 276, 277, 281, 309

Upon completion of the project, clean the work zone according to facility

procedures, and install barrier curtains to contain dust and debris before

removal of rigid barriers.

20, 97, 120, 249, 273–277

Flush the water system to clear sediment from pipes to minimize waterborne

microorganism proliferation.

120, 305

Restore appropriate ACH, humidity, and pressure differential; clean or replace

air filters; dispose of spent filters.

35, 106, 221, 278

122

Use airborne-particle sampling as a tool to evaluate barrier integrity.

35, 100

Category II

G. Commission the HVAC system for newly constructed health-care facilities and renovated

spaces before occupancy and use, with emphasis on ensuring proper ventilation for

operating rooms, AII rooms, and PE areas.

100, 120, 288, 304

Category IC

(AIA: 5.1; ASHRAE: 1-

1996)

No recommendation is offered

on routine microbiologic air sampling before, during, or

after construction or before or during occupancy of areas housing immunocompromised

patients.

17, 20, 49, 97, 109, 272, 1433

Unresolved issue

If a case of health-care–acquired aspergillosis or other opportunistic environmental airborne

fungal disease occurs during or immediately after construction, implement appropriate

follow-up measures.

20, 55, 62, 77, 94, 95

Category IB

Review pressure differential monitoring documentation to verify that pressure

differentials in the construction zone and in PE rooms were appropriate for their

settings.

94, 95, 120

Category IB, IC

(AIA: 5.1)

Implement corrective engineering measures to restore proper pressure differentials as

needed.

94, 95, 120

Category IB, IC

(AIA: 5.1)

Conduct a prospective search for additional cases and intensify retrospective

epidemiologic review of the hospital’s medical and laboratory records.

3, 20, 62, 63, 104

Category IB

If there is no evidence of ongoing transmission, continue routine maintenance in the

area to prevent health-care–acquired fungal disease.

3, 55

Category IB

If there is epidemiologic evidence of ongoing transmission of fungal disease, conduct an

environmental assessment to determine and eliminate the source.

3, 96, 97, 109, 111, 115, 249, 273–277

Category IB

Collect environmental samples from potential sources of airborne fungal spores,

preferably using a high-volume air sampler rather than settle plates.

3, 18, 44, 48, 49, 97, 106,

111, 112, 115, 249, 254, 273–277, 292, 312

Category IB

If either an environmental source of airborne fungi or an engineering problem with

filtration or pressure differentials is identified, promptly perform corrective measures

to eliminate the source and route of entry.

96, 97

Category IB

Use an EPA-registered anti-fungal biocide (e.g., copper-8-quinolinolate) for

decontaminating structural materials.

50, 277, 312, 329

Category IB

If an environmental source of airborne fungi is not identified, review infection control

measures, including engineering controls, to identify potential areas for correction or

improvement.

73, 117

Category IB

If possible, perform molecular subtyping of

Aspergillus

spp. isolated from patients

and the environment to establish strain identities.

252, 293–296

Category II

K. If air-supply systems to high-risk areas (e.g., PE rooms) are not optimal, use portable,

industrial-grade HEPA filters on a temporary basis until rooms with optimal air-handling

systems become available.

3, 120, 273–277

Category II

III. Infection-Control and Ventilation Requirements for PE Rooms

A. Minimize exposures of severely immunocompromised patients (e.g., solid organ transplant

patients or allogeneic neutropenic patients) to activities that might cause aerosolization of

fungal spores (e.g., vacuuming or disruption of ceiling tiles).

9, 20, 109, 272

Category IB

B. Minimize the length of time that immunocompromised patients in PE are outside their

rooms for diagnostic procedures and other activities.

9, 283

Category IB

C. Provide respiratory protection for severely immunocompromised patients when they must

leave PE for diagnostic studies and other activities; consult the most recent revision of

CDC’s

Guidelines for Prevention of Health-Care–Associated Pneumonia

for information

regarding the appropriate type of respiratory protection.

3, 9

Category II

123

D. Incorporate ventilation engineering specifications and dust-controlling processes into the

planning and construction of new PE units.

Category IB, IC

Install central or point-of-use HEPA filters for supply (incoming) air.

3, 18, 20, 44, 99–104,

120, 254, 316–318, 1432, 1434

Category IB, IC

(AIA: 5.1, 5.2, 7.2.D)

Ensure that rooms are well sealed by 1) properly constructing windows, doors, and

intake and exhaust ports; 2) maintaining ceilings that are smooth and free of fissures,

open joints, and crevices; 3) sealing walls above and below the ceiling, and 4)

monitoring for leakage and making necessary repairs.

3, 111, 120, 317, 318

Category IB,

(AIA: 7.2.D3)

Ventilate the room to maintain >12 ACH.

3, 9, 120, 241, 317, 318

Category IC

(AIA: 7.2.D)

Locate air supply and exhaust grilles so that clean, filtered air enters from one side of

the room, flows across the patient’s bed, and exits from the opposite side of the

room.

3, 120, 317, 318

Category IC

(AIA: 7.31.D1)

Maintain positive room air pressure (>2.5 Pa [0.01-inch water gauge]) in relation to

the corridor.

3, 35, 120, 317, 318

Category IB, IC

(AIA: Table 7.2)

Maintain airflow patterns and monitor these on a daily basis by using permanently

installed visual means of detecting airflow in new or renovated construction, or using

other visual methods (e.g., flutter strips, or smoke tubes) in existing PE units.

Document the monitoring results.

120, 273

Category IC

(AIA: 7.2.D6)

Install self-closing devices on all room exit doors in protective environments.

120

Category IC

(AIA: 7.2.D4)

Do not use laminar air flow systems in newly constructed PE rooms.

316, 318

Category II

Take measures to protect immunocompromised patients who would benefit from a PE room

and who also have an airborne infectious disease (e.g., acute VZV infection or

tuberculosis).

Ensure that the patient’s room is designed to maintain positive pressure.

Use an anteroom to ensure appropriate air balance relationships and provide

independent exhaust of contaminated air to the outside, or place a HEPA filter in the

exhaust duct if the return air must be recirculated.

120, 317

Category IC

(AIA: 7.2.D1,

A7.2.D)

If an anteroom is not available, place the patient in AII and use portable, industrial-

grade HEPA filters to enhance filtration of spores in the room.

219

Category II

G. Maintain backup ventilation equipment (e.g., portable units for fans or filters) for

emergency provision of ventilation requirements for PE areas and take immediate steps to

restore the fixed ventilation system function.

9, 120, 278

Category IC

(AIA: 5.1)

IV. Infection-Control and Ventilation Requirements for AII Rooms

A. Incorporate certain specifications into the planning, and construction or renovation of AII

units.

4, 107, 120, 317, 318

Category IB, IC

Maintain continuous negative air pressure (2.5 Pa [0.01-inch water gauge]) in relation

to the air pressure in the corridor; monitor air pressure periodically, preferably daily,

with audible manometers or smoke tubes at the door (for existing AII rooms) or with

a permanently installed visual monitoring mechanism. Document the results of

monitoring.

120, 317, 318

Category IB, IC

(AIA: 7.2.C7, Table 7.2)

Ensure that rooms are well-sealed by properly constructing windows, doors, and air-

intake and exhaust ports; when monitoring indicates air leakage, locate the leak and

make necessary repairs.

120, 317, 318

Category IB, IC

(AIA: 7.2.C3)

Install self-closing devices on all AII room exit doors.

120

Category IC

(AIA: 7.2.C4)

Provide ventilation to ensure >12 ACH for renovated rooms and new rooms, and >6

ACH for existing AII rooms.

4, 107, 120

Category IC

(AIA: Table 7.2)

124

Direct exhaust air to the outside, away from air-intake and populated areas. If this is

not practical, air from the room can be recirculated after passing through a HEPA

filter.

4, 120

Category IC

(AIA: Table 7.2)

B. Where supplemental engineering controls for air cleaning are indicated from a risk

assessment of the AII area, install UVGI units in the exhaust air ducts of the HVAC system

to supplement HEPA filtration or install UVGI fixtures on or near the ceiling to irradiate

upper room air.

Category II

C. Implement environmental infection-control measures for persons with known or suspected

airborne infectious diseases.

Use AII rooms for patients with or suspected of having an airborne infection who also

require cough-inducing procedures, or use an enclosed booth that is engineered to

provide 1) >12 ACH; 2) air supply and exhaust rate sufficient to maintain a 2.5 Pa

[0.01-inch water gauge] negative pressure difference with respect to all surrounding

spaces with an exhaust rate of >50 ft

/min.; and 3) air exhausted directly outside away

from air intakes and traffic or exhausted after HEPA filtration prior to recirculation.

120, 348–350

Category IB, IC

(AIA: 7.15.E, 7.31.D23, 9.10, Table 7.2)

Although airborne spread of viral hemorrhagic fever (VHF) has not been documented

in a health-care setting, prudence dictates placing a VHF patient in an AII room,

preferably with an anteroom to reduce the risk of occupational exposure to

aerosolized infectious material in blood, vomitus, liquid stool, and respiratory

secretions present in large amounts during the end stage of a patient’s illness.

202–204

Category II

If an anteroom is not available, use portable, industrial-grade HEPA filters in

the patient’s room to provide additional ACH equivalents for removing

airborne particulates.

Ensure that health-care workers wear face shields or goggles with appropriate

respirators when entering the rooms of VHF patients with prominent cough,

vomiting, diarrhea, or hemorrhage.

203

Place smallpox patients in negative pressure rooms at the onset of their illness,

preferably using a room with an anteroom if available.

Category II

No recommendation is offered

regarding negative pressure or isolation rooms for patients

with

Pneumocystis carinii

pneumonia.

126, 131, 132

Unresolved issue

Maintain back-up ventilation equipment (e.g., portable units for fans or filters) for

emergency provision of ventilation requirements for AII rooms and take immediate steps to

restore the fixed ventilation system function.

4, 120, 278

Category IC

(AIA: 5.1)

Infection-Control and Ventilation Requirements for Operating Rooms

A. Implement environmental infection-control and ventilation measures for operating rooms.

1. Maintain

positive-pressure ventilation with respect to corridors and adjacent areas.

120, 356

Category IB, IC

(AIA: Table 7.2)

2. Maintain

>15 ACH, of which >3 ACH should be fresh air.

120, 357, 358

Category IC

(AIA: Table 7.2)

Filter all recirculated and fresh air through the appropriate filters, providing 90%

efficiency (dust-spot testing) at a minimum.

120, 362

Category IC

(AIA: Table 7.3)

In rooms not engineered for horizontal laminar airflow, introduce air at the ceiling

and exhaust air near the floor.

120, 357, 359

Category IC

(AIA: 7.31.D4)

Do not use UV lights to prevent surgical-site infections.

356, 364–370

Category IB

Keep operating room doors closed except for the passage of equipment, personnel,

and patients, and limit entry to essential personnel.

351, 352

Category IB

B. Follow precautionary procedures for TB patients who also require emergency surgery.

4, 347,

371

Category IB, IC

125

Use an N95 respirator approved by the National Institute for Occupational Safety and

Health (NIOSH) without exhalation valves in the operating room.

347, 372

Category

(Occupational Safety and Health Administration [OSHA]; 29 Code of Federal Regulations [CFR]

1910.134,139)

Intubate the patient in either the AII room or the operating room; if intubating the

patient in the operating room, do not allow the doors to open until 99% of the

airborne contaminants are removed (Appendix B, Table B.1).

4, 358

Category IB

When anesthetizing a patient with confirmed or suspected TB, place a bacterial filter

between the anesthesia circuit and patient’s airway to prevent contamination of

anesthesia equipment or discharge of tubercle bacilli into the ambient air.

371, 373

Category IB

Extubate and allow the patient to recover in an AII room.

4, 358

Category IB

If the patient has to be extubated in the operating room, allow adequate time for ACH

to clean 99% of airborne particles from the air (Appendix B, Table B.1) because

extubation is a cough-producing procedure.

4, 358

Category IB

C. Use portable, industrial-grade HEPA filters temporarily for supplemental air cleaning

during intubation and extubation for infectious TB patients who require surgery.

4, 219, 358

Category II

Position the units appropriately so that all room air passes through the filter; obtain

engineering consultation to determine the appropriate placement of the unit.

Category II

Switch the portable unit off during the surgical procedure.

Category II

Provide fresh air as per ventilation standards for operating rooms; portable units do

not meet the requirements for the number of fresh ACH.

120, 215, 219

Category II

D. If possible, schedule infectious TB patients as the last surgical cases of the day to maximize

the time available for removal of airborne contamination.

Category II

No recommendation is offered

for performing orthopedic implant operations in rooms

supplied with laminar airflow.

362, 364

Unresolved issue

F. Maintain

backup

ventilation

equipment (e.g., portable units for fans or filters) for

emergency provision of ventilation requirements for operating rooms, and take immediate

steps to restore the fixed ventilation system function.

68, 120, 278,372

Category IB, IC

(AIA:

5.1)

VI. Other Potential Infectious Aerosol Hazards in Health-Care Facilities

A. In settings where surgical lasers are used, wear appropriate personal protective equipment,

including N95 or N100 respirators, to minimize exposure to laser plumes.

347, 378, 389

Category IC

(OSHA; 29 CFR 1910.134,139)

B. Use central wall suction units with in-line filters to evacuate minimal laser plumes.

378, 382, 386,

389

Category II

C. Use a mechanical smoke evacuation system with a high-efficiency filter to manage the

generation of large amounts of laser plume, when ablating tissue infected with human

papilloma virus (HPV) or performing procedures on a patient with extrapulmonary TB.

4, 382,

389– 392

Category II

D. Recommendations—Water

Controlling the Spread of Waterborne Microoganisms

A. Practice hand hygiene to prevent the hand transfer of waterborne pathogens, and use barrier

precautions (e.g., gloves) as defined by other guidelines.

6, 464, 577, 586, 592, 1364

Category IA

126

B. Eliminate contaminated water or fluid environmental reservoirs (e.g., in equipment or

solutions) wherever possible.

464, 465

Category IB

C. Clean and disinfect sinks and wash basins on a regular basis by using an EPA-registered

product as set by facility policies.

Category II

D. Evaluate for possible environmental sources (e.g., potable water) of specimen

contamination when waterborne microorganisms (e.g., NTM) of unlikely clinical

importance are isolated from clinical cultures (e.g., specimens collected aseptically from

sterile sites or, if post-procedural, colonization occurs after use of tap water in patient

care).

607, 610–612

Category IB

Avoid placing decorative fountains and fish tanks in patient-care areas; ensure disinfection

and fountain maintenance if decorative fountains are used in the public areas of the health-

care facility.

664

Category IB

II.

Routine Prevention of Waterborne Microbial Contamination Within the Distribution
System

A. Maintain hot water temperature at the return at the highest temperature allowable by state

regulations or codes, preferably >124°F (>51°C), and maintain cold water temperature at

<68°F (<20°C).

3, 661

Category IC

(States; ASHRAE: 12:2000)

B. If the hot water temperature can be maintained at >124°F (>51°C), explore engineering

options (e.g., install preset thermostatic valves in point-of-use fixtures) to help minimize the

risk of scalding.

661

Category II

C. When state regulations or codes do not allow hot water temperatures above the range of

105°F–120°F (40.6°C–49°C) for hospitals or 95°F–110°F (35°C–43.3°C) for nursing care

facilities or when buildings cannot be retrofitted for thermostatic mixing valves, follow

either of these alternative preventive measures to minimize the growth of

Legionella

spp. in

water systems.

Category II

Periodically increase the hot water temperature to >150°F (>66°C) at the point of

use.

661

Category II

Alternatively, chlorinate the water and then flush it through the system.

661, 710, 711

Category II

D. Maintain constant recirculation in hot-water distribution systems serving patient-care

areas.

120

Category IC

(AIA: 7.31.E.3)

III. Remediation Strategies for Distribution System Repair or Emergencies

A. Whenever possible, disconnect the ice machine before planned water disruptions.

Category II

B. Prepare a contingency plan to estimate water demands for the entire facility in advance of

significant water disruptions (i.e., those expected to result in extensive and heavy microbial

or chemical contamination of the potable water), sewage intrusion, or flooding.

713, 719

Category IC

(JCAHO: EC 1.4)

C. When a significant water disruption or an emergency occurs, adhere to any advisory to boil

water issued by the municipal water utility.

642

Category IB, IC

(Municipal order)

Alert patients, families, staff, and visitors not to consume water from drinking

fountains, ice, or drinks made from municipal tap water, while the advisory is in

effect, unless the water has been disinfected (e.g., by bringing to a rolling boil for >1

minute).

642

Category IB, IC

(Municipal order)

After the advisory is lifted, run faucets and drinking fountains at full flow for >5

minutes, or use high-temperature water flushing or chlorination.

642, 661

Category IC,

(Municipal order; ASHRAE 12:2000)

D. Maintain a high level of surveillance for waterborne disease among patients after a boil

water advisory is lifted.

Category II

127

Corrective decontamination of the hot water system might be necessary after a disruption in

service or a cross-connection with sewer lines has occurred.

Decontaminate the system when the fewest occupants are present in the building (e.g.,

nights or weekends).

3, 661

Category IC

(ASHRAE: 12:2000)

If using high-temperature decontamination, raise the hot-water temperature to 160°F–

170°F (71°C–77°C) and maintain that level while progressively flushing each outlet

around the system for >5 minutes.

3, 661

Category IC

(ASHRAE: 12:2000)

If using chlorination, add enough chlorine, preferably overnight, to achieve a free

chlorine residual of >2 mg/L (>2 ppm) throughout the system.

661

Category IC

(ASHRAE: 12:2000)

Flush each outlet until chlorine odor is detected.

Maintain the elevated chlorine concentration in the system for >2 hrs (but <24

hrs).

Use a very thorough flushing of the water system instead of chlorination if a highly

chlorine-resistant microorganism (e.g.,

Cryptosporidium

spp.) is suspected as the

water contaminant.

Category II

Flush and restart equipment and fixtures according to manufacturers’ instructions.

Category II

G. Change the pretreatment filter and disinfect the dialysis water system with an EPA-

registered product to prevent colonization of the reverse osmosis membrane and

downstream microbial contamination.

721

Category II

H. Run water softeners through a regeneration cycle to restore their capacity and function.

Category II

If the facility has a water-holding reservoir or water-storage tank, consult the facility

engineer or local health department to determine whether this equipment needs to be

drained, disinfected with an EPA-registered product, and refilled.

Category II

Implement facility management procedures to manage a sewage system failure or flooding

(e.g., arranging with other health-care facilities for temporary transfer of patients or

provision of services), and establish communications with the local municipal water utility

and the local health department to ensure that advisories are received in a timely manner

upon release.

713, 719

Category IC

(JCAHO: EC 1.4; Municipal order)

K. Implement infection-control measures during sewage intrusion, flooding, or other water-

related emergencies.

Relocate patients and clean or sterilize supplies from affected areas.

Category II

If hands are not visibly soiled or contaminated with proteinaceous material, include

an alcohol-based hand rub in the hand hygiene process 1) before performing invasive

procedures; 2) before and after each patient contact; and 3) whenever hand hygiene is

indicated.

1364

Category II

If hands are visibly soiled or contaminated with proteinaceous material, use soap and

bottled water for handwashing.

1364

Category II

If the potable water system is not affected by flooding or sewage contamination,

process surgical instruments for sterilization according to standard procedures.

Category II

Contact the manufacturer of the automated endoscope reprocessor (AER) for specific

instructions on the use of this equipment during a water advisory.

Category II

Remediate the facility after sewage intrusion, flooding, or other water-related emergencies.

Close off affected areas during cleanup procedures.

Category II

Ensure that the sewage system is fully functional before beginning remediation so

contaminated solids and standing water can be removed.

Category II

128

If hard-surface equipment, floors, and walls remain in good repair, ensure that these

are dry within 72 hours; clean with detergent according to standard cleaning

procedures.

Category II

Clean wood furniture and materials (if still in good repair); allow them to dry

thoroughly before restoring varnish or other surface coatings.

Category II

Contain dust and debris during remediation and repair as outlined in air

recommendations (Air: II G 4, 5).

Category II

M. Regardless of the original source of water damage (e.g., flooding versus water leaks from

point-of-use fixtures or roofs), remove wet, absorbent structural items (e.g., carpeting,

wallboard, and wallpaper) and cloth furnishings if they cannot be easily and thoroughly

cleaned and dried within 72 hours (e.g., moisture content <20% as determined by moisture

meter readings); replace with new materials as soon as the underlying structure is declared

by the facility engineer to be thoroughly dry.

18, 266, 278, 1026

Category IB

IV. Additional Engineering Measures as Indicated by Epidemiologic Investigation for

Controlling Waterborne, Health-Care–Associated Legionnaires Disease

A. When using a pulse or one-time decontamination method, superheat the water by flushing

each outlet for >5 minutes with water at 160°F–170°F (71°C–77°C) or hyperchlorinate the

system by flushing all outlets for >5 minutes with water containing >2 mg/L (>2 ppm) free

residual chlorine using a chlorine-based product registered by the EPA for water treatment

(e.g., sodium hypochlorite [chlorine bleach]).

661, 711, 714, 724, 764, 766

Category IB

(ASHRAE:

12:2000)

B. After a pulse treatment, maintain both the heated water temperature at the return and the

cold water temperature as per the recommendation (Water: IIA) wherever practical and

permitted by state codes, or chlorinate heated water to achieve 1–2 mg/L (1–2 ppm) free

residual chlorine at the tap using a chlorine-based product registered by the EPA for water

treatment (e.g., sodium hypochlorite [bleach]).

26, 437, 661, 709, 726, 727

Category IC

(States;

ASHRAE: 12:2000)

C. Explore engineering or educational options (e.g., install preset thermostatic mixing valves

in point-of-use fixtures or post warning signs at each outlet) to minimize the risk of scalding

for patients, visitors, and staff.

Category II

No recommendation is offered

for treating water in the facility’s distribution system with

chlorine dioxide, heavy-metal ions (e.g., copper or silver), monochloramine, ozone, or UV

light.

728–746

Unresolved issue

General Infection-Control Strategies for Preventing Legionnaires Disease

A. Conduct an infection-control risk assessment of the facility to determine if patients at risk or

severely immunocompromised patients are present.

3, 431, 432

Category IB

B. Implement general strategies for detecting and preventing Legionnaires disease in facilities

that do not provide care for severely immunocompromised patients (i.e., facilities that do

not have HSCT or solid organ transplant programs).

3, 431, 432

Category IB

Establish a surveillance process to detect health-care–associated Legionnaires

disease.

3, 431, 432

Category IB

Inform health-care personnel (e.g., infection control, physicians, patient-care staff,

and engineering) regarding the potential for Legionnaires disease to occur and

measures to prevent and control health-care–associated legionellosis.

437, 759

Category IB

Establish mechanisms to provide clinicians with laboratory tests (e.g., culture, urine

antigen, direct fluorescence assay [DFA], and serology) for the diagnosis of

Legionnaires disease.

3, 431

Category IB

129

C. Maintain a high index of suspicion for health-care–associated Legionnaires disease, and

perform laboratory diagnostic tests for legionellosis on suspected cases, especially in

patients at risk who do not require a PE for care (e.g., patients receiving systemic steroids;

patients aged >65 years; or patients with chronic underlying disease [e.g., diabetes mellitus,

congestive heart failure, or chronic obstructive lung disease]).

3, 395, 417, 423–425, 432, 435, 437, 453

Category IA

D. Periodically review the availability and clinicians’ use of laboratory diagnostic tests for

Legionnaires disease in the facility; if clinicians’ use of the tests on patients with diagnosed

or suspected pneumonia is limited, implement measures (e.g., an educational campaign) to

enhance clinicians’ use of the test(s).

453

Category IB

If one case of laboratory-confirmed, health-care–associated Legionnaires disease is

identified, or if two or more cases of laboratory-suspected, health-care–associated

Legionnaires disease occur during a 6-month period, certain activities should be initiated.

405,

408, 431, 453, 739, 759

Category IB

Report the cases to the state and local health departments where required.

Category

(States)

If the facility does not treat severely immunocompromised patients, conduct an

epidemiologic investigation, including retrospective review of microbiologic,

serologic, and postmortem data to look for previously unidentified cases of health-

care–associated Legionnaires disease, and begin intensive prospective surveillance for

additional cases.

3, 405, 408, 431, 453, 739, 759

Category IB

If no evidence of continued health-care–associated transmission exists, continue

intensive prospective surveillance for >2 months after the initiation of surveillance.

405, 408, 431, 453, 739, 759

Category IB

If there is evidence of continued health-care–associated transmission (i.e., an outbreak),

conduct an environmental assessment to determine the source of

Legionella

spp.

403–410, 455

Category IB

Collect water samples from potential aerosolized water sources (Appendix C).

1209

Category IB

Save and subtype isolates of

Legionella

spp. obtained from patients and the

environment.

403–410, 453, 763, 764

Category IB

If a source is identified, promptly institute water system decontamination measures

per recommendations (see Water IV).

766, 767

Category IB

4. If

Legionella

spp. are detected in >1cultures (e.g., conducted at 2-week intervals

during 3 months), reassess the control measures, modify them accordingly, and repeat

the decontamination procedures; consider intensive use of techniques used for initial

decontamination, or a combination of superheating and hyperchlorination.

3, 767, 768

Category IB

G. If an environmental source is not identified during a Legionnaires disease outbreak,

continue surveillance for new cases for >2 months. Either defer decontamination pending

identification of the source of

Legionella

spp., or proceed with decontamination of the

hospital's water distribution system, with special attention to areas involved in the outbreak.

Category II

No recommendation is offered

regarding routine culturing of water systems in health-care

facilities that do not have patient-care areas (i.e., PE or transplant units) for persons at high

risk for

Legionella

spp. infection.

26, 453, 707, 709, 714, 747, 753

Unresolved issue

No recommendation is offered

regarding the removal of faucet aerators in areas for

immunocompetent patients.

Unresolved issue

Keep adequate records of all infection-control measures and environmental test results for

potable water systems.

Category II

130

VI. Preventing Legionnaires Disease in Protective Environments and Transplant Units

A. When implementing strategies for preventing Legionnaires disease among severely

immunosuppressed patients housed in facilities with HSCT or solid-organ transplant

programs, incorporate these specific surveillance and epidemiologic measures in addition to

the steps previously outlined (Water: V and Appendix C).

Maintain a high index of suspicion for legionellosis in transplant patients even when

environmental surveillance cultures do not yield legionellae.

430, 431

Category IB

If a case occurs in a severely immunocompromised patient, or if severely

immunocompromised patients are present in high-risk areas of the hospital (e.g., PE

or transplant units) and cases are identified elsewhere in the facility, conduct a

combined epidemiologic and environmental investigation to determine the source of

Legionella

spp.

431, 767

Category IB

B. Implement culture strategies and potable water and fixture treatment measures in addition to

those previously outlined (Water: V).

Category II

Depending on state regulations on potable water temperature in public buildings,

725

hospitals housing patients at risk for health-care–associated legionellosis should either

maintain heated water with a minimum return temperature of >124°F [>51°C] and

cold water at <68°F [<20°C]), or chlorinate heated water to achieve 1–2 mg/L (1–2

ppm) of free residual chlorine at the tap.

26, 441, 661, 709–711, 726, 727

Category II

Periodic culturing for legionellae in potable water samples from HSCT or solid-organ

transplant units can be performed as part of a comprehensive strategy to prevent

Legionnaires disease in these units.

9, 431, 710, 769

Category II

No recommendation is offered

regarding the optimal methodology (i.e., frequency

or number of sites) for environmental surveillance cultures in HSCT or solid organ

transplant units.

Unresolved issue

In areas with patients at risk, when

Legionella

spp. are not detectable in unit water,

remove, clean, and disinfect shower heads and tap aerators monthly by using a

chlorine-based, EPA-registered product. If an EPA-registered chlorine disinfectant is

not available, use a chlorine bleach solution (500–615 ppm [1:100 v/v dilution]).

661, 745

Category II

C. If

Legionella

spp. are determined to be present in the water of a transplant unit, implement

certain measures until

Legionella

spp. are no longer detected by culture.

Decontaminate the water supply as outlined previously (Water: IV).

3, 9, 661, 766, 767

Category IB

Do not use water from the faucets in patient-care rooms to avoid creating infectious

aerosols.

9, 412

Category IB

Restrict severely immunocompromised patients from taking showers.

9, 412

Category

Use water that is not contaminated with

Legionella

spp. for HSCT patients’ sponge

baths.

9, 412

Category IB

Provide patients with sterile water for tooth brushing, drinking, and for flushing

nasogastric tubing during legionellosis outbreaks.

9, 412

Category IB

D. Do not use large-volume room air humidifiers that create aerosols (e.g., by Venturi

principle, ultrasound, or spinning disk) unless they are subjected to high-level disinfection

and filled only with sterile water.

3, 9, 402, 455

Category IB

VII. Cooling Towers and Evaporative Condensers

A. When planning construction of new health-care facilities, locate cooling towers so that the

drift is directed away from the air-intake system, and design the towers to minimize the

volume of aerosol drift.

404, 661, 786

Category IC

(ASHRAE: 12:2000)

131

B. Implement infection-control procedures for operational cooling towers.

404, 661, 784

Category IC

(ASHRAE: 12:2000)

Install drift eliminators.

404, 661, 784

Category IC

(ASHRAE: 12:2000)

Use an effective EPA-registered biocide on a regular basis.

661

Category IC

(ASHRAE: 12:2000)

Maintain towers according to manufacturers’ recommendations, and keep detailed

maintenance and infection control records, including environmental test results from

legionellosis outbreak investigations.

661

Category IC

(ASHRAE: 12:2000)

C. If cooling towers or evaporative condensers are implicated in health-care–associated

legionellosis, decontaminate the cooling-tower system.

404, 405, 786, 787

Category IB

VIII. Dialysis Water Quality and Dialysate

A. Adhere to current AAMI standards for quality assurance performance of devices and

equipment used to treat, store, and distribute water in hemodialysis centers (both acute and

maintenance [chronic] settings) and for the preparation of concentrates and dialysate.

31, 32,

666–668, 789, 791, 800, 807, 809, 1454, 1455

Category IA, IC

(AAMI: ANSI/AAMI RD5:1992, ANSI/AAMI RD

47:1993)

No recommendation is offered

regarding whether more stringent requirements for water

quality should be imposed in hemofiltration and hemodiafiltration.

Unresolved issue

C. Conduct microbiological testing specific to water in dialysis settings.

789, 791, 792, 834, 835

Category IA, IC

(AAMI: ANSI/AAMI RD 5: 1992, ANSI/AAMI RD 47: 1993, ANSI/AAMI RD 62:2001)

Perform bacteriologic assays of water and dialysis fluids at least once a month and

during outbreaks using standard quantitative methods.

792, 834, 835

Category IA, IC

(AAMI: ANSI/AAMI RD 62:2001)

Assay for heterotrophic, mesophilic bacteria (e.g.,

Pseudomonas

spp).

Do not use nutrient-rich media (e.g., blood agar or chocolate agar).

In conjunction with microbiological testing, perform endotoxin testing on product

water used to reprocess dialyzers for multiple use.

789, 791, 806, 811, 816, 829

Category IA,

(AAMI: ANSI/AAMI RD 5:1992, ANSI/AAMI RD 47:1993)

Ensure that water does not exceed the limits for microbial counts and endotoxin

concentrations outlined in Table 18.

789, 791, 800

Category IA, IC

(AAMI: ANSI/AAMI RD

5:1992, ANSI/AAMI RD 47:1993)

D. Disinfect water distribution systems in dialysis settings on a regular schedule. Monthly

disinfection is recommended.

666–668, 792, 800

Category IA, IC

(AAMI: ANSI/AAMI RD62:2001)

Whenever practical, design and engineer water systems in dialysis settings to avoid

incorporating joints, dead-end pipes, and unused branches and taps that can harbor

bacteria.

666–668, 792, 800

Category IA, IC

(AAMI: ANSI/AAMI RD62:2001)

When storage tanks are used in dialysis systems, they should be routinely drained,

disinfected with an EPA-registered product, and fitted with an ultrafilter or pyrogenic filter

(membrane filter with a pore size sufficient to remove small particles and molecules >1

kilodalton) installed in the water line distal to the storage tank.

792

Category IC

(AAMI:

ANSI/AAMI RD62:2001)

IX. Ice Machines and Ice

A. Do not handle ice directly by hand, and wash hands before obtaining ice.

Category II

B. Use a smooth-surface ice scoop to dispense ice.

680, 863

Category II

Keep the ice scoop on a chain short enough the scoop cannot touch the floor, or keep

the scoop on a clean, hard surface when not in use.

680, 863

Category II

Do not store the ice scoop in the ice bin.

Category II

C. Do not store pharmaceuticals or medical solutions on ice intended for consumption; use

sterile ice to keep medical solutions cold, or use equipment specifically manufactured for

this purpose.

600, 863

Category IB

132

D. Machines that dispense ice are preferred to those that require ice to be removed from bins or

chests with a scoop.

687, 869

Category II

Limit access to ice-storage chests, and keep the container doors closed except when

removing ice.

863

Category II

Clean, disinfect, and maintain ice-storage chests on a regular basis.

Category II

Follow the manufacturer’s instructions for cleaning.

Category II

Use an EPA-registered disinfectant suitable for use on ice machines, dispensers, or

storage chests in accordance with label instructions.

Category II

If instructions and EPA-registered disinfectants suitable for use on ice machines are

not available, use a general cleaning/disinfecting regimen as outlined in Box 12.

863

Category II

Flush and clean the ice machines and dispensers if they have not been disconnected

before anticipated lengthy water disruptions.

Category II

G. Install proper air gaps where the condensate lines meet the waste lines.

Category II

H. Conduct microbiologic sampling of ice, ice chests, and ice-making machines and dispensers

where indicated during an epidemiologic investigation.

861–863

Category IB

Hydrotherapy Tanks and Pools

A. Drain and clean hydrotherapy equipment (e.g., Hubbard tanks, tubs, whirlpools, whirlpool

spas, or birthing tanks) after each patient’s use, and disinfect equipment surfaces and

components by using an EPA-registered product in accordance with the manufacturer’s

instructions.

Category II

B. In the absence of an EPA-registered product for water treatment, add sodium hypochlorite

to the water:

Maintain a 15-ppm chlorine residual in the water of small hydrotherapy tanks,

Hubbard tanks, and tubs.

889

Category II

Maintain a 2–5 ppm chlorine residual in the water of whirlpools and whirlpool

spas.

905

Category II

If the pH of the municipal water is in the basic range (e.g., when chloramine is used

as the primary drinking water disinfectant in the community), consult the facility

engineer regarding the possible need to adjust the pH of the water to a more acid level

before disinfection, to enhance the biocidal activity of chlorine.

894

Category II

C. Clean and disinfect hydrotherapy equipment after using tub liners.

Category II

D. Clean and disinfect inflatable tubs unless they are single-use equipment.

Category II

No recommendation is offered

regarding the use of antiseptic chemicals (e.g., chloramine-

T) in the water during hydrotherapy sessions.

Unresolved issue

Conduct a risk assessment of patients prior to their use of large hydrotherapy pools,

deferring patients with draining wounds or fecal incontinence from pool use until their

condition resolves.

Category II

G. For large hydrotherapy pools, use pH and chlorine residual levels appropriate for an indoor

pool as provided by local and state health agencies.

Category IC

(States)

No recommendation is offered

regarding the use in health care of whirlpools or spa

equipment manufactured for home or recreational use.

Unresolved issue

XI. Miscellaneous Medical Equipment Connected to Water Systems

A. Clean, disinfect, and maintain AER equipment according to the manufacturer’s instructions

and relevant scientific literature to prevent inadvertent contamination of endoscopes and

bronchoscopes with waterborne microorganisms.

911–915

Category IB

To rinse disinfected endoscopes and bronchoscopes, use water of the highest quality

practical for the system’s engineering and design (e.g., sterile water or

133

bacteriologically-filtered water [water filtered through 0.1–0.2-µm filters]).

912, 914, 915,

918

Category IB

Dry the internal channels of the reprocessed endoscope or bronchoscope using a

proven method (e.g., 70% alcohol followed by forced-air treatment) to lessen the

potential for the proliferation of waterborne microorganisms and to help prevent

biofilm formation.

671, 921, 923, 925, 928

Category IB

B. Use water that meets nationally recognized standards set by the EPA for drinking water

(<500 CFU/mL for heterotrophic plate count) for routine dental treatment output water.

935,

936, 943, 944

Category IB, IC

(EPA: 40 CFR 1 Part 141, Subpart G).

C. Take precautions to prevent waterborne contamination of dental unit water lines and

instruments.

After each patient, discharge water and air for a minimum of 20–30 seconds from any

dental device connected to the dental water system that enters the patient’s mouth

(e.g., handpieces, ultrasonic scalers, and air/water syringe).

936, 937

Category II

Consult with dental water-line manufacturers to 1) determine suitable methods and

equipment to obtain the recommended water quality; and 2) determine appropriate

methods for monitoring the water to ensure quality is maintained.

936, 946

Category II

Consult with the dental unit manufacturer on the need for periodic maintenance of

anti-retraction mechanisms.

937, 946

Category IB

E. Recommendations—Environmental Services

Cleaning and Disinfecting Strategies for Environmental Surfaces in Patient-Care Areas

A. Select EPA-registered disinfectants, if available, and use them in accordance with the

manufacturer’s instructions.

2, 974, 983

Category IB, IC

(EPA: 7 United States Code [USC] § 136 et

seq)

B. Do not use high-level disinfectants/liquid chemical sterilants for disinfection of either

noncritical instrument/devices or any environmental surfaces; such use is counter to label

instructions for these toxic chemicals.

951, 952, 961–964

Category IB, IC

(FDA: 21 CFR 801.5,

807.87.e)

C. Follow manufacturers’ instructions for cleaning and maintaining noncritical medical

equipment.

Category II

D. In the absence of a manufacturer’s cleaning instructions, follow certain procedures.

Clean noncritical medical equipment surfaces with a detergent/disinfectant. This may

be followed with an application of an EPA-registered hospital disinfectant with or

without a tuberculocidal claim (depending on the nature of the surface and the degree

of contamination), in accordance with disinfectant label instructions.

952

Category II

Do not use alcohol to disinfect large environmental surfaces.

951

Category II

Use barrier protective coverings as appropriate for noncritical equipment surfaces that

are 1) touched frequently with gloved hands during the delivery of patient care; 2)

likely to become contaminated with blood or body substances; or 3) difficult to clean

(e.g., computer keyboards).

936

Category II

Keep housekeeping surfaces (e.g., floors, walls, and tabletops) visibly clean on a regular

basis and clean up spills promptly.

954

Category II

Use a one-step process and an EPA-registered hospital disinfectant/detergent

designed for general housekeeping purposes in patient-care areas when 1) uncertainty

exists as to the nature of the soil on these surfaces [e.g., blood or body fluid

contamination versus routine dust or dirt]; or 2) uncertainty exists regarding the

presence or absence of multi-drug resistant organisms on such surfaces.

952, 983, 986, 987

Category II

134

Detergent and water are adequate for cleaning surfaces in nonpatient-care areas (e.g.,

administrative offices).

Category II

Clean and disinfect high-touch surfaces (e.g., doorknobs, bed rails, light switches, and

surfaces in and around toilets in patients’ rooms) on a more frequent schedule than

minimal touch housekeeping surfaces.

Category II

Clean walls, blinds, and window curtains in patient-care areas when they are visibly

dusty or soiled.

2, 971, 972, 982

Category II

Do not perform disinfectant fogging in patient-care areas.

2, 976

Category IB

G. Avoid large-surface cleaning methods that produce mists or aerosols or disperse dust in

patient-care areas.

9, 20, 109, 272

Category IB

H. Follow proper procedures for effective use of mops, cloths, and solutions.

Category II

Prepare cleaning solutions daily or as needed, and replace with fresh solution

frequently according to facility policies and procedures.

986, 987

Category II

Change the mop head at the beginning of the day and also as required by facility

policy, or after cleaning up large spills of blood or other body substances.

Category

Clean mops and cloths after use and allow to dry before reuse; or use single-use,

disposable mop heads and cloths.

971, 988–990

Category II

After the last surgical procedure of the day or night, wet vacuum or mop operating room

floors with a single-use mop and an EPA-registered hospital disinfectant.

Category IB

Do not use mats with tacky surfaces at the entrance to operating rooms or infection-control

suites.

Category IB

K. Use appropriate dusting methods for patient-care areas designated for immunocompromised

patients (e.g., HSCT patients):

9, 94, 986

Category IB

Wet-dust horizontal surfaces daily by moistening a cloth with a small amount of an

EPA-registered hospital detergent/disinfectant.

9, 94, 986

Category IB

Avoid dusting methods that disperse dust (e.g., feather-dusting).

Category IB

Keep vacuums in good repair, and equip vacuums with HEPA filters for use in areas with

patients at risk.

9, 94, 986, 994

Category IB

M. Close the doors of immunocompromised patients’ rooms when vacuuming, waxing, or

buffing corridor floors to minimize exposure to airborne dust.

9, 94, 994

Category IB

N. When performing low- or intermediate-level disinfection of environmental surfaces in

nurseries and neonatal units, avoid unnecessary exposure of neonates to disinfectant

residues on environmental surfaces by using EPA-registered disinfectants in accordance

with manufacturers’ instructions and safety advisories.

974, 995–997

Category IB, IC

(EPA: 7

USC § 136 et seq.)

Do not use phenolics or any other chemical germicide to disinfect bassinets or

incubators during an infant’s stay.

952, 995–997

Category IB

Rinse disinfectant-treated surfaces, especially those treated with phenolics, with

water.

995–997

Category IB

O. When using phenolic disinfectants in neonatal units, prepare solutions to correct

concentrations in accordance with manufacturers’ instructions, or use premixed

formulations.

974, 995–997

Category IB, IC

(EPA: 7 USC § 136 et seq.)

II.

Cleaning Spills of Blood and Body Substances

A. Promptly clean and decontaminate spills of blood or other potentially infectious

materials.

967, 998–1004

Category IB, IC

(OSHA: 29 CFR 1910.1030 §d.4.ii.A)

B. Follow proper procedures for site decontamination of spills of blood or blood-containing

body fluids.

967, 998–1004

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.ii.A)

Use protective gloves and other PPE appropriate for this task.

967

Category IC

(OSHA: 29 CFR 1910.1030 § d.3.i, ii)

135

If the spill contains large amounts of blood or body fluids, clean the visible matter

with disposable absorbent material, and discard the contaminated materials in

appropriate, labeled containment.

967, 1002, 1003, 1010, 1012

Category IC

(OSHA: 29 CFR

1910.1030 § d.4.iii.B)

Swab the area with a cloth or paper towels moderately wetted with disinfectant, and

allow the surface to dry.

967, 1010

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.ii.A)

C. Use EPA-registered hospital disinfectants labeled tuberculocidal or registered germicides on

the EPA Lists D and E (products with specific label claims for HIV or hepatitis B virus

[HBV]) in accordance with label instructions to decontaminate spills of blood and other

body fluids.

967, 1007, 1010

Category IC

(OSHA 29 CFR 1910.1030 § d.4.ii.A memorandum 2/28/97;

compliance document CPL 2-2.44D [11/99])

D. An EPA-registered sodium hypochlorite product is preferred, but if such products are not

available, generic versions of sodium hypochlorite solutions (e.g., household chlorine

bleach) may be used.

Use a 1:100 dilution (500–615 ppm available chlorine) to decontaminate nonporous

surfaces after cleaning a spill of either blood or body fluids in patient-care

settings.

1010, 1011

Category II

If a spill involves large amounts of blood or body fluids, or if a blood or culture spill

occurs in the laboratory, use a 1:10 dilution (5,000–6,150 ppm available chlorine) for

the first application of germicide before cleaning.

954, 1010

Category II

III. Carpeting and Cloth Furnishings

A. Vacuum carpeting in public areas of health-care facilities and in general patient-care areas

regularly with well-maintained equipment designed to minimize dust dispersion.

986

Category II

B. Periodically perform a thorough, deep cleaning of carpeting as determined by facility policy

by using a method that minimizes the production of aerosols and leaves little or no

residue.

111

Category II

C. Avoid use of carpeting in high-traffic zones in patient-care areas or where spills are likely

(e.g., burn therapy units, operating rooms, laboratories, and intensive care units).

111, 1023, 1028

Category IB

D. Follow proper procedures for managing spills on carpeting.

Spot-clean blood or body substance spills promptly.

967, 1010, 1011, 1032

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.ii.A, interpretation)

If a spill occurs on carpet tiles, replace any tiles contaminated by blood and body

fluids or body substances.

1032

Category IC

(OSHA 29 CFR 1910.1030 § d.4.ii interpretation)

Thoroughly dry wet carpeting to prevent the growth of fungi; replace carpeting that remains

wet after 72 hours.

9, 1026

Category IB

No recommendation is offered

regarding the routine use of fungicidal or bactericidal

treatments for carpeting in public areas of a health-care facility or in general patient-care

areas.

Unresolved issue

G. Do not use carpeting in hallways and patient rooms in areas housing immunosuppressed

patients (e.g., PE areas).

9, 111

Category IB

H. Avoid the use of upholstered furniture and furnishings in high-risk patient-care areas and in

areas with increased potential for body substance contamination (e.g., pediatrics units).

Category II

No recommendation is offered

regarding whether upholstered furniture and furnishings

should be avoided in general patient-care areas.

Unresolved issue

Maintain upholstered furniture in good repair.

Category II

Maintain the surface integrity of the upholstery by repairing tears and holes.

Category II

136

If upholstered furniture in a patient’s room requires cleaning to remove visible soil or

body substance contamination, move that item to a maintenance area where it can be

adequately cleaned with a process appropriate for the type of upholstery and the

nature of the soil.

Category II

IV. Flowers and Plants in Patient-Care Areas

A. Flowers and potted plants need not be restricted from areas for immunocompetent

patients.

515, 702, 1040, 1042

Category II

B. Designate care and maintenance of flowers and potted plants to staff not directly involved

with patient care.

702

Category II

C. If plant or flower care by patient-care staff is unavoidable, instruct the staff to wear gloves

when handling the plants and flowers and perform hand hygiene after glove removal.

702

Category II

Do not allow fresh or dried flowers, or potted plants in patient-care areas for

immunosuppressed patients.

9, 109, 515, 1046

Category II

V. Pest

Control

A. Develop pest-control strategies, with emphasis on kitchens, cafeterias, laundries, central

sterile supply areas, operating rooms, loading docks, construction activities, and other areas

prone to infestations.

1050, 1072, 1075

Category II

B. Install screens on all windows that open to the outside; keep screens in good repair.

1072

Category IB

C. Contract for routine pest control service by a credentialed pest-control specialist who will

tailor the application to the needs of a health-care facility.

1075

Category II

D. Place laboratory specimens (e.g., fixed sputum smears) in covered containers for overnight

storage.

1065, 1066

Category II

VI. Special

Pathogens

A. Use appropriate hand hygiene, PPE (e.g., gloves), and isolation precautions during cleaning

and disinfecting procedures.

5, 952, 1130, 1364

Category IB

B. Use standard cleaning and disinfection protocols to control environmental contamination

with antibiotic-resistant gram-positive cocci (e.g., methicillin-resistant

Staphylococcus

aureus

, vancomycin intermediate-resistant

Staphylococcus aureus

, or vancomycin-resistant

Enterococcus

[VRE] ).

5, 1116–1118

Category IB

Pay close attention to cleaning and disinfection of high-touch surfaces in patient-care

areas (e.g., bed rails, carts, bedside commodes, bedrails, doorknobs, or faucet

handles).

5, 1116–1118

Category IB

Ensure compliance by housekeeping staff with cleaning and disinfection procedures.

1116–1118

Category IB

Use EPA-registered hospital disinfectants appropriate for the surface to be disinfected

(e.g., either low- or intermediate-level disinfection) as specified by the manufacturers’

instructions.

974, 1106–1110, 1118

Category IB, IC

(EPA: 7 USC § 136 et seq.)

When contact precautions are indicated for patient care, use disposable patient-care

items (e.g., blood pressure cuffs) whenever possible to minimize cross-contamination

with multiple-resistant microorganisms.

1102

Category IB

Follow these same surface cleaning and disinfecting measures for managing the

environment of VRSA patients.

1110, 1116–1118

Category II

C. Environmental-surface culturing can be used to verify the efficacy of hospital policies and

procedures before and after cleaning and disinfecting rooms that house patients with VRE.

1084, 1087, 1088, 1092, 1096

Category II

137

Obtain prior approval from infection-control staff and the clinical laboratory before

performing environmental surface culturing.

Category II

Infection-control staff, with clinical laboratory consultation, must supervise all

environmental culturing.

Category II

D. Thoroughly clean and disinfect environmental and medical equipment surfaces on a regular

basis using EPA-registered disinfectants in accordance with manufacturers’ instructions.

952,

974, 1130, 1143

Category IB, IC

(EPA: 7 USC § 136 et seq.)

Advise families, visitors, and patients about the importance of hand hygiene to minimize the

spread of body substance contamination (e.g., respiratory secretions or fecal matter) to

surfaces.

952

Category II

Do not use high-level disinfectants (i.e., liquid chemical sterilants) on environmental

surfaces; such use is inconsistent with label instructions and because of the toxicity of the

chemicals.

2, 951, 952, 964

Category IC

(FDA: 21 CFR 801.5, 807.87.e)

G. Because no EPA-registered products are specific for inactivating

Clostridium difficile

spores, use hypochlorite-based products for disinfection of environmental surfaces in those

patient-care areas where surveillance and epidemiology indicate ongoing transmission of

difficile

952, 1130, 1141

Category II

No recommendation is offered

regarding the use of specific EPA-registered hospital

disinfectants with respect to environmental control of

C. difficile

Unresolved issue

Apply standard cleaning and disinfection procedures to control environmental

contamination with respiratory and enteric viruses in pediatric-care units and care areas for

immunocompromised patients.

986, 1158

Category IC

(EPA: 7 USC § 136 et seq.)

Clean surfaces that have been contaminated with body substances; perform low- to

intermediate-level disinfection on cleaned surfaces with an EPA-registered disinfectant in

accordance with the manufacturer’s instructions.

967, 974, 1158

Category IC

(OSHA: 29 CFR

1910.1030 § d.4.ii.A; EPA: 7 USC § 136 et seq.)

K. Use disposable barrier coverings as appropriate to minimize surface contamination.

Category II

Develop and maintain cleaning and disinfection procedures to control environmental

contamination with agents of Creutzfeldt-Jakob disease (CJD), for which no EPA-registered

product exists.

Category II

In the absence of contamination with central nervous system tissue, extraordinary

measures (e.g., use of 2N sodium hydroxide [NaOH] or applying full-strength sodium

hypochlorite) are not needed for routine cleaning or terminal disinfection of a room

housing a confirmed or suspected CJD patient.

951, 1199

Category II

After removing gross tissue from the surface, use either 1N NaOH or a sodium

hypochlorite solution containing approximately 10,000–20,000 ppm available

chlorine (dilutions of 1:5 to 1:3 v/v, respectively, of U.S. household chlorine bleach;

contact the manufacturers of commercially available sodium hypochlorite products

for advice) to decontaminate operating room or autopsy surfaces with central nervous

system or cerebral spinal fluid contamination from a diagnosed or suspected CJD

patient.

951, 1170, 1188, 1191, 1197–1199, 1201

Category II

The contact time for the chemical used during this process should be 30 min–1

hour.

1191, 1197, 1201

Blot up the chemical with absorbent material and rinse the treated surface

thoroughly with water.

Discard the used, absorbent material into appropriate waste containment.

Use disposable, impervious covers to minimize body substance contamination to

autopsy tables and surfaces.

1197, 1201

Category IB

138

M. Use standard procedures for containment, cleaning, and decontamination of blood spills on

surfaces as previously described (Environmental Services: II).

967

Category IC

(OSHA: 29

CFR 1910.1030 §d.4.ii.A)

Wear PPE appropriate for a surface decontamination and cleaning task.

967, 1199

Category IC

(OSHA 29 CFR 1910.1030 §d.3.i, ii)

Discard used PPE by using routine disposal procedures or decontaminate reusable

PPE as appropriate.

967, 1199

Category IC

(OSHA 29 CFR 1910.1030 §d.3.viii)

F. Recommendations—Environmental Sampling

I. General

Information

A. Do not conduct random, undirected microbiologic sampling of air, water, and

environmental surfaces in health-care facilities.

2, 1214

Category IB

B. When indicated, conduct microbiologic sampling as part of an epidemiologic investigation

or during assessment of hazardous environmental conditions to detect contamination and

verify abatement of a hazard.

2, 1214

Category IB

C. Limit microbiologic sampling for quality assurance purposes to 1) biological monitoring of

sterilization processes; 2) monthly cultures of water and dialysate in hemodialysis units; and

3) short-term evaluation of the impact of infection-control measures or changes in infection-

control protocols.

2, 1214

Category IB

II.

Air, Water, and Environmental-Surface Sampling

A. When conducting any form of environmental sampling, identify existing comparative

standards and fully document departures from standard methods.

945, 1214, 1223, 1224, 1238

Category II

B. Select a high-volume air sampling device if anticipated levels of microbial airborne

contamination are expected to be low.

290, 1218, 1223, 1224

Category II

C. Do not use settle plates to quantify the concentration of airborne fungal spores.

290

Category II

D. When sampling water, choose growth media and incubation conditions that will facilitate

the recovery of waterborne organisms.

945

Category II

When using a sample/rinse method for sampling an environmental surface, develop and

document a procedure for manipulating the swab, gauze, or sponge in a reproducible

manner so that results are comparable.

1238

Category II

When environmental samples and patient specimens are available for comparison, perform

the laboratory analysis on the recovered microorganisms down to the species level at a

minimum and beyond the species level if possible.

1214

Category II

G. Recommendations—Laundry and Bedding

I. Employer

Responsibilities

A. Employers must launder workers’ personal protective garments or uniforms that are

contaminated with blood or other potentially infectious materials.

967

Category IC

(OSHA:

29 CFR 1910.1030 § d.3.iv)

139

II.

Laundry Facilities and Equipment

A. Maintain the receiving area for contaminated textiles at negative pressure compared with

the clean areas of the laundry in accordance with AIA construction standards in effect

during the time of facility construction.

120, 1260–1262

Category IC

(AIA: 7.23.B1, B2)

B. Ensure that laundry areas have handwashing facilities and products and appropriate PPE

available for workers.

120, 967

Category IC

(

AIA: 7.23.D4; OSHA: 29 CFR 1910.1030 § d.2.iii)

C. Use and maintain laundry equipment according to manufacturers’ instructions.

1250, 1263

Category II

D. Do not leave damp textiles or fabrics in machines overnight.

1250

Category II

Disinfection of washing and drying machines in residential care is not needed as long as

gross soil is removed before washing and proper washing and drying procedures are used.

Category II

III. Routine Handling of Contaminated Laundry

A. Handle contaminated textiles and fabrics with minimum agitation to avoid contamination of

air, surfaces, and persons.

6, 967, 1258, 1259

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.iv)

B. Bag or otherwise contain contaminated textiles and fabrics at the point of use.

967

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.iv)

Do not sort or prerinse contaminated textiles or fabrics in patient-care areas.

967

Category IC

(OSHA: 29 CFR 1910.1030 §d.4.iv)

Use leak-resistant containment for textiles and fabrics contaminated with blood or

body substances.

967, 1258

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.iv)

Identify bags or containers for contaminated textiles with labels, color coding, or

other alternative means of communication as appropriate.

967

Category IC

(OSHA:

29 CFR 1910.1030 § d.4.iv)

C. Covers are not needed on contaminated textile hampers in patient-care areas.

Category II

D. If laundry chutes are used, ensure that they are properly designed, maintained, and used in a

manner to minimize dispersion of aerosols from contaminated laundry.

1253, 1267–1270

Category IC

(AAMI: ANSI/AAMI ST65:2000)

Ensure that laundry bags are closed before tossing the filled bag into the chute.

Category II

Do not place loose items in the chute.

Category II

Establish a facility policy to determine when textiles or fabrics should be sorted in the

laundry facility (i.e., before or after washing).

1271, 1272

Category II

IV. Laundry

Process

A. If hot-water laundry cycles are used, wash with detergent in water >160°F (>71°C) for >25

minutes.

2, 120

Category IC

(AIA: 7.31.E3)

No recommendation is offered

regarding a hot-water temperature setting and cycle

duration for items laundered in residence-style health-care facilities.

Unresolved issue

C. Follow fabric-care instructions and special laundering requirements for items used in the

facility.

1278

Category II

D. Choose chemicals suitable for low-temperature washing at proper use concentration if low-

temperature (<160°F [<71°C]) laundry cycles are used.

1247, 1281–1285

Category II

Package, transport, and store clean textiles and fabrics by methods that will ensure their

cleanliness and protect them from dust and soil during interfacility loading, transport, and

unloading.

Category II

Microbiologic Sampling of Textiles

A. Do not conduct routine microbiological sampling of clean textiles.

2, 1286

Category IB

140

B. Use microbiological sampling during outbreak investigations if epidemiologic evidence

suggests a role for health-care textiles and clothing in disease transmission.

1286

Category

VI. Special Laundry Situations

A. Use sterilized textiles, surgical drapes, and gowns for situations requiring sterility in patient

care.

Category IB

B. Use hygienically clean textiles (i.e., laundered, but not sterilized) in neonatal intensive care

units.

997, 1288

Category IB

C. Follow manufacturers’ recommendations for cleaning fabric products including those with

coated or laminated surfaces.

Category II

D. Do not use dry cleaning for routine laundering in health-care facilities.

1289–1291

Category

Use caution when considering the use of antimicrobial mattresses, textiles, and clothing as

replacements for standard bedding and other fabric items; EPA has not approved public

health claims asserting protection against human pathogens for treated articles.

1306

Category II

No recommendation is offered

regarding using disposable fabrics and textiles versus

durable goods.

Unresolved issue

VII. Mattresses and Pillows

A. Keep mattresses dry; discard them if they become and remain wet or stained, particularly in

burn units.

1310–1315

Category IB

B. Clean and disinfect mattress covers using EPA-registered disinfectants, if available, that are

compatible with the cover materials to prevent the development of tears, cracks, or holes in

the cover.

1310–1315

Category IB

C. Maintain the integrity of mattress and pillow covers.

Category II

Replace mattress and pillow covers if they become torn or otherwise in need of repair.

Category II

Do not stick needles into the mattress through the cover.

Category II

D. Clean and disinfect moisture-resistant mattress covers between patients using an EPA-

registered product, if available.

1310–1315

Category IB

If using a mattress cover completely made of fabric, change these covers and launder

between patients.

1310–1315

Category IB

Launder pillow covers and washable pillows in the hot-water cycle between patients or

when they become contaminated with body substances.

1315

Category IB

VIII. Air-Fluidized Beds

A. Follow manufacturers’ instructions for bed maintenance and decontamination.

Category

B. Change the polyester filter sheet at least weekly or as indicated by the manufacturer.

1317, 1318,

1322, 1323

Category II

C. Clean and disinfect the polyester filter sheet thoroughly, especially between patients, using

an EPA-registered product, if available.

1317, 1318, 1322, 1323

Category IB

D. Consult the facility engineer to determine the proper location of air-fluidized beds in

negative-pressure rooms.

1326

Category II

141

H. Recommendations—Animals in Health-Care Facilities

General Infection-Control Measures for Animal Encounters

A. Minimize contact with animal saliva, dander, urine, and feces.

1365–1367

Category II

B. Practice hand hygiene after any animal contact.

2, 1364

Category IB

Wash hands with soap and water, especially if hands are visibly soiled.

1364

Category IB

Use either soap and water or alcohol-based hand rubs when hands are not visibly

soiled.

1364

Category IB

II.

Animal-Assisted Activities, Animal-Assisted Therapy, and Resident Animal Programs

A. Avoid selection of nonhuman primates and reptiles in animal-assisted activities, animal-

assisted therapy, or resident animal programs.

1360–1362

Category IB

B. Enroll animals that are fully vaccinated for zoonotic diseases and that are healthy, clean,

well-groomed, and negative for enteric parasites or otherwise have completed recent

antihelminthic treatment under the regular care of a veterinarian.

1349, 1360

Category II

C. Enroll animals that are trained with the assistance or under the direction of individuals who

are experienced in this field.

1360

Category II

D. Ensure that animals are handled by persons trained in providing activities or therapies

safely, and who know the animals’ health status and behavior traits.

1349, 1360

Category II

Take prompt action when an incident of biting or scratching by an animal occurs during an

animal-assisted activity or therapy.

Remove the animal permanently from these programs.

1360

Category II

Report the incident promptly to appropriate authorities (e.g., infection-control staff,

animal program coordinator, or local animal control).

1360

Category II

Promptly clean and treat scratches, bites, or other accidental breaks in the skin.

Category II

Perform an ICRA and work actively with the animal handler prior to conducting an animal-

assisted activity or therapy to determine if the session should be held in a public area of the

facility or in individual patient rooms.

1349, 1360

Category II

G. Take precautions to mitigate allergic responses to animals.

Category II

Minimize shedding of animal dander by bathing animals <24 hours before a visit.

1360

Category II

Groom animals to remove loose hair before a visit, or using a therapy animal cape.

1358

Category II

H. Use routine cleaning protocols for housekeeping surfaces after therapy sessions.

Category II

Restrict resident animals, including fish in fish tanks, from access to or placement in

patient-care areas, food preparation areas, dining areas, laundry, central sterile supply areas,

sterile and clean supply storage areas, medication preparation areas, operating rooms,

isolation areas, and PE areas.

Category II

Establish a facility policy for regular cleaning of fish tanks, rodent cages, bird cages, and

any other animal dwellings and assign this cleaning task to a nonpatient-care staff member;

avoid splashing tank water or contaminating environmental surfaces with animal bedding.

Category II

III. Protective Measures for Immunocompromised Patients

A. Advise patients to avoid contact with animal feces and body fluids such as saliva, urine, or

solid litter box material.

Category II

142

B. Promptly clean and treat scratches, bites, or other wounds that break the skin.

Category

C. Advise patients to avoid direct or indirect contact with reptiles.

1340

Category IB

D. Conduct a case-by-case assessment to determine if animal-assisted activities or animal-

assisted therapy programs are appropriate for immunocompromised patients.

1349

Category

No recommendation is offered

regarding permitting pet visits to terminally ill

immunosuppressed patients outside their PE units.

Unresolved issue

IV. Service

Animals

A. Avoid providing access to nonhuman primates and reptiles as service animals.

1340, 1362

Category IB

B. Allow service animals access to the facility in accordance with the Americans with

Disabilities Act of 1990, unless the presence of the animal creates a direct threat to other

persons or a fundamental alteration in the nature of services.

1366, 1376

Category IC

(U.S.

Department of Justice: 28 CFR § 36.302)

C. When a decision must be made regarding a service animal’s access to any particular area of

the health-care facility, evaluate the service animal, the patient, and the health-care situation

on a case-by-case basis to determine whether significant risk of harm exists and whether

reasonable modifications in policies and procedures will mitigate this risk.

1376

Category

(Justice: 28 CFR § 36.208 and App.B)

D. If a patient must be separated from his or her service animal while in the health-care facility

1) ascertain from the person what arrangements have been made for supervision or care of

the animal during this period of separation; and 2) make appropriate arrangements to

address the patient’s needs in the absence of the service animal.

Category II

Animals as Patients in Human Health-Care Facilities

A. Develop health-care facility policies to address the treatment of animals in human health-

care facilities.

Use the multidisciplinary team approach to policy development, including public

media relations in order to disclose and discuss these activities.

Category II

Exhaust all veterinary facility, equipment, and instrument options before undertaking

the procedure.

Category II

Ensure that the care of the animal is supervised by a licensed veterinarian.

Category II

B. When animals are treated in human health-care facilities, avoid treating animals in

operating rooms or other patient-care areas where invasive procedures are performed (e.g.,

cardiac catheterization laboratories, or invasive nuclear medicine areas).

Category II

C. Schedule the animal procedure for the last case of the day for the area, at a time when

human patients are not scheduled to be in the vicinity.

Category II

D. Adhere

strictly

to standard precautions.

Category II

Clean and disinfect environmental surfaces thoroughly using an EPA-registered product in

the room after the animal is removed.

Category II

Allow sufficient ACH to clean the air and help remove airborne dander, microorganisms,

and allergens [Appendix B, Table B.1.]).

Category II

G. Clean and disinfect using EPA-registered products or sterilize equipment that has been in

contact with animals, or use disposable equipment.

Category II

H. If reusable medical or surgical instruments are used in an animal procedure, restrict future

use of these instruments to animals only.

Category II

143

VI. Research Animals in Health-Care Facilities

A. Use animals obtained from quality stock, or quarantine incoming animals to detect zoonotic

diseases.

Category II

B. Treat sick animals or remove them from the facility.

Category II

C. Provide prophylactic vaccinations, as available, to animal handlers and contacts at high risk.

Category II

D. Ensure proper ventilation through appropriate facility design and location.

1395

Category

(U.S. Department of Agriculture [USDA]: 7 USC 2131)

Keep animal rooms at negative pressure relative to corridors.

1395

Category IC

(USDA: 7 USC 2131)

Prevent air in animal rooms from recirculating elsewhere in the health-care

facility.

1395

Category IC

(USDA: 7 USC 2131)

Keep doors to animal research rooms closed.

Category II

Restrict access to animal facilities to essential personnel.

Category II

G. Establish employee occupational health programs specific to the animal research facility,

and coordinate management of postexposure procedures specific for zoonoses with

occupational health clinics in the health-care facility.

1013, 1378

Category IC

(U.S. Department

of Health and Human Services [DHHS]: BMBL; OSHA: 29 CFR 1910.1030.132-139)

H. Document standard operating procedures for the unit.

1013

Category IC

(DHHS: BMBL)

Conduct routine employee training on worker safety issues relevant to the animal research

facility (e.g., working safely with animals and animal handling).

1013, 1393

Category IC

(DHHS: BMBL; OSHA: 29 CFR 1910.1030.132-139)

Use precautions to prevent the development of animal-induced asthma in animal

workers.

1013

Category IC

(DHHS: BMBL)

I. Recommendations—Regulated Medical Waste

Categories of Regulated Medical Waste

A. Designate the following as major categories of medical waste that require special handling

and disposal precautions: 1) microbiology laboratory wastes [e.g., cultures and stocks of

microorganisms]; 2) bulk blood, blood products, blood, and bloody body fluid specimens;

3) pathology and anatomy waste; and 4) sharps [e.g., needles and scalpels].

Category II

B. Consult federal, state, and local regulations to determine if other waste items are considered

regulated medical wastes.

967, 1407, 1408

Category IC

(States; Authorities having jurisdiction [AHJ];

OSHA: 29 CFR 1910.1030 §g.2.1; U.S. Department of Transportation [DOT]: 49 CFR 171-180; U.S. Postal Service: CO23.8)

II.

Disposal Plan for Regulated Medical Wastes

A. Develop a plan for the collection, handling, predisposal treatment, and terminal disposal of

regulated medical wastes.

967, 1409

Category IC

(States; AHJ; OSHA: 29 CFR 1910.1030 §g.2.i;)

B. Designate a person or persons to be responsible for establishing, monitoring, reviewing, and

administering the plan.

Category II

III. Handling, Transporting, and Storing Regulated Medical Wastes

A. Inform personnel involved in the handling and disposal of potentially infective waste of the

possible health and safety hazards; ensure that they are trained in appropriate handling and

disposal methods.

967

Category IC

(OSHA: 29 CFR 1910.1030 § g.2.i)

B. Manage the handling and disposal of regulated medical wastes generated in isolation areas

by using the same methods as for regulated medical wastes from other patient-care areas.

Category II

C. Use proper sharps disposal strategies.

967

Category IC

(OSHA: 29 CFR 1910.1030 § d.4.iii.A)

144

Use a sharps container capable of maintaining its impermeability after waste

treatment to avoid subsequent physical injuries during final disposal.

967

Category

(OSHA: 29 CFR 1910.1030 § d.4.iii.A)

Place disposable syringes with needles, including sterile sharps that are being

discarded, scalpel blades, and other sharp items into puncture-resistant containers

located as close as practical to the point of use.

967

Category IC

(OSHA: 29 CFR

1910.1030 § d.4.iii.A)

Do not bend, recap, or break used syringe needles before discarding them into a

container.

6, 967, 1415

Category IC

(OSHA: 29 CFR 1910.1030 § d.2.vii and § d.2.vii.A)

D. Store regulated medical wastes awaiting treatment in a properly ventilated area that is

inaccessible to vertebrate pests; use waste containers that prevent the development of

noxious odors.

Category IC

(States; AHJ)

If treatment options are not available at the site where the medical waste is generated,

transport regulated medical wastes in closed, impervious containers to the on-site treatment

location or to another facility for treatment as appropriate.

Category IC

(States; AHJ)

IV. Treatment and Disposal of Regulated Medical Wastes

A. Treat regulated medical wastes by using a method (e.g., steam sterilization, incineration,

interment, or an alternative treatment technology) approved by the appropriate authority

having jurisdiction (AHJ) (e.g., states, Indian Health Service [IHS], Veterans Affairs [VA])

before disposal in a sanitary landfill.

Category IC

(States, AHJ)

B. Follow precautions for treating microbiological wastes (e.g., amplified cultures and stocks

of microorganisms).

1013

Category IC

(DHHS: BMBL)

Biosafety level 4 laboratories must inactivate microbiological wastes in the laboratory

by using an approved inactivation method (e.g., autoclaving) before transport to and

disposal in a sanitary landfill.

1013

Category IC

(DHHS: BMBL)

Biosafety level 3 laboratories must inactivate microbiological wastes in the laboratory

by using an approved inactivation method (e.g., autoclaving) or incinerate them at the

facility before transport to and disposal in a sanitary landfill.

1013

Category IC

(DHHS: BMBL)

C. Biosafety levels 1 and 2 laboratories should develop strategies to inactivate amplified

microbial cultures and stocks onsite by using an approved inactivation method (e.g.,

autoclaving) instead of packaging and shipping untreated wastes to an offsite facility for

treatment and disposal.

1013, 1419–1421

Category II

D. Laboratories that isolate select agents from clinical specimens must comply with federal

regulations for the receipt, transfer, management, and appropriate disposal of these

agents.

1412

Category IC

(DHHS: 42 CFR 73 § 73.6)

Sanitary sewers may be used for the safe disposal of blood, suctioned fluids, ground tissues,

excretions, and secretions, provided that local sewage discharge requirements are met and

that the state has declared this to be an acceptable method of disposal.

1414

Category II

Special Precautions for Wastes Generated During Care of Patients with Rare Diseases

A. When discarding items contaminated with blood and body fluids from VHF patients,

contain these regulated medical wastes with minimal agitation during handling.

6, 203

Category II

B. Manage properly contained wastes from areas providing care to VHF patients in accordance

with recommendations for other isolation areas (Regulated Medical Waste: III B).

2, 6, 203

Category II

C. Decontaminate bulk blood and body fluids from VHF patients using approved inactivation

methods (e.g., autoclaving or chemical treatment) before disposal.

6, 203

Category IC, II

(States; AHJ)

145

D. When discarding regulated medical waste generated during the routine (i.e., non-surgical)

care of CJD patients, contain these wastes and decontaminate them using approved

inactivation methods (e.g., autoclaving or incineration) appropriate for the medical waste

category (e.g., blood, sharps, pathological waste).

2, 6, 948, 1199

Category IC, II

(States; AHJ)

Incinerate medical wastes (e.g., central nervous system tissues or contaminated disposable

materials) from brain autopsy or biopsy procedures of diagnosed or suspected CJD

patients.

1197, 1201

Category IB

Part III. References

Note: The bold item in parentheses indicated the citation number or the location of this reference
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CDC. Guidelines for prevention of nosocomial pneumonia. MMWR 1997;46(No. RR-1):1–79.

(34)

CDC. Guidelines for preventing the transmission of

Mycobacterium tuberculosis

in health-care

facilities. MMWR 1994;43(No. RR-13):1–132.

(318)

CDC. Recommendations for preventing the spread of vancomycin resistance. Recommendations of

the Hospital Infection Control Practices Advisory Committee (HICPAC).

MMWR 1995;44(No. RR-12):1–

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(36)

Garner JS, Hospital Infection Control Practices Advisory Committee. Guideline for isolation

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Epidemiol 1999;20:247–80.

(396)

CDC. USPHS/IDSA guidelines for the prevention of opportunistic infections in persons infected with

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CDC. CDC/IDSA/ASBMT guidelines for the prevention of opportunistic infections in

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Garner JS. The CDC Hospital Infection Control Practice Advisory Committee. Am J Infect Control

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11.

Bennett JV, Brachman PS, eds. The inanimate environment. In: Rhame FS. Hospital Infections, 4

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Philadelphia, PA: Lippincott-Raven, 1998;299–324.

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Weber DJ, Rutala WA. Environmental issues and nosocomial infections. In: Wenzel RP, ed. Prevention and

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13.

Greene VW. Microbiological contamination control in hospitals. Hospitals JAHA 1969;43:78–88.

14.

American Hospital Association. Hospital statistics, 2000 ed.Historical trends in utilization, personnel, and

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McKee B. Neither bust nor boom. Architecture 1998. Available at:

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Sarubbi FA Jr, Kopf BB, Wilson NO, McGinnis MR, Rutala WA. Increased recovery of

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from respiratory specimens during hospital construction. Am Rev Respir Dis 1982;125:33–8.

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Arnow PM, Sadigh MC, Weil D, Chudy R. Endemic and epidemic aspergillosis associated with

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Joly JR. Monitoring for the presence of

Legionella

: where, when, and how? In: Barbaree

JM, Breiman RF, Dufour AP, eds.

Legionella

: current status and emerging perspectives. Washington,

DC: American Society for Microbiology Press, 1993;211–6.

1460.

(Appendix; 7)

Brenner DJ, Feeley JC, Weaver RE. Family VII.

Legionellaceae

. In: Krieg NR, Holt JG,

eds. Bergey’s manual of systemic bacteriology, volume 1. Baltimore, MD: Williams & Wilkins,

1984;279–88.

1461.

(Appendix; 8)

Katz SM, Hammel JM. The effect of drying, heat, and pH on the survival of

Legionella

pneumophila

. Ann Clin Lab Sci 1987;17:150–6.

1462.

(Box 2)

Alary MA, Joly JR. Comparison of culture methods and an immunofluorescence assay for the

detection of

Legionella pneumophila

in domestic hot water devices. Curr Microbiol 1992;25:19–25.

1463.

(Box 2)

Vickers RM, Stout JE, Yu VL. Failure of a diagnostic monoclonal immunofluorescent reagent

to detect

Legionella

pneumophila

in environmental samples. Appl Environ Microbiol 1990;56:2912–4.

1464.

(Box 2)

Flournoy DJ, Belobraydic KA, Silberg SL, Lawrence CH, Guthrie PJ. False postive

Legionella

pneumophila

direct immunofluorscence monoclonal antibody test caused by

Bacillus cereus

spores. Diag

Microbiol Infect Dis 1988;9:123–5.

1465.

(Box 2)

Bej AK, Majbubani MH, Atlas RM. Detection of viable

Legionella

pneumophila

in water by

polymerase chain reaction and gene probe methods. Appl Environ Microbiol 1991;57:597–600.

1466.

Schulze-Röbbecke R, Jung KD, Pullman H, Hundgeburth J. Control of

Legionella

pneumophila

in a

hospital hot water system. Zbl Hyg 1990;190:84–100.

1467.

Colbourne JS, Pratt DJ, Smith MG, Fisher-Hoch SP, Harper D. Water fittings as sources of

Legionella

pneumophila

in a hospital plumbing system. Lancet 1984;1:210–3.

1468.

U.S. Environmental Protection Agency. National interim primary drinking water regulations: control of

trihalomethanes in drinking water: final rules. Federal Register 1979;44:68624–705.

1469.

U.S. Environmental Protection Agency. National interim primary drinking water regulations:

Trihalomethanes. Federal Register 1983;48:8406–14.

201

Part IV. Appendices

Appendix A. Glossary of Terms

Acceptable indoor air quality:

air in which there are no known contaminants at harmful

concentrations as determined by knowledgeble authorities and with which a substantial majority (>80%)

of the people exposed do not express dissatisfaction.

ACGIH:

American Conference of Governmental Industrial Hygienists.

Action level:

the concentration of a contaminant at which steps should be taken to interrupt the trend

toward higher, unacceptable levels.

Aerosol:

particles of respirable size generated by both humans and environmental sources and that

have the capability of remaining viable and airborne for extended periods in the indoor environment.

AIA:

American Institute of Architects, a professional group responsible for publishing the

Guidelines

for Design and Construction of Hospitals and Healthcare Facilities

, a consensus document for design

and construction of health-care facilities endorsed by the U.S. Department of Health and Human

Services, health-care professionals, and professional organizations.

Air changes per hour (ACH):

the ratio of the volume of air flowing through a space in a certain

period of time (the airflow rate) to the volume of that space (the room volume). This ratio is expressed

as the number of air changes per hour (ACH).

Air mixing:

the degree to which air supplied to a room mixes with the air already in the room, usually

expressed as a mixing factor. This factor varies from 1 (for perfect mixing) to 10 (for poor mixing). It

is used as a multiplier to determine the actual airflow required (i.e., the recommended ACH multiplied

by the mixing factor equals the actual ACH required).

Airborne transmission:

a means of spreading infection when airborne droplet nuclei (small particle

residue of evaporated droplets <5 µm in size containing microorganisms that remain suspended in air

for long periods of time) are inhaled by the susceptible host.

Air-cleaning system:

a device or combination of devices applied to reduce the concentration of

airborne contaminants (e.g., microorganisms, dusts, fumes, aerosols, other particulate matter, and

gases).

Air conditioning:

the process of treating air to meet the requirements of a conditioned space by

controlling its temperature, humidity, cleanliness, and distribution.

Allogeneic:

non-twin, non-self. The term refers to transplanted tissue from a donor closely matched to

a recipient but not related to that person.

Ambient air:

the air surrounding an object.

Anemometer:

a flow meter which measures the wind force and velocity of air. An anemometer is

often used as a means of determining the volume of air being drawn into an air sampler.

Anteroom:

a small room leading from a corridor into an isolation room. This room can act as an

airlock, preventing the escape of contaminants from the isolation room into the corridor.

ASHE:

American Society for Healthcare Engineering, an association affiliated with the American

Hospital Association.

ASHRAE:

American Society of Heating, Refrigerating, and Air-Conditioning Engineers Inc.

Autologous:

self. The term refers to transplanted tissue whose source is the same as the recipient, or

an identical twin.

Automated cycler:

a machine used during peritoneal dialysis which pumps fluid into and out of the

patient while he/she sleeps.

Biochemical oxygen demand (BOD):

a measure of the amount of oxygen removed from aquatic

environments by aerobic microorganisms for their metabolic requirements. Measurement of BOD is

used to determine the level of organic pollution of a stream or lake. The greater the BOD, the greater

202

the degree of water pollution. The term is also referred to as Biological Oxygen Demand (BOD).

Biological oxygen demand (BOD):

an indirect measure of the concentration of biologically

degradable material present in organic wastes (pertaining to water quality). It usually reflects the

amount of oxygen consumed in five days by biological processes breaking down organic waste (BOD5).

Biosafety level:

a combination of microbiological practices, laboratory facilities, and safety equipment

determined to be sufficient to reduce or prevent occupational exposures of laboratory personnel to the

microbiological agents they work with. There are four biosafety levels based on the hazards associated

with the various microbiological agents.

BOD5:

the amount of dissolved oxygen consumed in five days by biological processes breaking down

organic matter.

Bonneting:

a floor cleaning method for either carpeted or hard surface floors that uses a circular

motion of a large fibrous disc to lift and remove soil and dust from the surface.

Capped spur:

a pipe leading from the water recirculating system to an outlet that has been closed off

(“capped”). A capped spur cannot be flushed, and it might not be noticed unless the surrounding wall is

removed.

CFU/m

colony forming units per cubic meter (of air).

Chlamydospores:

thick-walled, typically spherical or ovoid resting spores asexually produced by

certain types of fungi from cells of the somatic hyphae.

Chloramines:

compounds containing nitrogen, hydrogen, and chlorine. These are formed by the

reaction between hypochlorous acid (HOCl) and ammonia (NH

) and/or organic amines in water. The

formation of chloramines in drinking water treatment extends the disinfecting power of chlorine. The

term is also referred to as Combined Available Chlorine.

Cleaning:

the removal of visible soil and organic contamination from a device or surface, using either

the physical action of scrubbing with a surfactant or detergent and water, or an energy-based process

(e.g., ultrasonic cleaners) with appropriate chemical agents.

Coagulation-flocculation:

coagulation is the clumping of particles that results in the settling of

impurities. It may be induced by coagulants (e.g., lime, alum, and iron salts). Flocculation in water and

wastewater treatment is the agglomeration or clustering of colloidal and finely-divided suspended matter

after coagulation by gentle stirring by either mechanical or hydraulic means, such that they can be

separated from water or sewage.

Commissioning (a room):

testing a system or device to ensure that it meets the pre-use specifications

as indicated by the manufacturer or predetermined standard, or air sampling in a room to establish a pre-

occupancy baseline standard of microbial or particulate contamination. The term is also referred to as

benchmarking at 77°F (25°C).

Completely packaged:

functionally packaged, as for laundry.

Conidia:

asexual spores of fungi borne externally.

Conidiophores:

specialized hyphae that bear conidia in fungi.

Conditioned space:

that part of a building that is heated or cooled, or both, for the comfort of the

occupants.

Contaminant:

an unwanted airborne constituent that may reduce the acceptibility of air.

Convection:

the transfer of heat or other atmospheric properties within the atmosphere or in the

airspace of an enclosure by the circulation of currents from one region to another, especially by such

motion directed upward.

Cooling tower:

a structure engineered to receive accumulated heat from ventilation systems and

equipment and transfer this heat to water, which then releases the stored heat to the atmosphere through

evaporative cooling.

Critical item (medical instrument):

a medical instrument or device that contacts normally sterile

areas of the body or enters the vascular system. There is a high risk of infection from such devices if

they are microbiologically contaminated prior to use. These devices must be sterilized before use.

Dead legs:

areas in the water system where water stagnates. A dead leg is a pipe or spur, leading from

the water recirculating system to an outlet that is used infrequently, resulting in inadequate flow of

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water from the recirculating system to the outlet. This inadequate flow reduces the perfusion of heat or

chlorine into this part of the water distribution system, thereby adversely affecting the disinfection of the

water system in that area.

Deionization:

removal of ions from water by exchange with other ions associated with fixed charges

on a resin bed. Cations are usually removed and H

ions are exchanged; OH

ions are exchanged for

anions.

Detritis:

particulate matter produced by or remaining after the wearing away or disintegration of a

substance or tissue.

Dew point:

the temperature at which a gas or vapor condenses to form a liquid; the point at which

moisture begins to condense out of the air. At dew point, air is cooled to the point where it is at 100%

relative humidity or saturation.

Dialysate:

the aqueous electrolyte solution, usually containing dextrose, used to make a concentration

gradient between the solution and blood in the hemodialyzer (dialyzer).

Dialyzer:

a device that consists of two compartments (blood and dialysate) separated by a

semipermeable membrane. A dialyzer is usually referred to as an artificial kidney.

Diffuser:

the grille plate that disperses the air stream coming into the conditioned air space.

Direct transmission:

involves direct body surface-to-body surface contact and physical transfer of

microorganisms between a susceptible host and an infected/colonized person, or exposure to cloud of

infectious particles within 3 feet of the source; the aerosolized particles are >5 µm in size.

Disability:

as defined by the Americans with Disabilities Act, a disability is any physical or mental

impairment that substantially limits one or more major life activities, including but not limited to

walking, talking, seeing, breathing, hearing, or caring for oneself.

Disinfection:

a generally less lethal process of microbial inactivation (compared to sterilization) that

eliminates virtually all recognized pathogenic microorganisms but not necessarily all microbial forms

(e.g., bacterial spores).

Drain pans:

pans that collect water within the HVAC system and remove it from the system.

Condensation results when air and steam come together.

Drift:

circulating water lost from the cooling tower in the form as liquid droplets entrained in the

exhaust air stream (i.e., exhaust aerosols from a cooling tower).

Drift eliminators:

an assembly of baffles or labyrinth passages through which the air passes prior to its

exit from the cooling tower. The purpose of a drift eliminator is to remove entrained water droplets

from the exhaust air.

Droplets:

particles of moisture, such as are generated when a person coughs or sneezes, or when water

is converted to a fine mist by a device such as an aerator or shower head. These particles may contain

infectious microorganisms. Intermediate in size between drops and droplet nuclei, these particles tend

to quickly settle out from the air so that any risk of disease transmission is generally limited to persons

in close proximity to the droplet source.

Droplet nuclei:

sufficiently small particles (1–5 µm in diameter) that can remain airborne indefinitely

and cause infection when a susceptible person is exposed at or beyond 3 feet of the source of these

particles.

Dual duct system:

an HVAC system that consists of parallel ducts that produce a cold air stream in

one and a hot air stream in the other.

Dust:

an air suspension of particles (aerosol) of any solid material, usually with particle sizes <100 µm

in diameter.

Dust-spot test:

a procedure that uses atmospheric air or a defined dust to measure a filter’s ability to

remove particles. A photometer is used to measure air samples on either side of the filter, and the

difference is expressed as a percentage of particles removed.

Effective leakage area:

the area through which air can enter or leave the room. This does not include

supply, return, or exhaust ducts. The smaller the effective leakage area, the better isolated the room.

Endotoxin:

the lipopolysaccharides of gram-negative bacteria, the toxic character of which resides in

the lipid portion. Endotoxins generally produce pyrogenic reactions in persons exposed to these

204

bacterial components.

Enveloped virus:

a virus whose outer surface is derived from a membrane of the host cell (either

nuclear or the cell’s outer membrane) during the budding phase of the maturation process. This

membrane-derived material contains lipid, a component that makes these viruses sensitive to the action

of chemical germicides.

Evaporative condenser:

a wet-type, heat-rejection unit that produces large volumes of aerosols during

the process of removing heat from conditioned space air.

Exhaust air:

air removed from a space and not reused therein.

Exposure:

the condition of being subjected to something (e.g., infectious agents) that could have a

harmful effect.

Fastidious:

having complex nutritional requirements for growth, as in microorganisms.

Fill:

that portion of a cooling tower which makes up its primary heat transfer surface. Fill is

alternatively known as “packing.”

Finished water:

treated, or potable water.

Fixed room-air HEPA recirculation systems:

nonmobile devices or systems that remove airborne

contaminants by recirculating air through a HEPA filter. These may be built into the room and

permanently ducted or may be mounted to the wall or ceiling within the room. In either situation, they

are fixed in place and are not easily movable.

Fomite:

an inanimate object that may be contaminated with microorganisms and serves in their

transmission.

Free and available chlorine:

the term applied to the three forms of chlorine that may be found in

solution (i.e., chlorine [Cl

]

, hypochlorite [OCl

–

], and hypochlorous acid [HOCl]).

Germicide:

a chemical that destroys microorganisms. Germicides may be used to inactivate

microorganisms in or on living tissue (antiseptics) or on environmental surfaces (disinfectants).

Health-care–associated:

an outcome, usually an infection, that occurs in any health-care facility as a

result of medical care. The term “health-care–associated” replaces “nosocomial,” the latter term being

limited to adverse infectious outcomes occurring only in hospitals.

Hemodiafiltration:

a form of renal replacement therapy in which waste solutes in the patient’s blood

are removed by both diffusion and convection through a high-flux membrane.

Hemodialysis:

a treatment for renal replacement therapy in which waste solutes in the patient’s blood

are removed by diffusion and/or convection through the semipermeable membrane of an artificial

kidney or dialyzer.

Hemofiltration:

cleansing of waste products or other toxins from the blood by convection across a

semipermeable, high-flux membrane where fluid balance is maintained by infusion of sterile, pyrogen-

free substitution fluid pre- or post-hemodialyzer.

HEPA filter:

High Efficiency Particulate Air filters capable of removing 99.97% of particles 0.3 µm in

diameter and may assist in controlling the transmission of airborne disease agents. These filters may be

used in ventilation systems to remove particles from the air or in personal respirators to filter air before

it is inhaled by the person wearing the respirator. The use of HEPA filters in ventilation systems

requires expertise in installation and maintenance. To test this type of filter, 0.3 µm particles of

dioctylphthalate (DOP) are drawn through the filter. Efficiency is calculated by comparing the

downstream and upstream particle counts. The optimal HEPA filter allows only three particles to pass

through for every 10,000 particles that are fed to the filter.

Heterotrophic (heterotroph):

that which requires some nutrient components from exogenous sources.

Heterotrophic bacteria cannot synthesize all of their metabolites and therefore require certain nutrients

from other sources.

High-efficiency filter:

a filter with a particle-removal efficiency of 90%–95%.

High flux:

a type of dialyzer or hemodialysis treatment in which large molecules (>8,000 daltons [e.g.,

2 microglobulin]) are removed from blood.

High-level disinfection:

a disinfection process that inactivates vegetative bacteria, mycobacteria, fungi,

and viruses, but not necessarily high numbers of bacterial spores.

205

Housekeeping surfaces:

environmental surfaces (e.g., floors, walls, ceilings, and tabletops) that are not

involved in direct delivery of patient care in health-care facilities.

Hoyer lift:

an apparatus that facilitates the repositioning of the non-ambulatory patient from bed to

wheelchair or gurney and subsequently to therapy equipment (immersion tanks).

Hubbard tank:

a tank used in hydrotherapy that may accomodate whole-body immersion (e.g., as may

be indicated for burn therapy). Use of a Hubbard tank has been replaced largely by bedside post-lavage

therapy for wound care management.

HVAC:

Heating, Ventilation, Air Conditioning.

Iatrogenic:

induced in a patient by a physician’s activity, manner, or therapy. The term is used

especially in reference to an infectious complication or other adverse outcome of medical treatment.

Impactor:

an air-sampling device in which particles and microorganisms are directed onto a solid

surface and retained there for assay.

Impingement:

an air-sampling method during which particles and microorganisms are directed into a

liquid and retained there for assay.

Indirect transmission:

involves contact of a susceptible host with a contaminated intermediate object,

usually inanimate (a fomite).

Induction unit:

the terminal unit of an in-room ventilation system. Induction units take centrally

conditioned air and further moderate its temperature. Induction units are not appropriate for areas with

high exhaust requirements (e.g., research laboratories).

Intermediate-level disinfection:

a disinfection process that inactivates vegetative bacteria, most fungi,

mycobacteria, and most viruses (particularly the enveloped viruses), but does not inactivate bacterial

spores.

Isoform:

a possible configuration (tertiary structure) of a protein molecule. With respect to prion

proteins, the molecules with large amounts of

-conformation are the normal isoform of that particular

protein, whereas those prions with large amounts of

-sheet conformation are the proteins associated

with the development of spongiform encephalopathy (e.g., Creutzfeldt-Jakob disease [CJD]).

Laminar flow:

HEPA-filtered air that is blown into a room at a rate of 90 ± 10 feet/min in a

unidirectional pattern with 100 ACH–400 ACH.

Large enveloped virus:

viruses whose particle diameter is >50 nm and whose outer surface is covered

by a lipid-containing structure derived from the membranes of the host cells. Examples of large

enveloped viruses include influenza viruses, herpes simplex viruses, and poxviruses.

Laser plume:

the transfer of electromagnetic energy into tissues which results in a release of particles,

gases, and tissue debris.

Lipid-containing viruses:

viruses whose particle contains lipid components. The term is generally

synonymous with enveloped viruses whose outer surface is derived from host cell membranes. Lipid-

containing viruses are sensitive to the inactivating effects of liquid chemical germicides.

Lithotriptors:

instruments used for crushing caliculi (i.e., calcified stones, and sand) in the bladder or

kidneys.

Low efficiency filter:

the prefilter with a particle-removal efficiency of approximately 30% through

which incoming air first passes. See also Prefilter.

Low-level disinfection:

a disinfection process that will inactivate most vegetative bacteria, some fungi,

and some viruses, but cannot be relied upon to inactivate resistant microorganisms (e.g., mycobacteria

or bacterial spores).

Makeup air:

outdoor air supplied to the ventilation system to replace exhaust air.

Makeup water:

a cold water supply source for a cooling tower.

Manometer:

a device that measures the pressure of liquids and gases. A manometer is used to verify

air filter performance by measuring pressure differentials on either side of the filter.

Membrane filtration:

an assay method suitable for recovery and enumeration of microorganisms from

liquid samples. This method is used when sample volume is large and anticipated microbial

contamination levels are low.

Mesophilic:

that which favors a moderate temperature. For mesophilic bacteria, a temperature range of

206

68°F–131°F (20°C–55°C) is favorable for their growth and proliferation.

Mixing box:

the site where the cold and hot air streams mix in the HVAC system, usually situated

close to the air outlet for the room.

Mixing faucet:

a faucet that mixes hot and cold water to produce water at a desired temperature.

MMAD:

Mass Median Aerodynamic Diameter. This is the unit used by ACGIH to describe the size of

particles when particulate air sampling is conducted.

Moniliaceous:

hyaline or brightly colored. This is a laboratory term for the distinctive characteristics

of certain opportunistic fungi in culture (e.g.,

Aspergillus

spp. and

Fusarium

spp.).

Monochloramine:

the result of the reaction between chlorine and ammonia that contains only one

chlorine atom. Monochloramine is used by municipal water systems as a water treatment.

Natural ventilation:

the movement of outdoor air into a space through intentionally provided openings

(i.e., windows, doors, or nonpowered ventilators).

Negative pressure:

air pressure differential between two adjacent airspaces such that air flow is

directed into the room relative to the corridor ventilation (i.e., room air is prevented from flowing out of

the room and into adjacent areas).

Neutropenia:

a medical condition in which the patient’s concentration of neutrophils is substantially

less than that in the normal range. Severe neutropenia occurs when the concentration is <1,000

polymorphonuclear cells/µL for 2 weeks or <100 polymorphonuclear cells /mL for 1 week, particularly

for hematopoietic stem cell transplant (HSCT) recipients.

Noncritical devices:

medical devices or surfaces that come into contact with only intact skin. The risk

of infection from use of these devices is low.

Non-enveloped virus:

a virus whose particle is not covered by a structure derived from a membrane of

the host cell. Non-enveloped viruses have little or no lipid compounds in their biochemical

composition, a characteristic that is significant to their inherent resistance to the action of chemical

germicides.

Nosocomial:

an occurrence, usually an infection, that is acquired in a hospital as a result of medical

care.

NTM:

nontuberculous mycobacteria. These organisms are also known as atypical mycobacteria, or as

“Mycobacteria other than tuberculosis” (MOTT). This descriptive term refers to any of the fast- or

slow-growing

Mycobacterium

spp. found in primarily in natural or man-made waters, but it excludes

Mycobacterium tuberculosis

and its variants.

Nuisance dust:

generally innocuous dust, not recognized as the direct cause of serious pathological

conditions.

Oocysts:

a cyst in which sporozoites are formed; a reproductive aspect of the life cycle of a number of

parasitic agents (e.g.,

Cryptosporidium

spp., and

Cyclospora

spp.).

Outdoor air:

air taken from the external atmosphere and, therefore, not previously circulated through

the ventilation system.

Parallel streamlines:

a unidirectional airflow pattern achieved in a laminar flow setting, characterized

by little or no mixing of air.

Particulate matter (particles):

a state of matter in which solid or liquid substances exist in the form of

aggregated molecules or particles. Airborne particulate matter is typically in the size range of 0.01–100

µm diameter.

Pasteurization:

a disinfecting method for liquids during which the liquids are heated to 140°F (60

for a short time (>30 mins.) to significantly reduce the numbers of pathogenic or spoilage

microorganisms.

Plinth:

a treatment table or a piece of equipment used to reposition the patient for treatment.

Portable room-air HEPA recirculation units:

free-standing portable devices that remove airborne

contaminants by recirculating air through a HEPA filter.

Positive pressure:

air pressure differential between two adjacent air spaces such that air flow is

directed from the room relative to the corridor ventilation (i.e., air from corridors and adjacent areas is

prevented from entering the room).

207

Potable (drinking) water:

water that is fit to drink. The microbiological quality of this water as

defined by EPA microbiological standards from the Surface Water Treatment Rule: a)

Giardia lamblia

99.9% killed/inactivated; b) viruses: 99.9% inactivated; c)

Legionella

spp.: no limit, but if

Giardia

and

viruses are inactivated,

Legionella

will also be controlled; d) heterotrophic plate count [HPC]: <500

CFU/mL; and e) >5% of water samples total coliform-positive in a month.

PPE:

Personal Protective Equipment.

ppm:

parts per million. The term is a measure of concentration in solution. Chlorine bleaches

(undiluted) that are available in the U.S. (5.25%–6.15% sodium hypochlorite) contain approximately

50,000–61,500 parts per million of free and available chlorine.

Prefilter:

the first filter for incoming fresh air in a HVAC system. This filter is approximately 30%

efficient in removing particles from the air. See also Low-Efficiency Filter.

Prion:

a class of agent associated with the transmission of diseases knowns as transmissible

spongiform encephalopathies (TSEs). Prions are considered to consist of protein only, and the abnormal

isoform of this protein is thought to be the agent that causes diseases such as Creutzfeldt-Jakob disease

(CJD), kuru, scrapie, bovine spongiform encephalopathy (BSE), and the human version of BSE which is

variant CJD (vCJD).

Product water:

water produced by a water treatment system or individual component of that system.

Protective environment:

a special care area, usually in a hospital, designed to prevent transmission of

opportunistic airborne pathogens to severely immunosuppressed patients.

Pseudoepidemic (pseudo-outbreak):

a cluster of positive microbiologic cultures in the absence of

clinical disease. A pseudoepidemic usually results from contamination of the laboratory apparatus and

process used to recover microorganisms.

Pyrogenic:

an endotoxin burden such that a patient would receive >5 endotoxin units (EU) per

kilogram of body weight per hour, thereby causing a febrile response. In dialysis this usually refers to

water or dialysate having endotoxin concentrations of >5 EU/mL.

Rank order:

a strategy for assessing overall indoor air quality and filter performance by comparing

airborne particle counts from lowest to highest (i.e., from the best filtered air spaces to those with the

least filtration).

RAPD:

a method of genotyping microorganisms by randomly amplified polymorphic DNA. This is

one version of the polymerase chain reaction method.

Recirculated air:

air removed from the conditioned space and intended for reuse as supply air.

Relative humidity:

the ratio of the amount of water vapor in the atmosphere to the amount necessary

for saturation at the same temperature. Relative humidity is expressed in terms of percent and measures

the percentage of saturation. At 100% relative humidity, the air is saturated. The relative humidity

decreases when the temperature is increased without changing the amount of moisture in the air.

Reprocessing (of medical instruments):

the procedures or steps taken to make a medical instrument

safe for use on the next patient. Reprocessing encompasses both cleaning and the final or terminal step

(i.e., sterilization or disinfection) which is determined by the intended use of the instrument according to

the Spaulding classification.

Residuals:

the presence and concentration of a chemical in media (e.g., water) or on a surface after the

chemical has been added.

Reservoir:

a nonclinical source of infection.

Respirable particles:

those particles that penetrate into and are deposited in the nonciliated portion of

the lung. Particles >10 µm in diameter are not respirable.

Return air:

air removed from a space to be then recirculated.

Reverse osmosis (RO):

an advanced method of water or wastewater treatment that relies on a semi-

permeable membrane to separate waters from pollutants. An external force is used to reverse the

normal osmotic process resulting in the solvent moving from a solution of higher concentration to one

of lower concentration.

Riser:

water piping that connects the circulating water supply line, from the level of the base of the

tower or supply header, to the tower’s distribution system.

208

RODAC:

Replicate Organism Direct Agar Contact. This term refers to a nutrient agar plate whose

convex agar surface is directly pressed onto an environmental surface for the purpose of microbiologic

sampling of that surface.

Room-air HEPA recirculation systems and units:

devices (either fixed or portable) that remove

airborne contaminants by recirculating air through a HEPA filter.

Routine sampling:

environmental sampling conducted without a specific, intended purpose and with

no action plan dependent on the results obtained.

Sanitizer:

an agent that reduces microbial contamination to safe levels as judged by public health

standards or requirements.

Saprophytic:

a naturally-occurring microbial contaminant.

Sedimentation:

the act or process of depositing sediment from suspension in water. The term also

refers to the process whereby solids settle out of wastewater by gravity during treatment.

Semicritical devices:

medical devices that come into contact with mucous membranes or non-intact

skin.

Service animal:

any animal individually trained to do work or perform tasks for the benefit of a person

with a disability.

Shedding:

the generation and dispersion of particles and spores by sources within the patient area,

through activities such as patient movement and airflow over surfaces.

Single-pass ventilation:

ventilation in which 100% of the air supplied to an area is exhausted to the

outside.

Small, non-enveloped viruses:

viruses whose particle diameter is <50 nm and whose outer surface is

the protein of the particle itself and not that of host cell membrane components. Examples of small,

non-enveloped viruses are polioviruses and hepatitis A virus.

Spaulding Classification:

the categorization of inanimate medical device surfaces in the medical

environment as proposed in 1972 by Dr. Earle Spaulding. Surfaces are divided into three general

categories, based on the theoretical risk of infection if the surfaces are contaminated at time of use. The

categories are “critical,” “semicritical,” and “noncritical.”

Specific humidity:

the mass of water vapor per unit mass of moist air. It is expressed as grains of

water per pound of dry air, or pounds of water per pound of dry air. The specific humidity changes as

moisture is added or removed. However, temperature changes do not change the specific humidity

unless the air is cooled below the dew point.

Splatter:

visible drops of liquid or body fluid that are expelled forcibly into the air and settle out

quickly, as distinguished from particles of an aerosol which remain airborne indefinitely.

Steady state:

the usual state of an area.

Sterilization:

the use of a physical or chemical procedure to destroy all microbial life, including large

numbers of highly-resistant bacterial endospores.

Stop valve:

a valve that regulates the flow of fluid through a pipe. The term may also refer to a faucet.

Substitution fluid:

fluid that is used for fluid management of patients receiving hemodiafiltration.

This fluid can be prepared on-line at the machine through a series of ultrafilters or with the use of sterile

peritoneal dialysis fluid.

Supply air:

air that is delivered to the conditioned space and used for ventilation, heating, cooling,

humidification, or dehumidification.

Tensile strength:

the resistance of a material to a force tending to tear it apart, measured as the

maximum tension the material can withstand without tearing.

Therapy animal:

an animal (usually a personal pet) that, with their owners or handlers, provide

supervised, goal-directed intervention to clients in hospitals, nursing homes, special-population schools,

and other treatment sites.

Thermophilic:

capable of growing in environments warmer than body temperature.

Thermotolerant:

capable of withstanding high temperature conditions.

TLV®:

an exposure level under which most people can work consistently for 8 hours a day, day after

day, without adverse effects. The term is used by the ACGIH to designate degree of exposure to

209

contaminants. TLV® can be expressed as approximate milligrams of particulate per cubic meter of air

(mg/m

). TLVs® are listed as either an 8-hour TWA (time weighted average) or a 15-minute STEL

(short term exposure limit).

TLV-TWA:

Threshold Limit Value-Time Weighted Average. The term refers to the time-weighted

average concentration for a normal 8-hour workday and a 40-hour workweek to which nearly all

workers may be exposed repeatedly, day after day, without adverse effects. The TLV-TWA for

“particulates (insoluble) not otherwise classified” (PNOC) - (sometimes referred to as nuisance dust) -

are those particulates containing no asbestos and <1% crystalline silica. A TLV-TWA of 10 mg/m

for

inhalable particulates and a TLV-TWA of 3 mg/m

for respirable particulates (particulates <5 µm in

aerodynamic diameter) have been established.

Total suspended particulate matter:

the mass of particles suspended in a unit of volume of air when

collected by a high-volume air sampler.

Transient:

a change in the condition of the steady state that takes a very short time compared with the

steady state. Opening a door, and shaking bed linens are examples of transient activities.

TWA:

average exposure for an individual over a given working period, as determined by sampling at

given times during the period. TWA is usually presented as the average concentration over an 8-hour

workday for a 40-hour workweek.

Ultraclean air:

air in laminar flow ventilation that has also passed through a bank of HEPA filters.

Ultrafilter:

a membrane filter with a pore size in the range of 0.001–0.05 µm, the performance of

which is usually rated in terms of a nominal molecular weight cut-off (defined as the smallest molecular

weight species for which the filter membrance has more than 90% rejection).

Ultrafiltered dialysate:

the process by which dialysate is passed through a filter having a molecular

weight cut-off of approximately 1 kilodalton for the purpose of removing bacteria and endotoxin from

the bath.

Ultraviolet germicidal irradiation (UVGI):

the use of ultraviolet radiation to kill or inactivate

microorganisms.

Ultraviolet germicidal irradiation lamps:

lamps that kill or inactivate microorganisms by emitting

ultraviolet germicidal radiation, predominantly at a wavelength of 254 nm. UVGI lamps can be used in

ceiling or wall fixtures or within air ducts of ventilation systems.

Vapor pressure:

the pressure exerted by free molecules at the surface of a solid or liquid. Vapor

pressure is a function of temperature, increasing as the temperature rises.

Vegetative bacteria:

bacteria that are actively growing and metabolizing, as opposed to a bacterial

state of quiescence that is achieved when certain bacteria (gram-positive bacilli) convert to spores when

the environment can no longer support active growth.

Vehicle:

any object, person, surface, fomite, or media that may carry and transfer infectious

microorganisms from one site to another.

Ventilation:

the process of supplying and removing air by natural or mechanical means to and from

any space. Such air may or may not be conditioned.

Ventilation air:

that portion of the supply air consisting of outdoor air plus any recirculated air that has

been treated for the purpose of maintaining acceptable indoor air quality.

Ventilation, dilution:

an engineering control technique to dilute and remove airborne contaminants by

the flow of air into and out of an area. Air that contains droplet nuclei is removed and replaced by

contaminant-free air. If the flow is sufficient, droplet nuclei become dispersed, and their concentration

in the air is diminished.

Ventilation, local exhaust:

ventilation used to capture and removed airborne contaminants by

enclosing the contaminant source (the patient) or by placing an exhaust hood close to the contaminant

source.

v/v:

volume to volume. This term is an expression of concentration of a percentage solution when the

principle component is added as a liquid to the diluent.

w/v:

weight to volume. This term is an expression of concentration of a percentage solution when the

principle component is added as a solid to the diluent.

210

Weight-arrestance:

a measure of filter efficiency, used primarily when describing the performance of

low- and medium-efficiency filters. The measurement of weight-arrestance is performed by feeding a

standardized synthetic dust to the filter and weighing the fraction of the dust removed.

Appendix B. Air

1. Airborne Contaminant Removal

Table B.1. Air changes/hour (ACH) and time required for airborne-contaminant removal
efficiencies of 99% and 99.9%*

Time (mins.) required for removal:

ACH+ § ¶

99% efficiency 99.9%

efficiency

2 138 207

4 69 104

8 35 52

20 14 21

50 6 8

* This table is revised from Table S3-1 in reference 4 and has been adapted from the formula for the rate of purging airborne

contaminants presented in reference 1435.

+ Shaded entries denote frequently cited ACH for patient-care areas.

§ Values were derived from the formula:

– t

= – [ln (C

/ C

) / (Q / V)]

60, with t

= 0 and where

= initial timepoint in minutes

= final timepoint in minutes

= initial concentration of contaminant

= final concentration of contaminant

/ C

= 1 – (removal efficiency / 100)

Q = air flow rate in cubic feet/hour

V = room volume in cubic feet

Q / V = ACH

¶ Values apply to an empty room with no aerosol-generating source. With a person present and generating

aerosol, this table would not apply. Other equations are available that include a constant generating source.

However, certain diseases (e.g., infectious tuberculosis) are not likely to be aerosolized at a constant rate. The

times given assume perfect mixing of the air within the space (i.e., mixing factor = 1). However, perfect mixing

usually does not occur. Removal times will be longer in rooms or areas with imperfect mixing or air stagnation.

213

Caution should be exercised in using this table in such situations. For booths or other local ventilation enclosures,

manufacturers’ instructions should be consulted.

2. Air Sampling for Aerosols Containing Legionellae

Air sampling is an insensitive means of detecting

Legionella pneumophila,

and is of limited practical

value in environmental sampling for this pathogen. In certain instances, however, it can be used to a)

demonstrate the presence of legionellae in aerosol droplets associated with suspected bacterial

211

reservoirs; b) define the role of certain devices [e.g., showers, faucets, decorative fountains, or evaporate

condensers] in disease transmission; and c) quantitate and determine the size of the droplets containing

legionellae.

1436

Stringent controls and calibration are necessary when sampling is used to determine

particle size and numbers of viable bacteria.

1437

Samplers should be placed in locations where human

exposure to aerosols is anticipated, and investigators should wear a NIOSH-approved respirator (e.g.,

N95 respirator) if sampling involves exposure to potentially infectious aerosols.

Methods used to sample air for legionellae include impingement in liquid, impaction on solid medium,

and sedimentation using settle plates.

1436

The Chemical Corps.-type all-glass impingers (AGI) with the

stem 30 mm from the bottom of the flask have been used successfully to sample for legionellae.

1436

Because of the velocity at which air samples are collected, clumps tend to become fragmented, leading

to a more accurate count of bacteria present in the air. The disadvantages of this method are a) the

velocity of collection tends to destroy some vegetative cells; b) the method does not differentiate

particle sizes; and c) AGIs are easily broken in the field. Yeast extract broth (0.25%) is the

recommended liquid medium for AGI sampling of legionellae;

1437

standard methods for water samples

can be used to culture these samples.

Andersen samplers are viable particle samplers in which particles pass through jet orifices of decreasing

size in cascade fashion until they impact on an agar surface.

1218

The agar plates are then removed and

incubated. The stage distribution of the legionellae should indicate the extent to which the bacteria

would have penetrated the respiratory system. The advantages of this sampling method are a) the

equipment is more durable during use; b) the sampler can cetermine the number and size of droplets

containing legionellae; c) the agar plates can be placed directly in an incubator with no further

manipulations; and d) both selective and nonselective BCYE agar can be used. If the samples must be

shipped to a laboratory, they should be packed and shipped without refrigeration as soon as possible.

3. Calculation of Air Sampling Results

Assuming that each colony on the agar plate is the growth from a single bacteria-carrying particle, the

contamination of the air being sampled is determined from the number of colonies counted. The

airborne microorganisms may be reported in terms of the number per cubic foot of air sampled. The

following formulas can be applied to convert colony counts to organisms per cubic foot of air

sampled.

1218

For solid agar impactor samplers:

C / (R

P) = N

where N = number of organisms collected per cubic foot of air sampled

C = total plate count

R = airflow rate in cubic feet per minute

P = duration of sampling period in minutes

For liquid impingers:

V) / (Q

R) = N where C = total number of colonies from all aliquots plated

V = final volume in mL of collecting media

Q = total number of mL plated

P, R, and N are defined as above

212

4. Ventilation Specifications for Health-Care Facilities

The following tables from the AIA

Guidelines for Design and Construction of Hospitals and Health-Care Facilities, 2001

are reprinted with permission of the American Institute

of Architects and the publisher (The Facilities Guidelines Institute).

120

Table B.2. Ventilation requirements for areas affecting patient care in hospitals and outpatient facilities

Notes: This table is Table 7.2 in the AIA guidelines, 2001 edition. Superscripts used in this table refer to notes following the table.

Air movement

Minimum

AII air

relationship

air changes

total air

exhausted

Recirculated

Relative

Design

to adjacent

of outdoor

changes per

directly to

by means of

humidity

temperature

Area designation

area

air

per

hour

4, 5

outdoors

room

units

(%)

(degrees F [C])

Surgeru and critical care

Operating/surgical cystoscopic rooms

10, 11

Out

–

30–60 68–73

(20–23)

Delivery room

Out

–

30–60

68–73 (20–23)

Recovery room

–

30–60

70–75

(21–24)

Critical and intensive care

–

30–60

70–75 (21–24)

Newborn intensive care

–

30–60

72–78 (22–26)

Treatment room

– – 6

– – –

(24)

Trauma room

Out

–

30–60

70–75

(21–24)

Anesthesia

gas

storage

In – 8

Yes

– – –

Endoscopy In

–

30–60

68–73

(20–23)

Bronchoscopy

Yes

30–60

68–73

(20–23)

ER waiting rooms

Yes

14, 15

– –

70–75

(21–24)

Triage In

Yes

– –

70–75

(21–24)

Radiology waiting rooms

Yes

14, 15

– –

70–75

(21–24)

Procedure room

Out

–

30–60

70–75 (21–24)

Nursing

Patient room

–

– –

–

70–75

(21–24)

Toilet room

–

Yes

–

Newborn nursery suite

–

30–60

72–78 (22–26)

Protective environment room

11, 17

Out

2 12 – No – 75

(24)

Airborne infection isolation room

17, 18

12 Yes

No – 75

(24)

Isolation alcove or anteroom

17, 18

In/Out

– 10 Yes No – –

Labor/delivery/recovery –

– –

–

70–75

(21–24)

Labor/delivery/recovery/postpartum –

– –

–

70–75

(21–24)

Patient

corridor

– – 2

– – – –

213

Air movement

Minimum

AII air

relationship

air changes

total air

exhausted

Recirculated

Relative

Design

to adjacent

of outdoor

changes per

directly to

by means of

humidity

temperature

Area designation

area

air

per

hour

4, 5

outdoors

room

units

(%)

(degrees F [C])

Ancillary

Radiology

X-ray (surgical/critical care and

catheterization)

Out

–

30-60

70–75 (21–24)

X-ray (diagnostic & treatment)

–

75 (24)

Darkroom

–

Yes

–

Laboratory

General

– – 6

– – –

(24)

Biochemistry

Out

–

(24)

Cytology

–

Yes

–

(24)

Glass

washing

–

Yes

–

Histology

–

Yes

–

(24)

Microbiology

–

Yes

–

(24)

Nuclear medicine

–

Yes

–

75 (24)

Pathology

–

Yes

–

(24)

Serology

Out

–

(24)

Sterilizing

–

Yes

–

Autopsy room

–

Yes

–

Nonrefrigerated body-holding room

–

Yes

–

70 (21)

Pharmacy

Out – 4

– – – –

Diagnostic and treatment

Examination

room

– – 6

– – –

(24)

Medication

room

Out – 4

– – – –

Treatment

room

– – 6

– – –

(24)

Physical therapy and hydrotherapy

–

75 (24)

Soiled workroom or soiled holding

–

Yes

–

Clean workroom or clean holding

Out

–

Sterilizing and supply

ETO-sterilizer room

–

Yes

30-60

75 (24)

Sterilizer equipment room In

–

Yes

–

Central medical and surgical supply

Soiled or decontamination room

–

Yes

–

68–73 (20–23)

Clean workroom

Out

–

30-60

75 (24)

Sterile

storage

Out

–

(Max.)

–

214

Air movement

Minimum

AII air

relationship

air changes

total air

exhausted

Recirculated

Relative

Design

to adjacent

of outdoor

changes per

directly to

by means of

humidity

temperature

Area designation

area

air

per

hour

4, 5

outdoors

room

units

(%)

(degrees F [C])

Service

Food preparation center

–

Ware washing

–

Yes

–

Dietary day storage

–

Laundry,

general

–

– 10

Yes – – –

Soiled linen (sorting and storage)

–

Yes

–

Clean linen storage

Out

–

Soiled linen and trash chute room

–

Yes

–

Bedpan

room

– 10

Yes – – –

Bathroom

– 10 – – –

(24)

Janitor’s closet

–

Yes

–

Notes:

1. The ventilation rates in this table cover ventilation for comfort, as well as for asepsis and odor control in areas of acute care hospitals that directly affect patient care and are

determined based on health-care facilities being predominantly “No Smoking” facilities. Where smoking may be allowed, ventilation rates will need adjustment. Areas where

specific ventilation rates are not given in the table shall be ventilated in accordance with ASHRAE Standard 62,

Ventilation for Acceptable Indoor Air Quality

, and ASHRAE

Handbook - HVAC Applications

. Specialized patient care areas, including organ transplant units, burn units, specialty procedure rooms, etc., shall have additional ventilation

provisions for air quality control as may be appropriate. OSHA standards and/or NIOSH criteria require special ventilation requirements for employee health and safety within

health-care facilities.

2. Design of the ventilation system shall provide air movement which is generally from clean to less clean areas. If any form of variable air volume or load shedding system is

used for energy conservation, it must not compromise the corridor-to-room pressure balancing relationships or the minimum air changes required by the table.

3. To satisfy exhaust needs, replacement air from the outside is necessary. Table B2 does not attempt to describe specific amounts of outside air to be supplied to individual

spaces except for certain areas such as those listed. Distribution of the outside air, added to the system to balance required exhaust, shall be as required by good engineering

practice. Minimum outside air quantities shall remain constant while the system is in operation.

4. Number of air changes may be reduced when the room is unoccupied if provisions are made to ensure that the number of air changes indicated is reestablished any time the

space is being utilized. Adjustments shall include provisions so that the direction of air movement shall remain the same when the number of air changes is reduced. Areas not

indicated as having continuous directional control may have ventilation systems shut down when space is unoccupied and ventilation is not otherwise needed, if the maximum

infiltration or exfiltration permitted in Note 2 is not exceeded and if adjacent pressure balancing relationships are not compromised. Air quantity calculations must account for

filter loading such that the indicated air change rates are provided up until the time of filter change-out.

5. Air change requirements indicated are minimum values. Higher values should be used when required to maintain indicated room conditions (temperature and jumidity), based

on the cooling load of the space (lights, equipment, people, exterior walls and windows, etc.).

215

6. Air from areas with contamination and/or odor problems shall be exhausted to the outside and not recirculated to other areas. Note that individual circumstances may require

special consideration for air exhaust to the outside, (e.g., in intensive care units in which patients with pulmonary infection are treated) and rooms for burn patients.

7. Recirculating room HVAC units refer to those local units that are used primarily for heating and cooling of air, and not disinfection of air. Because of cleaning difficulty and

potential for buildup of contamination, recirculating room units shall not be used in areas marked “No.” However, for airborne infection control, air may be recirculated within

individual isolation rooms if HEPA filters are used. Isolation and intensive care unit rooms may be ventilated by reheat induction units in which only the primary air supplied from

a central system passes through the reheat unit. Gravity-type heating or cooling units such as radiators or convectors shall not be used in operating rooms and other special care

areas. See this table’s Appendix I for a description of recirculation units to be used in isolation rooms (A7).

8. The ranges listed are the minimum and maximum limits where control is specifically needed. The maximum and minimum limits are not intended to be independent of a

space’s associated temperature. The humidity is expected to be at the higher end of the range when the temperature is also at the higher end, and vice versa.

9. Where temperature ranges are indicated, the systems shall be capable of maintaining the rooms at any point within the range during normal operation. A single figure indicates

a heating or cooling capacity of at least the indicated temperature. This is usually applicable when patients may be undressed and require a warmer environment. Nothing in these

guidelines shall be construed as precluding the use of temperatures lower than those noted when the patients' comfort and medical conditions make lower temperatures desirable.

Unoccupied areas such as storage rooms shall have temperatures appropriate for the function intended.

10. National Institute for Occupational Safety and Health (NIOSH) criteria documents regarding “Occupational Exposure to Waste Anesthetic Gases and Vapors,” and “Control of

Occupational Exposure to Nitrous Oxide” indicate a need for both local exhaust (scavenging) systems and general ventilation of the areas in which the respective gases are utilized.

11. Differential pressure shall be a minimum of 0.01" water gauge (2.5 Pa). If alarms are installed, allowances shall be made to prevent nuisance alarms of monitoring devices.

12. Some surgeons may require room temperatures which are outside of the indicated range. All operating room design conditions shall be developed in consultation with

surgeons, anesthesiologists, and nursing staff.

13. The term “trauma room” as used here is the operating room space in the emergency department or other trauma reception area that is used for emergency surgery. The “first

aid room” and/or “emergency room” used for initial treatment of accident victims may be ventilated as noted for the “treatment room.” Treatment rooms used for bronchoscopy

shall be treated as Bronchoscopy rooms. Treatment rooms used for cryosurgery procedures with nitrous oxide shall contain provisions for exhausting waste gases.

14. In a ventilation system that recirculates air, HEPA filters can be used in lieu of exhausting the air from these spaces to the outside. In this application, the return air shall be

passed through the HEPA filters before it is introduced into any other spaces.

15. If it is not practical to exhaust the air from the airborne infection isolation room to the outside, the air may be returned through HEPA filters to the air-handling system
exclusively

serving the isolation room.

16. Total air changes per room for patient rooms, labor/delivery/recovery rooms, and labor/delivery/recovery/postpartum rooms may be reduced to 4 when supplemental heating

and/or cooling systems (radiant heating and cooling, baseboard heating, etc.) are used.

17. The protective environment airflow design specifications protect the patient from common environmental airborne infectious microbes (i.e.,

Aspergillus

spores). These special

ventilation areas shall be designed to provide directed airflow from the cleanest patient care area to less clean areas. These rooms shall be protected with HEPA filters at 99.97

percent efficiency for a 0.3 µm sized particle in the supply airstream. These interrupting filters protect patient rooms from maintenance-derived release of environmental microbes

from the ventilation system components. Recirculation HEPA filters can be used to increase the equivalent room air exchanges. Constant volume airflow is required for consistent

ventilation for the protected environment. If the facility determines that airborne infection isolation is necessary for protective environment patients, an anteroom should be

216

provided. Rooms with reversible airflow provisions for the purpose of switching between protective environment and airborne infection isolation functions are not acceptable.

18. The infectious disease isolation room described in these guidelines is to be used for isolating the airborne spread of infectious diseases, such as measles, varicella, or

tuberculosis. The design of airborne infection isolation (AII) rooms should include the provision for normal patient care during periods not requiring isolation precautions.

Supplemental recirculating devices may be used in the patient room to increase the equivalent room air exchanges; however, such recirculating devices do not provide the outside

air requirements. Air may be recirculated within individual isolation rooms if HEPA filters are used. Rooms with reversible airflow provisions for the purpose of switching

between protective environment and AII functions are not acceptable.

19. When required, appropriate hoods and exhaust devices for the removal of noxious gases or chemical vapors shall be provided (see Section 7.31.D14 and 7.31.D15 in the AIA

guideline [reference 120] and NFPA 99).

20. Food preparation centers shall have ventilation systems whose air supply mechanisms are interfaced appropriately with exhaust hood controls or relief vents so that exfiltration

or infiltration to or from exit corridors does not compromise the exit corridor restrictions of NFPA 90A, the pressure requirements of NFPA 96, or the maximum defined in the

table. The number of air changes may be reduced or varied to any extent required for odor control when the space is not in use. See Section 7.31.D1.p in the AIA guideline

(reference 120).

Appendix I:

A7. Recirculating devices with HEPA filters may have potential uses in existing facilities as interim, supplemental environmental controls to meet requirements for the control of

airborne infectious agents. Limitations in design must be recognized. The design of either portable or fixed systems should prevent stagnation and short circuiting of airflow. The

supply and exhaust locations should direct clean air to areas where health-care workers are likely to work, across the infectious source, and then to the exhaust, so that the health-

care worker is not in position between the infectious source and the exhaust location. The design of such systems should also allow for easy access for scheduled preventative

maintenance and cleaning.

A11. The verification of airflow direction can include a simple visual method such as smoke trail, ball-in-tube, or flutterstrip. These devices will require a minimum differential

air pressure to indicate airflow direction.

217

Table B.3. Pressure relationships and ventilation of certain areas of nursing facilities

Notes: This table is Table 8.1 in the AIA guidelines, 2001 edition. Superscripts used in this table refer to notes following the table.

Air movement

Minimum

AII air

relationship

air changes

total air

exhausted

Recirculated

Relative

Design

to adjacent

of outdoor

changes per

directly to

by means of

humidity

temperature

Area designation

area

air

per

hour

outdoors

room

units

(%)

(degrees F [C])

Resident room

–

70–75

(21–24)

Resident unit corridor

–

Resident gathering areas

–

Toilet room

–

Yes

–

Dining rooms

–

75 (24)

Activity rooms, if provided

–

Physical therapy

–

75 (24)

Occupational therapy

–

75.(24)

Soiled workroom or soiled holding

Yes

–

Clean workroom or clean holding

Out

–

(Max. 70)

75 (24)

Sterilizer exhaust room

–

Yes

–

Linen and trash chute room, if provided

–

Yes

–

Laundry, general, if provided

–

Yes

–

Soiled linen sorting and storage

–

Yes

–

Clean linen storage

Out

–

Yes

–

Food preparation facilities

– 2

Yes No

–

Dietary warewashing

–

Yes

–

Dietary storage areas

–

Yes

–

Housekeeping rooms

–

Yes

–

Bathing rooms

–

Yes

–

75 (24)

Notes:

1. The ventilation rates in this table cover ventilation for comfort, as well as for asepsis and odor control in areas of nursing facilities that directly affect resident care and are

determined based on nursing facilities being predominantly “No Smoking” facilities. Where smoking may be allowed, ventilation rates will need adjustment. Areas where

specific ventilation rates are not given in the table shall be ventilated in accordance with ASHRAE Standard 62,

Ventilation for Acceptable Indoor Air Quality,

and ASHRAE

Handbook - HVAC Applications.

OSHA standards and/or NIOSH criteria require special ventilation requirements for employee health and safety within nursing facilities.

2. Design of the ventilation system shall, insofar as possible, provide that air movement is from clean to less clean areas. However, continuous compliance may be impractical

with full utilization of some forms of variable air volume and load shedding systems that may be used for energy conservation. Areas that do require positive and continuous

control are noted with “Out” or “In” to indicate the required direction of air movement in relation to the space named. Rate of air movement may, of course, be varied as needed

218

within the limits required for positive control. Where indication of air movement direction is enclosed in parentheses, continuous directional control is required only when the

specialized equipment or device is in use or where room use may otherwise compromise the intent of movement from clean to less clean. Air movement for rooms with dashes

and nonpatient areas may vary as necessary to satisfy the requirements of those spaces. Additional adjustments may be needed when space is unused or unoccupied and air

systems are deenergized or reduced.

3. To satisfy exhaust needs, replacement air from outside is necessary. Table B.3 does not attempt to describe specific amounts of outside air to be supplied to individual spaces

except for certain areas such as those listed. Distribution of the outside air, added to the system to balance required exhaust, shall be as required by good engineering practice.

4. Number of air changes may be reduced when the room is unoccupied if provisions are made to ensure that the number of air changes indicated is reestablished any time the

space is being utilized. Adjustments shall include provisions so that the direction of air movement shall remain the same when the number of air changes is reduced. Areas not

indicated as having continuous directional control may have ventilation systems shut down when space is unoccupied and ventilation is not otherwise needed.

5. Air from areas with contamination and/or odor problems shall be exhausted to the outside and not recirculated to other areas. Note that individual circumstances may require

special consideration for air exhaust to outside.

6. Because of cleaning difficulty and potential for buildup of contamination, recirculating room units shall not be used in areas marked “No.” Isolation rooms may be ventilated

by reheat induction units in which only the primary air supplied from a central system passes through the reheat unit. Gravity-type heating or cooling units such as radiators or

convectors shall not be used in special care areas.

7. The ranges listed are the minimum and maximum limits where control is specifically needed. See A8.31.D in the AIA guideline (reference 120) for additional information.

8. Where temperature ranges are indicated, the systems shall be capable of maintaining the rooms at any point within the range. A single figure indicates a heating or cooling

capacity of at least the indicated temperature. This is usually applicable where residents may be undressed and require a warmer environment. Nothing in these guidelines shall be

construed as precluding the use of temperatures lower than those noted when the residents’ comfort and medical conditions make lower temperatures desirable. Unoccupied areas

such as storage rooms shall have temperatures appropriate for the function intended.

9. See A8.31.D1 in the AIA guideline (reference 120).

10. Food preparation facilities shall have ventilation systems whose air supply mechanisms are interfaced appropriately with exhaust hood controls or relief vents so that

exfiltration or infiltration to or from exit corridors does not compromise the exit corridor restrictions of NFPA 90A, the pressure requirements of NFPA 96, or the maximum

defined in the table. The number of air changes may be reduced or varied to any extent required for odor control when the space is not in use.

219

Table B.4. Filter efficiencies for central ventilation and air conditioning systems in
general hospitals*

Note: This table is Table 7.3 in the AIA guidelines, 2001 edition.

Filter bed

Number

No.1

No.

Area designation

filter beds

(%)

All areas for inpatient care, treatment, and

diagnosis, and those areas providing direct

service or clean supplies, such as sterile and

clean processing, etc.

Protective environment room

99.97

Laboratories 1

–

Administrative, bulk storage, soiled holding areas,

–

food preparation areas, and laundries

* Additional roughing or prefilters should be considered to reduce maintenance required for filters with efficiency higher

than 75 percent. The filtration efficiency ratings are based on average dust sopt efficiency per ASHRAE 52.1–1992.

Table B.5. Filter efficiencies for central ventilation and air conditioning systems in
outpatient facilities*

Note: This table is Table 9.1 in the AIA guidelines, 2001 edition.

Filter bed

Number of

No. 1

No. 2+

Area designation

filter beds

(%)

All areas for patient care, treatment, and/or

diagnosis, and those areas providing direct service

or clean supplies such as sterile and clean processing,

etc.

Laboratories 1

–

Administrative, bulk storage, soiled holding areas,

–

food preparation areas, and laundries

* Additional roughing or prefilters should be considered to reduce maintenance required for main filters. The filtration

efficiency ratings are based on dust spot efficiency per ASHRAE 52.1–1992.

+ These requirements do not apply to small primary (e.g., neighborhood) outpatient facilities or outpatient facilities that do

not perform invasive applications or procedures.

220

Table B.6. Filter efficiencies for central ventilation and air conditioning systems in
nursing facilities

Note: This table is Table 8.2 in the AIA guidelines, 2001 edition.

Minimum

Filter bed

number of

No. 1

No. 2

Area designation

filter beds

(%)*

All areas for inpatient care, treatment, and/or

diagnosis, and those areas providing direct

service or clean supplies

Administrative, bulk storage, soiled holding,

–

laundries, and food preparation areas

* The filtration efficiency ratings are based on average dust spot efficiency as per ASHRAE 52.1–1992.

Table B.7. Filter efficiencies for central ventilation and air conditioning systems in
psychiatric hospitals

Note: This table is Table 11.1 in the AIA guidelines, 2001 edition.

Minimum

Filter bed

number of

No. 1

No. 2

Area designation

filter beds

(%)*

All areas for inpatient care, treatment, and

diagnosis, and those areas providing direct

services

Administrative, bulk storage, soiled holding,

–

laundries, and food preparation areas

* The filtration efficiency ratings are based on average dust spot efficiency as per ASHRAE 52.1–1992.

Appendix C. Water

1. Biofilms

Microorganisms have a tendency to associate with and stick to surfaces. These adherent organisms can

initiate and develop biofilms, which are comprised of cells embedded in a matrix of extracellularly

produced polymers and associated abiotic particles.

1438

It is inevitable that biofilms will form in most

water systems. In the health-care facility environment, biofilms may be found in the potable water

supply piping, hot water tanks, air conditioning cooling towers, or in sinks, sink traps, aerators, or

shower heads. Biofilms, especially in water

systems, are not present as a continuous slime or

film, but

221

are more often scanty and heterogeneous in nature.

1439

Biofilms may form under stagnant as well as

flowing conditions, so storage tanks, in addition to water system piping, may be vulnerable to the

development of biofilm, especially if water temperatures are low enough to allow the growth of

thermophilic bacteria (e.g.,

Legionella

spp.). Favorable conditions for biofilm formation are present if

these structures and equipment are not cleaned for extended periods of time.

1440

Algae, protozoa, and fungi may be present in biofilms, but the predominant microorganisms of water

system biofilms are gram-negative bacteria. Although most of these organisms will not normally pose a

problem for healthy individuals, certain biofilm bacteria (e.g.,

Pseudomonas aeruginosa, Klebsiella

spp.,

Pantoea agglomerans

, and

Enterobacter cloacae

) all may be agents for opportunistic infections for

immunocompromised individuals.

1441, 1442

These biofilm organisms may easily contaminate indwelling

medical devices or intravenous (IV) fluids, and they could be transferred on the hands of health-care

workers.

1441–1444

Biofilms may potentially provide an environment for the survival of pathogenic

organisms, such as

Legionella pneumophila

and

E. coli

O157:H7. Although the association of biofilms

and medical devices provides a plausible explanation for a variety of health-care–associated infections,

it is not clear how the presence of biofilms in the water system may influence the rates of health-care–

associated waterborne infection.

Organisms within biofilms behave quite differently than their planktonic (i.e., free floating)

counterparts. Research has shown that biofilm-associated organisms are more resistant to antibiotics

and disinfectants than are planktonic organisms, either because the cells are protected by the polymer

matrix, or because they are physiologically different.

1445–1450

Nevertheless, municipal water utilities

attempt to maintain a chlorine residual in the distribution system to discourage microbiological growth.

Though chlorine in its various forms is a proven disinfectant, it has been shown to be less effective

against biofilm bacteria.

1448

Higher levels of chlorine for longer contact times are necessary to

eliminate biofilms.

Routine sampling of health-care facility water systems for biofilms is not warranted. If an

epidemiologic investigation points to the water supply system as a possible source of infection, then

water sampling for biofilm organisms should be considered so that prevention and control strategies can

be developed. An established biofilm is is difficult to remove totally in existing piping. Strategies to

remediate biofilms in a water system would include flushing the system piping, hot water tank, dead

legs, and those areas of the facility’s water system subject to low or intermittent flow. The benefits of

this treatment would include a) elimination of corrosion deposits and sludge from the bottom of hot

water tanks, b) removal of biofilms from shower heads and sink aerators, and c) circulation of fresh

water containing elevated chlorine residuals into the health-care facility water system.

The general strategy for evaluating water system biofilm depends on a comparision of the

bacteriological quality of the incoming municipal water and that of water sampled from within facility’s

distribution system. Heterotrophic plate counts and coliform counts, both of which are routinely run by

the municipal water utility, will at least provide in indication of the potential for biofilm formation.

Heterotrophic plate count levels in potable water should be <500 CFU/mL. These levels may increase

on occasion, but counts consistently >500 CFU/mL would indicate a general decrease in water quality.

A direct correlation between heterotrophic plate count and biofilm levels has been demonstrated.

1450

Therefore, an increase in heterotrophic plate count would suggest a greater rate and extent of biofilm

formation in a health-care facility water system. The water supplied to the facility should also contain

<1 coliform bacteria/100 mL. Coliform bacteria are organisms whose presence in the distribution

system could indicate fecal contamination. It has been shown that coliform bacteria can colonize

biofilms within drinking water systems. Intermittant contamination of a water system with these

organisms could lead to colonization of the system.

222

Water samples can be collected from throughout the health-care facility system, including both hot and

cold water sources; samples should be cultured by standard methods.

945

If heterotrophic plate counts in

samples from the facility water system are higher than those from samples collected at the point of

water entry to the building, it can be concluded that the facility water quality has diminished. If

biofilms are detected in the facility water system and determined by an epidemiologic and

environmental investigation to be a reservoir for health-care–associated pathogens, the municipal water

supplier could be contacted with a request to provide higher chlorine residuals in the distribution

system, or the health-care facility could consider installing a supplemental chlorination system.

Sample collection sites for biofilm in health-care facilities include a) hot water tanks; b) shower heads;

and c) faucet aerators, especially in immunocompromised patient-care areas. Swabs should be placed

into tubes containing phosphate buffered water, pH 7.2 or phosphate buffered saline, shipped to the

laboratory under refrigeration and processed within 24 hrs. of collection. Samples are suspended by

vortexing with sterile glass beads and plated onto a nonselective medium (e.g., Plate Count Agar or

R2A medium) and selective media (e.g., media for

Legionella

spp. isolation) after serial dilution. If the

plate counts are elevated above levels in the water (i.e. comparing the plate count per square centimeter

of swabbed surface to the plate count per milliliter of water), then biofilm formation can be suspected.

In the case of an outbreak, it would be advisable to isolate organisms from these plates to determine

whether the suspect organisms are present in the biofilm or water samples and compare them to the

organisms isolated from patient specimens.

2. Water and Dialysate Sampling Strategies in Dialysis

In order to detect the low, total viable heterotrophic plate counts outlined by the current AAMI

standards for water and dialysate in dialysis settings, it is necessary to use standard quantitative culture

techniques with appropriate sensitivity levels.

792, 832, 833

The membrane filter technique is particularly

suited for this application because it permits large volumes of water to be assayed.

792, 834

Since the

membrane filter technique may not be readily available in clinical laboratories, the spread plate assay

can be used as an alternative.

834

If the spread plate assay is used, however, the standard prohibits the

use of a calibrated loop when applying sample to the plate.

792

The prohibition is based on the low

sensitivity of the calibrated loop. A standard calibrated loop transfers 0.001 mL of sample to the culture

medium, so that the minimum sensitivity of the assay is 1,000 CFU/mL. This level of sensitivity is

unacceptable when the maximum allowable limit for microorganisms is 200 CFU/mL. Therefore, when

the spread plate method is used, a pipette must be used to place 0.1–0.5 mL of water on the culture

medium.

The current AAMI standard specifically prohibits the use of nutrient-rich media (e.g., blood agar, and

chocolate agar) in dialysis water and dialysate assays because these culture media are too rich for

growth of the naturally occurring organisms found in water.

792

Debate continues within AAMI,

however, as to the most appropriate culture medium and incubation conditions to be used. The original

clinical observations on which the microbiological requirements of this standard were based used

Standard Methods Agar (SMA), a medium containing relatively few nutrients.

666

The use of tryptic soy

agar (TSA), a general purpose medium for isolating and cultivating microorganisms was recommended

in later versions of the standard because it was thought to be more appropriate for culturing bicarbonate-

containing dialysate.

788, 789, 835

Moreover, culturing systems based on TSA are readily available from

commercial sources. Several studies, however, have shown that the use of nutrient-poor media, such as

R2A, results in an increased recovery of bacteria from water.

1451, 1452

The original standard also

specified incubation for 48 hours at 95°F–98.6°F (35°C–37°C) before enumeration of bacterial colonies.

Extending the culturing time up to 168 hours, or 7 days and using incubation temperatures of 73.4°F–

82.4°F (23°C–28°C) have also been shown to increase the recovery of

bacteria.

1451, 1452

Other

223

investigators, however, have not found such clear cut differences between culturing techniques.

835, 1453

After considerable discussion, the AAMI Committee has not reached a consensus regarding changes in

the assay technique, and the use of TSA or its equivalent for 48 hours at 95°F–98.6°F (35°C–37°C)

remains the recommended method. It should be recognized, however, that these culturing conditions

may underestimate the bacterial burden in the water and fail to identify the presence of some organisms.

Specifically, the recommended method may not detect the presence of various NTM that have been

associated with several outbreaks of infection in dialysis units.

31, 32

In these instances, however, the

high numbers of mycobacteria in the water were related to the total heterotrophic plate counts, each of

which was significantly greater than that allowable by the AAMI standard. Additionally, the

recommended method will not detect fungi and yeast, which have been shown to contaminate water

used for hemodialysis applications.

1454

Biofilm on the surface of the pipes may hide viable bacterial

colonies, even though no viable colonies are detected in the water using sensitive culturing

techniques.

1455

Many disinfection processes remove biofilm poorly, and a rapid increase in the level of

bacteria in the water following disinfection may indicate significant biofilm formation. Therefore,

although the results of microbiological surveillance obtained using the test methods outlined above may

be useful in guiding disinfection schedules and in demonstrating compliance with AAMI standards, they

should not be taken as an indication of the absolute microbiological purity of the water.

792

Endotoxin can be tested by one of two types of assays a) a kinetic test method [e.g., colorimetric or

turbidimetric] or b) a gel-clot assay. Endotoxin units are assayed by the

Limulus

Amebocyte Lysate

(LAL) method. Because endotoxins differ in their activity on a mass basis, their activity is referred to a

standard

Escherichia coli

endotoxin. The current standard (EC-6) is prepared from

E. coli

O113:H10.

The relationship between mass of endotoxin and its activity varies with both the lot of LAL and the lot

of control standard endotoxin used. Since standards for endotoxin were harmonized in 1983 with the

introduction of EC-5, the relationship between mass and activity of endotoxin has been approximately

5–10 EU/ng. Studies to harmonize standards have led to the measurement of endotoxin units (EU)

where 5 EU is equivalent to 1 ng

E. coli

O55:B5 endotoxin.

1456

In summary, water used to prepare dialysate and to reprocess hemodialyzers should not contain a total

microbial count >200 CFU/mL as determined by assay on TSA agar for 48 hrs. at 96.8°F (36°C), and

<2 endotoxin units (EU) per mL. The dialysate at the end of a dialysis treatment should not contain

>2,000 CFU/mL.

31, 32, 668, 789, 792

3. Water Sampling Strategies and Culture Techniques for Detecting
Legionellae

Legionella

spp. are ubiquitous and can be isolated from 20%–40% of freshwater environments,

including man-made water systems.

1457, 1458

In health-care facilities, where legionellae in potable water

rarely result in disease among immunocompromised patients, courses of remedial action are unclear.

Scheduled microbiologic monitoring for legionellae remains controversial because the presence of

legionellae is not necessarily evidence of a potential for causing disease.

1459

CDC recommends

aggressive disinfection measures for cleaning and maintaining devices known to transmit legionellae,

but does not recommend regularly scheduled microbiologic assays for the bacteria.

396

However,

scheduled monitoring of potable water within a hospital might be considered in certain settings where

persons are highly susceptible to illness and mortality from

Legionella

infection (e.g., hematopoietic

stem cell transplantation units and solid organ transplant units).

Also, after an outbreak of

224

legionellosis, health officials agree monitoring is necessary to identify the source and to evaluate the

efficacy of biocides or other prevention measures.

Examination of water samples is the most efficient microbiologic method for identifying sources of

legionellae and is an integral part of an epidemiologic investigation into health-care–associated

Legionnaires disease. Because of the diversity of plumbing and HVAC systems in health-care facilities,

the number and types of sites to be tested must be determined before collection of water samples. One

environmental sampling protocol that addresses sampling site selection in hospitals might serve as a

prototype for sampling in other institutions.

1209

Any water source that might be aerosolized should be

considered a potential source for transmission of legionellae. The bacteria are rarely found in municipal

water supplies and tend to colonize plumbing systems and point-of-use devices. To colonize,

legionellae usually require a temperature range of 77°F–108°F (25°C–42.2°C) and are most commonly

located in hot water systems.

1460

Legionellae do not survive drying. Therefore, air-conditioning

equipment condensate, which frequently evaporates, is not a likely source.

1461

Water samples and swabs from point-of-use devices or system surfaces should be collected when

sampling for legionellae (Box C.1).

1437

Swabs of system surfaces allow sampling of biofilms, which

frequently contain legionellae. When culturing faucet aerators and shower heads, swabs of surface areas

should be collected first; water samples are collected after aerators or shower heads are removed from

their pipes. Collection and culture techniques are outlined (Box C.2). Swabs can be streaked directly

onto buffered charcoal yeast extract agar (BCYE) plates if the pates are available at the collection site.

If the swabs and water samples must be transported back to a laboratory for processing, immersing

individual swabs in sample water minimizes drying during transit. Place swabs and water samples in

insulated coolers to protect specimens from temperature extremes.

Box C.1. Potential sampling sites for Legionella spp. in health-care facilities*

• Potable water systems

incoming water main, water softener unit, holding tanks, cisterns, water heater tanks

(at the inflows and outflows)

•

Potable water outlets, especially those in or near patient rooms

faucets or taps, showers

• Cooling towers and evaporative condensers

makeup water (e.g., added to replace water lost because of evaporation, drift, or leakage),

basin (i.e., area under the tower for collection of cooled water), sump (i.e., section of basin

from which cooled water returns to heat source), heat sources (e.g., chillers)

• Humidfiers (e.g., nebullizers)

bubblers for oxygen, water used for respiratory therapy equipment

• Other sources

decorative fountains, irrigation equipment, fire sprinkler system (if recently used), whirlpools,

spas

* Material in this box is adapted from reference 1209.

225

Box C.2. Procedures for collecting and processing environmental specimens for
Legionella spp.*

Collect water (1-liter samples, if possible) in sterile, screw-top bottles.

Collect culture swabs of internal surfaces of faucets, aerators, and shower heads in a sterile,

screw-top container (e.g., 50 mL plastic centrifuge tube). Submerge each swab in 5–10 mL of

sample water taken from the same device from which the sample was obtained.

Transport samples and process in a laboratory proficient at culturing water specimens for

Legionella

spp. as soon as possible after collection.+

Test samples for the presence of

Legionella

spp. by using semiselective culture media using

procedures specific to the cultivation and detection of

Legionella

spp.§¶

* Material in this table is compiled from references1209, 1437, 1462–1465.

+ Samples may be transported at room temperature but must be protected from temperature extremes. Samples not processed

within 24 hours of collection should be refrigerated.

§ Detection of

Legionella

spp. antigen by the direct fluorescent antibody technique is not suitable for environmental samples.

¶ Use of polymerase chain reaction for identification of

Legionella

spp. is not recommended until more data regading the

sensitivity and specificity of this procedure are available.

4. Procedure for Cleaning Cooling Towers and Related Equipment

I. Perform these steps prior to chemical disinfection and mechanical cleaning.

A. Provide protective equipment to workers who perform the disinfection, to prevent their exposure

to chemicals used for disinfection and aerosolized water containing

Legionella

spp. Protective

equipment may include full-length protective clothing, boots, gloves, goggles, and a full- or

half-face mask that combines a HEPA filter and chemical cartridges to protect against airborne

chlorine levels of up to 10 mg/L.

B. Shut off cooling tower.

1. Shut off the heat source, if possible.

2. Shut off fans, if present, on the cooling tower/evaporative condenser (CT/EC).

3. Shut off the system blowdown (i.e., purge) valve.

4. Shut off the automated blowdown controller, if present, and set the system controller to

manual.

5. Keep make-up water valves open.

6. Close building air-intake vents within at least 30 meters of the CT/EC until after the cleaning

procedure is complete.

7. Continue operating pumps for water circulation through the CT/EC.

II. Perform these chemical disinfection procedures.

A. Add fast-release, chlorine-containing disinfectant in pellet, granular, or liquid form, and follow

safety instructions on the product label. Use EPA-registered products, if available. Examples

of disinfectants include sodium hypochlorite (NaOCl) or calcium hypochlorite (Ca[OCl]

calculated to achieve initial free residual chlorine (FRC) of 50 mg/L: either a) 3.0 lbs [1.4 kg]

industrial grade NaOCl [12%–15% available Cl] per 1,000 gallons of CT/EC water; b) 10.5 lbs

[4.8 kg] domestic grade NaOCl [3%–5% available Cl] per 1,000 gallons of CT/EC water; or c)

226

0.6 lb [0.3 kg] Ca[OCl]

per 1,000 gallons of CT/EC water. If significant biodeposits are

present, additional chlorine may be required. If the volume of water in the CT/EC is unknown,

it can be estimated (in gallons) by multiplying either the recirculation rate in gallons per minute

by 10 or the refrigeration capacity in tons by 30. Other appropriate compounds may be

suggested by a water-treatment specialist.

B. Record the type and quality of all chemicals used for disinfection, the exact time the chemicals

were added to the system, and the time and results of FRC and pH measurements.

C. Add dispersant simultaneously with or within 15 minutes of adding disinfectant. The dispersant

is best added by first dissolving it in water and adding the solution to a turbulent zone in the

water system. Automatic-dishwasher compounds are examples of low- or nonfoaming, silicate-

based dispersants. Dispersants are added at 10–25 lbs (4.5–11.25 kg) per 1,000 gallons of

CT/EC water.

D. After adding disinfectant and dispersant, continue circulating the water through the system.

Monitor the FRC by using an FRC-measuring device with the DPD method (e.g., a swimming-

pool test kit), and measure the pH with a pH meter every 15 minutes for 2 hours. Add chlorine

as needed to maintain the FRC at >10 mg/L. Because the biocidal effect of chlorine is reduced

at a higher pH, adjust the pH to 7.5–8.0. The pH may be lowered by using any acid (e.g.,

nuriatic acid or sulfuric acid used for maintenance of swimming pools) that is compatible with

the treatment chemicals.

E. Two hours after adding disinfectant and dispersant or after the FRC level is stable at >10 mg/L,

monitor at 2-hour intervals and maintain the FRC at >10 mg/L for 24 hours.

F. After the FRC level has been maintained at >10 mg/L for 24 hours, drain the system. CT/EC

water may be drained safely into the sanitary sewer. Municipal water and sewerage authorities

should be contacted regarding local regulations. If a sanitary sewer is not available, consult

local or state authorities (e.g., a department of natural resources or environmental protection)

regarding disposal of water. If necessary, the drain-off may be dechlorinated by dissipation or

chemical neutralization with sodium bisulfite.

G. Refill the system with water and repeat the procedure outline in steps 2–7 in I-B above.

III. Perform mechanical cleaning.

A. After water from the second chemical disinfection has been drained, shut down the CT/EC.

B. Inspect all water-contact areas for sediment, sludge, and scale. Using brushes and/or a low-

pressure water hose, thoroughly clean all CT/EC water-contact areas, including the basin, sump,

fill, spray nozzles, and fittings. Replace components as needed.

C. If possible, clean CT/EC water-contact areas within the chillers.

IV. Perform these procedures after mechanical cleaning.

A. Fill the system with water and add chlorine to achieve an FRC level of 10 mg/L.

B. Circulate the water for 1 hour, then open the blowdown valve and flush the entire system until

the water is free of turbidity.

C. Drain the system.

D. Open any air-intake vents that were closed before cleaning.

E. Fill the system with water. The CT/EC may be put back into service using an effective water-

treatment program.

227

5. Maintenance Procedures Used to Decrease Survival and Multiplications
of Legionella spp. in Potable-Water Distribution Systems

Wherever allowable by state code, provide water at >124°F (>51°C) at all points in the heated water

system, including the taps. This requires that water in calorifiers (e.g., water heaters) be maintained at

>140°F (>60°C). In the United Kingdom, where maintenance of water temperatures at >122°F (>50°C)

in hospitals has been mandated, installation of blending or mixing valves at or near taps to reduce the

water temperature to <109.4°F (<63°C) has been recommended in certain settings to reduce the risk for

scald injury to patients, visitors, and health care workers.

726

However,

Legionella

spp. can multiply

even in short segments of pipe containing water at this temperature. Increasing the flow rate from the

hot-water-circulation system may help lessen the likelihood of water stagnation and cooling.

711, 1465

Insulation of plumbing to ensure delivery of cold (<68°F [<20°C]) water to water heaters (and to cold-

water outlets) may diminish the opportunity for bacterial multiplication.

456

Both dead legs and capped

spurs within the plumbing system provide areas of stagnation and cooling to <122°F (<50°C) regardless

of the circulating water temperature; these segments may need to be removed to prevent colonization.

704

Rubber fittings within plumbing systems have been associated with persistent colonization, and

replacement of these fittings may be required for

Legionella

spp. eradication.

1467

Continuous chlorination to maintain concentrations of free residual chlorine at 1–2 mg/L (1–2 ppm) at

the tap is an alternative option for treatment. This requires the placement of flow-adjusted, continuous

injectors of chlorine throughout the water distribution system. Adverse effects of continuous

chlorination can include accelerated corrosion of plumbing (resulting in system leaks) and production of

potentially carcinogenic trihalomethanes. However, when levels of free residual chlorine are below 3

mg/L (3 ppm), trihalomethane levels are kept below the maximum safety level recommended by the

EPA.

727, 1468, 1469

228

Appendix D. Insects and Microorganisms

Table D.1. Microorganisms isolated from arthropods in health-care settings

Insect Microorganism

category Microorganisms References

Gram-negative bacteria

Acinetobacter

spp

.; Citrobacter freundii;

Enterobacter

spp

., E. cloacae; Escherichia

coli; Flavobacterium

spp

.; Klebsiella

spp

Proteus

spp

.; Pseudomonas

spp

., P.

aeruginosa, P. fluorescens, P. putida;
Salmonella

spp

.; Serratia

spp

., S.

marcescens; Shigella boydii

1048, 1051, 1056,

1058, 1059, 1062

Gram-positive bacteria

Bacillus

spp

.; Enterococcus faecalis;

Micrococcus

spp

.; Staphylococcus aureus,

S. epidermidis; Streptococcus

spp

., S.

viridans

1056, 1058, 1059

Acid-fast bacteria

Mycobacterium tuberculosis

1065

Fungi

Aspergillus niger

;

Mucor

spp.;

Rhizopus

spp.

1052, 1059

Cockroaches

Parasites

Endolimax nana; Entamoeba coli

1059

Gram-negative bacteria

Acinetobacter

spp

.; Campulobacter fetus

subsp

. Jejuni; Chlamydia

spp.

; Citrobacter

fruendii; Enterobacter

spp

.; Escherichia

coli; Helicobacter pylori; Klebsiella

spp

Proteus

spp.

; Pseudomonas aeruginosa;

Serratia marcescens; Shigella

spp

1047, 1048, 1050,

1053–1055, 1060

Gram-positive bacteria

Bacillus

spp

.; Enterococcus faecalis;

Micrococcus

spp

.; Staphylococcus

spp.

(coagulase-negative)

, S. aureus;

Streptococcus

spp

., S. viridans

1048, 1060

Fungi / yeasts

Candida

spp

.; Geotrichum

spp

1060

Parasites

Endolimax nana; Entamoeba coli

1060

Houseflies

Viruses Rotaviruses

1049

Gram-negative bacteria

Acinetobacter

spp

.; Escherichia coli;

Klebsiella

spp

.; Neisseria sicca; Proteus

spp

.; Providencia

spp

.; Pseudomonas

aeruginosa, P. fluorescens

1057

Ants

Gram-positive bacteria

Bacillus

spp

., B. cereus, B. pumilis;

Clostridium cochlearium, C. welchii;
Enterococcus faecalis; Staphylococcus

spp.

(coagulase-negative)

, S. aureus;

Streptococcus pyrogenes

1057

Gram-negative bacteria

Acinetobacter

spp

.; Citrobacter freundii;

Enterobacteraerogenes; Morganella
morganii

1048

Spiders

Gram-positive bacteria

Staphylococcus

spp. (coagulase-negative)

1048

Bram-negative bacteria

Acinetobacter

spp.

; Burkholderia cepacia;

Enterbacter agglomerans, E. aerogenes;
Hafnia alvei; Pseudomonas aeruginosa

1048

Mites, midges

Gram-positive bacteria

Staphylococcus

spp. (coagulase-negative)

1048

Gram-negative bacteria

Acinetobacter calcoaceticus; Enteobacter
cloacae

1048

Mosquitoes

Gram-positive bacteria

Enterococcus

spp

.; Staphylococcus

spp.

(coagulase-negative)

1048

229

Appendix E. Information Resources

The following sources of information may be helpful to the reader. Some of these are available at no

charge, while others are available for purchase from the publisher.

Air andWater

•

Jensen PA, Schafer MP. Sampling and characterization of bioaerosols. NIOSH Manual of

Analytical Methods; revised 6/99. www.cdc.gov/niosh/nmam/pdfs/chapter-j.pdf

•

American Institutes of Architects.

Guidelines for Design and Construction of Hospital and

Health Care Facilities.

Washington DC; American Institute of Architects Press; 2001. AIA,

1735 New York Avenue, NW, Washington DC 20006. 1-800-AIA-3837 or (202) 626-7541

•

ASHRAE. Standard 62, and Standard 12-2000. These documents may be purchased from:

American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. 1791 Tullie

Circle, NE, Atlanta GA 30329 1-800-527-4723 or (404) 636-8400.

•

University of Minnesota websites: www.dehs.umn.edu Indoor air quality site:

www.dehs.umn.edu/resources.htm#indoor Water infiltration and use of the wet test

(moisture) meter: www.dehs.umn.edu/remangi.html

•

The CDC website for bioterrorism information contains the interim intervention plan for

smallpox. The plan discusses infection control issues both for home-based care and hospital-

based patient management. www.bt.cdc.gov/agent/smallpox/response-plan/index.asp

Environmental Sampling

•

ISO. Sterilization of medical devices – microbiological methods, Part 1. ISO standard 11737-

1. Paramus NJ; International Organization for Standardization; 1995.

Animals in Health-Care Facilities

•

Service animal information with respect to the Americans with Disabilities Act. Contact the

U.S. Department of Justice ADA Information Line at (800) 514-0301 (voice) or (800) 514-0383

(TDD), or visit the ADA website at: www.usdoj.gov/crt/ada/adahom1.htm

Regulated Medical Waste

•

U.S. Environmental Protection Agency. This is the Internet address on their Internet web site

that will link to any state for information about medical waste rules and regulations at the state

level: www.epa.gov/epaoswer/other/medical/stregs.htm

General Resources

•

APIC Text of Infection Control and Epidemiology. Association for Professionals in Infection

Control and Epidemiology, Inc. Washington DC; 2000. (Two binder volumes, or CD-ROM)

•

Abrutyn E, Goldmann DA, Scheckler WE. Saunders Infection Control Reference Service, 2

Edition. Philadelphia PA; WB Saunders; 2000.

•

ECRI publications are available on a variety of healthcare topics. Contact ECRI at (610) 825-

6000. CRI, 5200 Butler Pike, Plymouth Meeting, PA 19462-1298.

230

Appendix F. Areas of Future Research

Air

• Standardize the methodology and interpretation of microbiologic air sampling (e.g., determine action

levels or minimum infectious dose for aspergillosis, and evaluate the significance of airborne

bacteria and fungi in the surgical field and the impact on postoperative SSI).

• Develop new molecular typing methods to better define the epidemiology of health-care–associated

outbreaks of aspergillosis and to associate isolates recovered from both clinical and environmental

sources.

• Develop new methods for the diagnosis of aspergillosis that can lead reliably to early recognition of

infection.

• Assess the value of laminar flow technology for surgeries other than for joint replacement surgery.

• Determine if particulate sampling can be routinely performed in lieu of microbiologic sampling for

purposes such as determining air quality of clean environments (e.g., operating rooms, HSCT units).

Water

• Evaluate new methods of water treatment, both in the facility and at the water utility (e.g., ozone,

chlorine dioxide, copper/silver/monochloramine) and perform cost-benefit analyses of treatment in

preventing health-care–associated legionellosis.

• Evaluate the role of biofilms in overall water quality and determine the impact of water treatments

for the control of biofilm in distribution systems.

• Determine if the use of ultrapure fluids in dialysis is feasible and warranted, and determine the action

level for the final bath.

• Develop quality assurance protocols and validated methods for sampling filtered rinse water used

with AERs and determine acceptable microbiologic quality of AER rinse water.

Environmental Services

• Evaluate the innate resistance of microorganisms to the action of chemical germicides, and

determine what, if any, linkage there may be between antibiotic resistance and resistance to

disinfectants.

Laundry and Bedding

• Evaluate the microbial inactivation capabilities of new laundry detergents, bleach substitutes, other

laundry additives, and new laundry technologies.

Animals in Health-Care Facilities

• Conduct surveillance to monitor incidence of infections among patients in facilities that use animal

programs, and conduct investigations to determine new infection control strategies to prevent these

infections.

• Evaluate the epidemiologic impact of performing procedures on animals (e.g., surgery or imaging) in

human health-care facilities.

Regulated Medical Waste

• Determine the efficiency of current medical waste treatment technologies to inactivate emerging

pathogens that may be present in medical waste (e.g., SARS-coV).

• Explore options to enable health-care facilities to reinstate the capacity to inactivate microbiological

cultures and stocks on-site.

231

Index—Parts I and IV

AAMI standards ..................................59, 60, 62, 222, 223

Acinetobacter

spp. ...........................11, 20, 43, 44, 99, 104

aerators ................................47, 48, 94, 220–222, 224, 225

aerosols... 12, 27, 41, 47, 56, 59, 67, 75, 76, 78, 80, 85, 89,

90, 98, 106, 111, 113, 114

AIA guidelines.............................17, 18, 19, 25, 37, 39, 99

AII rooms ................................................................. 35–37

air changes per hour (ACH).......6, 12, 16, 18, 31, 111, 210

air conditioners ........................................................... 8, 22

air conditioning systems ............................... 13, 20, 57, 59

air filtration................................................................... 111

air intakes ............................................................... 31, 226

air sampling ...............................26, 29, 89, 90, 91, 93, 210

airborne infection isolation (AII)................................ 6, 19

airborne transmission...................................................... 12

air-fluidized beds .......................................................... 104

alcohol-based hand rubs ................................................. 53

alkaline glutaraldehyde................................................... 70

allergens............................................................ 17, 80, 107

American Institute of Architects (AIA) .......................... 13

Americans with Disabilities Act........................... 108, 110

amplified stocks and cultures................................ 114, 115

Animal Assisted Activities ................................... 106, 107

Animal Assisted Therapy ..................................... 106, 107

animal bites................................................................... 107

animal handler .............................................................. 107

animal patient ............................................................... 110

Animal Welfare Act...................................................... 112

anterooms ................................................12, 25, 33, 36–38

ants ................................................................................. 81

ASHRAE............................................................ 13, 47, 49

aspergillosis...............................7, 8, 16, 19, 21, 35, 79, 80

Aspergillus fumigatus

............................................. 7, 8, 29

Aspergillus

spp. .........................5, 7, 20, 21, 28, 32, 34, 81

automated cyclers ........................................................... 65

automated endoscope reprocessor....................... 50, 69, 70

autopsy suites/rooms................................................. 12, 87

bacterial spores ................................................... 73, 84, 89

bank of filters.................................................................. 14

barrier ............................................................................. 34

barrier precautions/protection......................... 74, 109, 116

barriers................................................................ 27, 31, 33

bassinets.......................................................................... 76

biofilms..................................46, 54, 64, 71, 220–222, 224

biosafety level............................................................... 114

bioterrorism ............................................................ 89, 114

bird droppings....................................................... 9, 20, 22

birthing tanks............................................................ 67, 69

blood.. 12, 64, 69, 75, 77–79, 86, 87, 98, 99, 102, 113, 116

bloodborne pathogens............................................. 73, 116

boil water advisory ................................................... 51, 52

calibrated loop .............................................................. 222

carpet cleaning................................................................ 79

carpet tiles....................................................................... 79

carpeting ..................................................22, 25, 52, 78, 79

cats.........................................................105, 106, 108, 109

chain of infection........................................................ 4, 87

chemical germicides ................................73, 74, 77, 80, 84

chloramine/chloramine-T ............................................... 68

chlorine....................................46, 50, 53, 69, 84, 221, 226

chlorine bleach........................................................ 78, 101

chlorine residual ............................50, 68, 69, 94, 101, 221

cleaning .. 68, 70–72, 74, 78, 80, 83, 85, 86, 107, 109, 112,

225

cleaning cloths................................................................ 75

cleaning solutions ..................................................... 75, 76

Clostridium difficile

.................................................... 5, 84

cloth chairs...................................................................... 79

cockroaches .................................................................... 81

coliform bacteria........................................................... 221

colonization .......................42–44, 68, 70, 83, 99, 106, 227

colony counts................................................................ 211

commissioning.......................................................... 29, 89

construction ..... 7, 13, 14, 21, 23, 26, 27, 29, 31, 37, 76, 89

construction workers........................................... 24, 26, 31

contact precautions ......................................................... 85

contact time ................................................ 74, 84, 88, 221

contaminants..........................................14, 18, 19, 59, 210

contaminated fabrics....................................... 98, 101, 102

contingency plans ..................................................... 21, 50

continuous chlorination ................................................ 227

cooling tower...........................41, 53, 55, 57–59, 220, 225

copper/silver ions............................................................ 54

copper-8-quinolinolate.................................................... 35

Creutzfeldt-Jakob disease ....................................... 86, 116

Cryptosporidium parvum

................................................ 46

dead legs........................................................... 59, 64, 221

decorative fountains.......................................... 47, 49, 224

demolition..................................................... 23, 25, 26, 29

dental unit water lines..................................................... 71

detergent/disinfectant................................................ 74–76

dialysate.................................................................... 59–62

dialysis machines............................................................ 64

dialysis water................................................................ 222

dialyzer ........................................................................... 62

dialyzer membranes........................................................ 61

232

dialyzer reprocessing ...................................................... 59

dioctylphthalate (DOP) particle test................................ 15

direct contact........................6, 41, 67, 85, 86, 98, 108, 111

direct threat................................................................... 109

disinfectant fogging ........................................................ 75

disinfectant residuals ...................................................... 96

disinfectants...................................................... 21, 76, 225

disinfecting ........................71, 74, 80, 83, 85, 86, 112, 226

disinfection ................................................... 63, 64, 68, 70

dispersant...................................................................... 226

disposal (of medical waste)........................................... 113

distribution system.................................................. 94, 221

dogs ...................................................... 105, 106, 108, 109

drift eliminators .............................................................. 58

drinking water................................................................. 71

droplet nuclei .............................................. 6, 7, 10, 12, 89

droplets ..................................................... 6, 55, 85, 86, 89

dry cleaning .................................................................. 102

drying.............................................................................. 11

dual-duct system ............................................................. 20

duct cleaning................................................................... 21

ductwork................................................................... 20, 22

dust ....................................8, 20, 24, 27, 30, 32, 74, 79, 93

dust-spot test................................................................... 15

education......................................................................... 24

electrical generators........................................................ 53

emergency....................................................................... 53

endotoxin .................................................... 60–62, 64, 223

engineering controls........................................................ 36

enteric viruses................................................................. 85

environmental cultures.............................................. 83, 88

Environmental Protection Agency (EPA).... 21, 73–75, 77,

103, 227

environmental sampling............................................ 88, 95

environmental surfaces ...11, 44, 71, 72, 74, 82–86, 88, 98,

107

environmental surveillance ....................................... 54, 55

EPA registration.................................................. 73, 76, 83

EPA-registered germicides ........................... 75, 78, 85, 86

evaporative condensers....................................... 41, 57–59

exclusion (of a service animal) ..................................... 109

exotic animals............................................................... 110

fan-coil units................................................................... 18

faucets..........................................47, 54, 94, 222, 224, 225

fecal contamination......................................................... 84

FIFRA..................................................................... 75, 103

filter efficiency ......................................................... 27, 29

filtration .......................................................................... 15

fire codes ........................................................................ 31

fish........................................................................ 105, 108

fish tanks....................................................................... 108

flies ................................................................................. 81

flooding........................................................................... 51

floors............................................................. 25, 75, 82, 83

flowers ............................................................................ 80

flush times....................................................................... 51

flutter strips......................................................... 20, 34, 36

fomites ................................................................ 3, 4, 7, 85

Food and Drug Administration (FDA).............. 69, 73, 103

free residual chlorine ................................ 51, 54, 225–227

fungal spores...8, 15, 16, 19–21, 26–28, 31, 34, 38, 79, 89,

fungi..................................................................................8

furniture .............................................................. 52, 79, 82

gram-negative bacteria...11, 41, 42, 48, 50, 60, 63, 64, 221

gram-positive bacteria............................................... 11, 84

hand hygiene............................................. 25, 71, 107, 109

hand transferral ..........................3, 44, 65, 82–84, 106, 221

handwashing ......................................... 25, 80, 84, 99, 107

hantaviruses .................................................................... 12

hematopoietic stem cell transplant....................................6

hemodiafiltration............................................................. 62

hemodialysis ......................................... 59, 60, 62, 64, 223

hemodialysis patients........................................................7

hemofiltration ................................................................. 62

HEPA filtration/filters........6, 12, 14, 15, 17, 31, 32, 36, 76

hepatitis B virus .................................................. 40, 73, 98

heterotrophic plate counts............. 51, 62, 66, 95, 221–223

high-flux membranes ...................................................... 61

high-level disinfectants................................................... 73

high-level disinfection ........................................ 60, 69, 72

high-temperature flushing............................................... 50

high-touch surfaces............................................. 75, 83–85

holding tank .................................................................... 47

hospital disinfectant ........................................................ 73

hot water system ....................................................... 51, 54

hot water tanks................................................ 53, 220–222

hot water temperature ..................................................... 49

housekeeping surfaces ........................ 3, 64, 72, 74–77, 83

HSCT patients............................................................. 6, 37

HSCT units ........................................... 11, 26, 79, 80, 107

Hubbard tanks................................................................. 68

human health-care facilities .................................. 110, 111

human immunodeficiency virus...................................... 73

humidifiers.......................................................... 17, 23, 41

humidity............................................ 13, 14, 17, 20, 38, 90

HVAC systems ................13, 14, 16, 17, 19–21, 27, 30, 51

hydrotherapy equipment ........................................... 67–69

hydrotherapy pools ......................................................... 68

hydrotherapy tanks.............................................. 67, 68, 82

hygienically-clean laundry.............................. 98–100, 102

hyperchlorination.......................................... 50, 53, 54, 59

233

I, J

iatrogenic cases............................................................... 87

ice machines and ice..................................... 25, 48, 65, 66

ice-storage chests............................................................ 66

immunocompromised patients....6, 7, 9, 26, 29–31, 34, 42,

47, 56, 66, 80, 107, 108, 223

impaction................................................................ 90, 211

impactors .................................................................. 28, 93

impingement..................................................... 90, 93, 211

impingers...................................................................... 211

inactivation studies ......................................................... 87

incineration........................................................... 113, 114

incubators (nursery)........................................................ 76

indirect transmission......................................................... 6

indirect contact ............................................................... 41

indoor air .................................................21, 24, 26, 27, 90

industrial-grade HEPA filter......................... 16, 31, 38, 39

infection-control risk assessment (ICRA).... 26, 29, 31, 35,

108, 111

influenza viruses............................................. 6, 12, 73, 85

innate resistance.................................................. 72, 73, 84

insects....................................................................... 67, 81

insulation material .......................................................... 20

intermediate-level disinfectants ...............73, 78, 83, 85, 86

intermediate-level disinfection ....................................... 72

isolation/isolation areas .................................... 11, 36, 100

JCAHO ......................................................... 13, 14, 51, 59

laboratories . 12, 13, 32, 47, 78, 79, 83, 105, 111, 112, 114,

222

laboratory confirmation .................................................. 55

laminar airflow ................................................... 18, 34, 38

laser plumes.................................................................... 40

laundry............................................................................ 49

laundry bags ................................................................. 100

laundry chutes............................................................... 100

laundry cycles............................................................... 101

laundry disinfection ...................................................... 101

laundry facility................................................................ 99

laundry packaging................................................. 100, 101

laundry process................................................. 98, 99, 102

laundry services.............................................................. 99

laundry transport................................................... 100, 101

Legionella pneumophila

....................................... 210, 221

Legionella

spp. ... 41, 42, 50, 54–57, 59, 71, 222, 223, 225,

227

legionellae .................................................41, 54, 211, 223

legionellosis...................................................... 53–56, 224

Legionnaires disease..............................41, 47, 57, 58, 224

liquid chemical sterilant.................................................. 70

low-level disinfectants.................................. 72, 73, 83, 86

low-level disinfection ............................................... 60, 64

manufacturer’s instructions...........67, 69, 74, 86, 102, 116

material safety data sheets (MSDS).......................... 75, 87

mattress cover......................................................... 77, 104

mattresses ............................................................... 77, 104

medical equipment.................................................... 74, 83

medical equipment surfaces............................................ 72

medical gas piping.......................................................... 30

medical records............................................................... 51

medical waste ............................................... 112, 113, 117

medical waste management .......................................... 112

membrane filtration .................................... 70, 95, 96, 222

methicillin-resistant

Staphylococcus aureus

(MRSA) ... 82,

83, 104, 105

microbial inactivation ..................................................... 72

microbial resistance ........................................................ 70

microbiologic air sampling ............................................. 27

microbiologic cultures and stocks................................. 112

microbiologic sampling .................................................. 64

microbiologic sampling of laundry............................... 102

microbiological wastes ......................................... 112, 114

moisture.............................................20, 24, 32, 51, 70, 96

moisture meters............................................................... 51

molecular typing............................................................. 28

monochloramine ............................................................. 54

mop heads....................................................................... 75

multidisciplinary team .............................................. 23, 91

municipal water ................................................ 47, 50, 224

municipal water systems/utilities............................ 45, 221

Mycobacterium tuberculosis

..................... 5, 7, 10, 73, 114

myiasis............................................................................ 81

negative air pressure .....6, 12, 18, 19, 21, 36, 99, 100, 104,

111

neutralizer chemicals ...................................................... 96

NIOSH............................................................................ 40

nontuberculous mycobacteria (NTM).5, 41, 44–46, 60, 63,

70, 71, 223

operating rooms .....13, 15, 17, 34, 38, 76, 82, 87, 109, 111

opportunistic infections ................................................ 4, 5

organic matter................................................................. 78

OSHA ......................................13, 73, 77, 79, 98, 100, 113

outdoor air ...............................................14, 15, 18, 25, 91

oxygen-based laundry detergents.................................. 101

particle sampling................................................. 27, 33, 89

performance measures ...................................................... 2

periodic culturing............................................................ 57

peritoneal dialysis..................................................... 64, 65

234

personal protective equipment .....77, 98, 99, 112, 114, 225

persons with disabilities........................................ 108, 109

person-to-person transmission .................................. 12, 85

pest control ..................................................................... 82

phenolics......................................................................... 76

pillows .......................................................................... 104

pipes.................................................. 64, 69, 221, 223, 224

planktonic organisms .................................................... 221

plastic enclosures............................................................ 31

plastic wrapping.............................................................. 74

Pneumocystis carinii

......................................................... 9

pneumonia ................................................................ 42, 55

point-of-use fixtures.......................................... 47, 51, 224

polyvinylchloride (PVC)........................................... 46, 64

pools ............................................................................... 67

positive air pressure .................................................. 18, 38

potable water................................................................. 220

potted plants................................................................ 8, 80

pressure differentials............................... 18, 19, 25, 30, 38

primates ........................................................ 105, 106, 111

prions ...................................................................... 86, 116

privacy curtains............................................................... 75

product water ............................................................ 64, 70

protective environment (PE)............. 6, 18, 19, 34, 56, 108

Pseudomonas aeruginosa

.5, 11, 20, 42, 68, 70, 71, 73, 79,

80, 96, 104, 221

pseudo-outbreaks ...................................................... 44, 70

pyrogenic reactions................................................... 60, 61

quality assurance................................................. 89, 94, 95

R2A media.................................................................... 222

rank order........................................................................ 27

recirculation.............................................................. 16, 18

recirculation loops .......................................................... 46

recreational equipment.................................................... 69

reduced nutrient media.................................................... 94

reducing agent................................................................. 94

relative humidity............................................................. 17

renovation ..................................................... 13, 14, 23, 37

repairs ............................................................................. 31

reprocess hemodialyzers......................................... 61, 223

research animals............................................................ 111

reservoirs ...................3, 6, 41, 42, 71, 79, 83, 95, 105, 211

resident animals ............................................................ 107

respirable particles.............................................. 27, 28, 90

respirators ................................................................. 26, 40

respiratory protection................................................ 36, 78

respiratory syncytial virus (RSV) ......................... 6, 12, 85

respiratory therapy equipment ...................................... 224

return air ......................................................................... 14

return temperature........................................................... 54

reverse osmosis (RO).............................. 52, 54, 59, 60, 63

rewiring........................................................................... 25

rinse water monitoring.................................................... 70

RODAC plates.............................................................. 102

rodents ............................................................................ 67

rooftops........................................................................... 30

Sabouraud dextrose agar................................................. 96

sample/rinse methods...................................................... 97

sanitary sewer ....................................................... 116, 117

SARS .............................................................................. 86

SARS-CoV ..................................................................... 86

scalding..................................................................... 49, 51

screens ............................................................................ 82

scrub suits ................................................................. 98, 99

sealed windows............................................. 19, 26, 29, 89

sedimentation.................................................... 90, 93, 211

select agents.......................................................... 114, 115

self-closing doors............................................................ 19

semicritical device .......................................................... 70

service animal ............................................... 105, 108–110

settle plates ................................................. 28, 90, 93, 211

sewage spills................................................................... 51

sharps containers........................................................... 113

shock decontamination ................................................... 51

shower heads................47, 49, 54, 220, 221, 222, 224, 225

showers ..................................................................... 47, 48

skin antiseptics................................................................ 73

smallpox.......................................................................... 36

smallpox virus............................................................. 7, 12

smoke tubes ........................................................ 20, 34, 36

sodium hydroxide ........................................................... 87

sodium hypochlorite 67, 69, 73, 77, 83, 84, 87, 88, 94, 225

solid-organ transplant program ....................................... 56

sorting (laundry) ..................................................... 98, 100

Spaulding classification ............................................ 71, 98

spills.................................................................... 75, 77, 79

standard precautions ............................................. 100, 111

standards ....................................2, 14, 71, 88, 90, 112, 223

Staphylococcus aureus

...............10, 11, 38, 64, 73, 99, 104

state codes/regulations .............................................. 55, 69

steam jet........................................................................ 101

steam sterilization (of medical waste)................... 113, 114

sterile water..................................................................... 55

storage tanks ............................................................. 63, 64

streptococci............................................................... 10, 38

supplemental treatment methods..................................... 53

surgical gowns and drapes ............................................ 103

surgical site infections (SSI) ............................... 11, 38, 65

surgical smoke ................................................................ 40

surveillance........................................... 26, 51, 57, 99, 223

swabs ............................................................................ 224

tacky mats....................................................................... 76

tap water ........................................... 42, 44, 57, 65, 66, 70

TB patients...................................................................... 38

temperature (air) ........................................... 13, 14, 17, 89

temperature (water)................40, 45, 49, 68, 101, 221, 227

235

thermostatic mixing valves............................................. 49

transport and storage (of medical waste) ...................... 113

treated items/products............................................. 79, 103

tryptic soy agar ................................................. 94, 96, 222

tub liners......................................................................... 68

tuberculocidal claim ....................................................... 73

tuberculosis (TB) ............................................................ 35

ultrapure dialysate........................................................... 61

ultraviolet germicidal irradiation (UVGI)14, 16, 17, 36, 38

uniforms.................................................................... 98, 99

vacuum breakers....................................................... 47, 50

vacuum cleaners ....................................................... 76, 79

vacuuming ...................................................................... 79

vancomycin-resistant enterococci (VRE) ..3, 5, 82, 83, 105

vancomycin-resistant

Staphylococcus aureus

(VRSA)... 83

variable air ventilation.............................................. 20, 38

varicella-zoster virus (VZV)................................... 5, 7, 40

vase water....................................................................... 81

vegetative bacteria .......................................................... 73

ventilation rates .............................................................. 18

ventilation systems ............................................... 8, 9, 111

viable particles............................................................ 9, 91

viral hemorrhagic fever................................................... 12

viral particles .................................................................. 11

viruses....................................................................... 11, 85

visual monitoring device................................................. 34

volumetric air samplers................................................... 29

volumetric sampling methods......................................... 28

wallboard.............................................................. 8, 22, 52

walls ............................................................................... 25

washing machines and dryers ....................................... 102

water conditioning .......................................................... 68

water distribution systems .............................. 64, 221, 227

water droplets ................................................................. 58

water pipes...................................................................... 46

water pressure................................................................. 50

water quality ............................................................. 71, 94

water sampling.......................................... 54, 94, 221, 224

water stagnation............................................................ 227

water treatment system ................................................... 63

waterborne transmission ................................................. 46

weight-arrestance test ..................................................... 15

wet cleaning.................................................................... 79

whirlpool spas..................................................... 59, 67, 69

whirlpools................................................................. 68, 69

window chutes................................................................ 33

windows.................................................................... 22, 59

wood ................................................................. 8, 9, 15, 35