Medical Air Solutions, LLC

A. Introduction

B. Key Terms Used in this Guideline

C. Air (Refer to CDC 2001 - Air)

D. Water (Refer to CDC 2001 - Water)

E. Environmental Services

1. Principles of Cleaning and Disinfecting Environmental Surfaces

2. General Cleaning Strategies for Patient-Care Areas

a. Strategies for Routine Cleaning of Medical Equipment

b. Strategies for Routine Cleaning of Housekeeping Surfaces

c. Strategies for Cleaning Special-Care Areas

3. Cleaning Strategies for Spills of Blood and Body Substances

4. Carpeting and Cloth Furnishings

a. Carpeting

b. Cloth Furnishings

5. Flowers and Plants in Patient-Care Areas

6. Pest Control

7. Special Pathogen Concerns

1. Antibiotic-Resistant Gram-Positive Cocci
2. b. Clostridium difficile
3. Respiratory and Enteric Viruses in Pediatric Care Settings
4. Creutzfeldt-Jakob Disease (CJD) in Patient-Care Areas

F. Environmental Sampling

1. General Principles - Microbiologic Sampling of the Environment

2. Air Sampling

3. Water Sampling

4. Environmental Surface Sampling

G. Laundry and Bedding

1. General Information

2. Epidemiology and General Aspects of Infection Control

3. Collecting, Transporting, and Sorting Soiled Textiles and Fabrics

4. Parameters of the Laundry Process

5. Special Laundry Situations

6. Surgical Gowns, Drapes and Disposable Fabrics

7. Antimicrobial-Impregnated Articles

8. Standard Mattresses, Pillows, and Air-Fluidized Beds

H. Animals in Healthcare Facilities

1. General Information

2. Pet Visitation, Pet Therapy, and Resident Animals

3. Service Animals

4. Animals as Patients in Human Healthcare Facilities

5. Research Animals in Healthcare Facilities

I. Regulated Medical Waste

1. Epidemiology

2. Categories of Medical Waste

3. Management of Regulated Medical Waste in Healthcare Facilities

4. Treatment of Regulated Medical Waste

5. Discharging Blood, Fluids to Sanitary Sewers or Septic Tanks

6. Medical Waste and CJD

The Guideline for Environmental Infection Control in Healthcare Facilities, 2001 is a compilation of recommendations for the prevention and control of infectious diseases that are linked to healthcare environments. This document: 1) updates and revises several sections (i.e., cleaning and disinfection of environmental surfaces, environmental sampling, laundry and bedding, and regulated medical waste) from the previous editions of the Centers for Disease Control and Prevention [CDC] document entitled Guideline for Handwashing and Hospital Environmental Control;1, 2 2) incorporates discussions of air and water environmental issues from the Guideline for the Prevention of Nosocomial Pneumonia;3 3) consolidates relevant environmental infection control measures from several other CDC guidelines;4 - 9 and 4) discusses two topics not addressed in previous CDC guidelines -- infection control issues related to the presence of animals in healthcare facilities, and water quality in hemodialysis settings.

Part II, "Recommendations for Environmental Infection Control in Healthcare Facilities," presents control measures for preventing infections associated with air, water, or other environmental concerns within healthcare facilities as appropriate. These recommendations represent the consensus of the Healthcare Infection Control Practices Advisory Committee (HICPAC), a 12-member committee that advises CDC on issues related to the surveillance, prevention, and control of healthcare-associated infections primarily in United States healthcare facilities.10 As of January 1999, HICPAC expanded its infection control focus from acute-care hospitals to all venues where healthcare is provided (e.g., outpatient surgical centers, urgent care centers, clinics, outpatient dialysis centers, physicians’ offices, skilled nursing facilities). The topics addressed in this guideline are generally applicable to a variety of healthcare venues throughout the United States. This document is intended for use primarily by infection control practitioners, epidemiologists, employee health and safety personnel, engineers, informational system specialists, administrators, environmental service and housekeeping professionals, and architects for these facilities.

The healthcare environment contains a diverse population of microorganisms, but only a select few are significant pathogens for susceptible humans. Microorganisms are present in great numbers in moist, organic environments, but some can also persist under dry conditions. Although pathogenic microorganisms can be detected in air and water and on fomites, it is difficult to assess their role in causing infection and disease.11

There are few reports which clearly delineate a "cause and effect" with respect to the environment, in particular for the housekeeping surfaces. Seven levels of proof are used to evaluate the strength of evidence for an environmental source or means of transmission of infectious agents.11 In the order of their rigor, these are: 1) the organism can survive after inoculation onto the fomite; 2) the organism can be cultured from in-use fomites; 3) the organism can proliferate in or on the fomite; 4) some measure of acquisition of infection cannot be explained by other recognized modes of transmission; 5) retrospective case-control studies show an association between exposure to the fomite and infection; 6) prospective observational studies may be possible when more than one similar type of fomite is in.6 use; and 7) prospective studies allocating exposure to the fomite to a subset of patients show an association between exposure and infection. An additional level of proof is that decontamination of the fomite results in the elimination of disease transmission.12

Applying these proofs to disease investigations allows scientists to assess the contribution of the environment to disease transmission. The identification of a pathogen (e.g., vancomycin-resistant enterococci [VRE]) on an environmental surface during an outbreak serves as an illustration of this point. The presence of the pathogen does not automatically establish its causal role; its transmission from source to host could be through indirect means, such as via hand transferral.11 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 healthcare-associated disease.13 All of the components of the "Chain" must be operational for infection to occur. That is, infection requires: 1) an adequate number of pathogenic organisms [dosage]; 2) pathogenic organisms of sufficient virulence; 3) a susceptible host; 4) an appropriate mode of transmission or transferral of the organism in sufficient number from a source to the host; and 5) the correct portal of entry into the host. The presence of the susceptible host has focused recent attention on the importance of the healthcare environment and opportunistic pathogens in air and water and on fomites. As a result of advances in medical technology and therapies (e.g., intensification of cytotoxic chemotherapy; progress of transplantation medicine), a greater number of patients are becoming increasingly immunocompromised in the course of treatment and are therefore at increased risk of acquiring healthcare-associated opportunistic infections.

Trends in healthcare delivery are also changing the distribution of patient populations and increasing the number of immunocompromised persons in healthcare settings other than acute-care hospitals, especially in light of early discharge of patients from care. According to the American Hospital Association (AHA), the number of hospitals in the United States in 1998 totaled 6,021, with 1,013,000 beds.14 This represents 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. 14 The total average daily census in U.S. acute-care hospitals in 1998 was 662,000 (65.4%) -- 36.5% less than the average daily census of 1,042,000 in 1978. 14 As the number of acute-care hospitals declines, the length of stay in these facilities is concurrently decreasing, primarily for immunocompetent patients. Those patients remaining in acute-care facilities are likely be those who require extensive medical interventions and are therefore at high risk for opportunistic infection.

The growing population of severely immunocompromised patients is at odds with demands on the healthcare industry to remain viable in the marketplace, to incorporate modern equipment, new diagnostic procedures, treatments, and to construct new facilities. Increasing numbers of healthcare facilities are likely to be faced with some 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 the healthcare construction projects were for renovation or building outpatient facilities;15 the number of outpatient projects rose by 17% between 1998 and 1999. 16 An aging population is also creating increasing demand for assisted-living facilities and skilled nursing centers. Construction of assisted-living facilities in 1998 rose by 49%, with 138 projects completed at a cost of $703 million.16 Overall, from 1998 to 1999, healthcare construction costs increased by 28.5%, from $11.56 billion to $14.86 billion.16

Examples of outbreaks which could have been prevented had this partnership been in place include: 1) transmission of infections due to Mycobacterium tuberculosis, varicella-zoster virus [VZV], and measles [rubeola] virus apparently facilitated by inappropriate air-handling systems in healthcare facilities;6 2) disease outbreaks due to Aspergillus spp.,17 – 19

Mucoraceae,20 and Penicillium spp. associated with the absence of environmental controls during periods of construction;21 3) infections and/or colonizations of patients and staff with vancomycin-resistant Enterococcus faecium [VRE] and Clostridium difficile, presumably acquired in an indirect manner from contact with organisms present on environmental surfaces in healthcare facilities;22 - 25 and 4) outbreaks and pseudoepidemics of legionellae,26, 27 Pseudomonas aeruginosa,28 - 30 and the nontuberculous mycobacteria [NTM]31, 32 linked to water and aqueous solutions in healthcare facilities. The purpose of this guideline is to provide useful information for healthcare professionals and engineers alike in efforts to provide quality healthcare to their patients. The recommendations herein provide guidance to minimize and/or prevent transmission of pathogens in the indoor environment.

E. Environmental Services

Although microbiologically-contaminated surfaces can serve as reservoirs of potential pathogens, these surfaces are generally 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.896, 897

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.898, 899 These categories are "critical," "semi-critical," and "non-critical." In 1991, CDC proposed an additional category designated "environmental surfaces" to Spaulding’s original classification.900 These are non-critical 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, dental units) and housekeeping surfaces (e.g., floors, walls, tabletops).900

Several factors influence the choice of disinfection procedure for environmental surfaces: 1) the nature of the item to be disinfected; 2) the number of microorganisms present; 3) the innate resistance of those microorgansims to the inactivating effects of the germicide; 4) the amount of organic soil present; 5) the type and concentration of germicide used; 6) duration and temperature of germicide contact; and 7) if using a proprietary product, other specific indications for use.901

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.902 - 908 The physical action of scrubbing with detergents and surfactants and rinsing with water removes large numbers of microorganisms from surfaces.905 If the surface is not cleaned before the terminal reprocessing procedures are started, then 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."898, 899 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 32). This information, coupled with the instrument/surface classification, determines the appropriate level of terminal disinfection for an instrument or surface.

Intermediate-level disinfection does not necessarily kill bacterial spores, but does inactivate Mycobacterium tuberculosis var. bovis, which is significantly 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 but are not limited to 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], influenza viruses), and some non-enveloped viruses (e.g., adenoviruses). Low-level disinfectants, which may also be referred to as "sanitizers," include quaternary ammonium compounds, some phenolics, and some iodophors. Germicidal chemicals cleared as skin antiseptics are not appropriate for use as environmental surface disinfectants.900

The selection and use of chemical germicides are guided by product label instructions and information. Sterilant/disinfectant chemicals (i.e., high-level disinfectants) are regulated now exclusively by the FDA as a result of recent memoranda of understanding between FDA and the EPA which delineates agency authority for chemical germicide regulation.909, 910

Environmental surface germicides (i.e., intermediate- and low-level disinfectants) are regulated by the EPA and labeled with EPA registration numbers. The labels and package inserts 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, but does not perform these pre-registration laboratory tests, relying instead on the manufacturer to provide valid data. Germicides labeled as "hospital disinfectant" have passed the potency tests for activity against three representative microorganisms –Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella cholerae suis. Hospital disinfectants with demonstrated potency against mycobacteria (i.e., intermediate-level disinfectants) may list "tuberculocidal" on the label as well. Low-level disinfectants are often labelled "hospital disinfectant" without a tuberculocidal claim, because they lack the potency to inactivate mycobacteria. Other claims, such as "fungicidal," "pseudomonicidal," or "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.900

It is this broad spectrum capability, rather than the product’s specific potency against mycobacteria, that is the basis for protocols and OSHA regulations dictating use of tuberculocidal chemicals for surface disinfection.911

The number and types of microorganisms present on environmental surfaces are influenced by several factors: 1) number of people in the environment; 2) amount of activity; 3) amount of moisture; 4) presence of material capable of supporting microbial growth; 5) rate at which organisms suspended in the air are removed; and 6) type of surface and orientation [horizontal or vertical].912 Strategies for cleaning and disinfecting surfaces in patient-care areas take into account: 1) potential for direct patient contact; 2) degree and frequency of hand contact; and 3) potential contamination of the surface with body substances or environmental sources of microorganisms (e.g., soil, dust, or water).

Manufacturers of medical equipment should provide care and maintenance instructions specific to their equipment. These instructions should include information about materials compatibility with chemical germicides, whether or not the equipment can be safely immersed for cleaning, and how the equipment should be decontaminated if servicing is required.911 In the absence of manufacturers’ instructions, non-critical medical equipment (e.g., stethoscopes, blood pressure cuffs, dialysis machines, equipment knobs and controls) usually need only cleaning followed by low- to intermediate-level disinfection depending on the nature and degree of contamination. Ethyl alcohol or isopropyl alcohol in concentrations ranging from 60% to 90% is often used to disinfect small surfaces (e.g., rubber stoppers of multiple-dose medication vials, thermometers)901, 913 and external surfaces of equipment (e.g., stethoscopes, ventilators) on occasion. However, alcohol evaporates rapidly, which makes extended contact times difficult to achieve unless items are immersed, a factor which precludes its practical use as a large surface disinfectant.901 Alcohol may cause discoloration, swelling, hardening, and cracking of rubber and certain plastics after prolonged and repeated use, and damage the shellac mounting of lenses in medical equipment.914

Barrier protection of surfaces and equipment is useful, especially if these surfaces are: 1) touched frequently by gloved hands during the delivery of patient care; 2) likely to become contaminated with body substances; or 3) difficult to clean. Impervious-backed paper, aluminum foil, 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.892 Coverings should be removed and discarded while the healthcare worker is still gloved.892 The healthcare worker, after ungloving and hand hygiene, covers these surfaces with clean materials before the next patient encounter.

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.897, 915, 916 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 hospital, type of surface to be cleaned, and the amount and type of soil present. Disinfectant-detergent formulations registered by the EPA are used for environmental surface cleaning, but the actual physical removal of microorganisms and soil by scrubbing is probably as important, if not more so, than any antimicrobial effect of the cleaning agent used.917 Therefore, cost, safety, 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. Consult the products’ material safety data sheets (MSDS) to determine appropriate precautions to prevent hazardous conditions during product application.

Housekeeping surfaces can be divided into two groups - those with minimal hand-contact (e.g., floors, ceilings), and those with frequent hand-contact ("high touch surfaces"). The methods, thoroughness, and frequency of cleaning and the products used are determined by healthcare facility policy.6 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) 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, 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.6 Regular cleaning of surfaces and decontamination as needed is also advocated to protect potentially exposed workers.911 Cleaning of walls, blinds, and window curtains is recommended when they are visibly soiled.916, 917 Disinfectant fogging is not recommended for general infection control in routine patient-care areas.2

Extraordinary cleaning and decontamination of floors in healthcare settings is unwarranted. Studies have demonstrated that disinfection of floors offers no significant advantage over regular detergent/water cleaning and has little or no impact on the occurrence of healthcare-associated infections.896, 897, 919 - 921 Additionally, newly cleaned floors become rapidly recontaminated from airborne microorganisms and those transferred from shoes, equipment wheels, and body substances.915, 919, 922 Methods for cleaning non-porous floors include wet mopping and wet vacuuming, dry dusting with electrostatic materials, and spray buffing.917, 923 - 925 Methods that produce minimal mists and aerosols or dispersion of dust in patient-care areas are preferred.9, 20, 109, 262

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.915, 922, 926 Cleaning solutions should be replaced frequently. A variety of "bucket" methods have been devised to address the frequency with which cleaning solutions are replaced.927, 928 Another source of contamination in the cleaning process is the cleaning cloth or mop head, especially if left soaking in dirty cleaning solutions.915, 929 - 931 Laundering of cloths and mop heads after use, and allowing them to dry before re-use, can help to minimize the degree of contamination.931 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.932 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 and stored for long periods of time. Gram-negative bacilli (e.g., Pseudomonas spp.) have been detected in working solutions of some disinfectants (e.g., phenolics).933

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.934, 935 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 (e.g., quart-sized dishwashing liquid bottles) which dispense liquid as opposed to spray-nozzle dispensers may 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.

Guidelines have been published on cleaning strategies for isolation areas and for the operating rooms.6, 7 The basic strategies for areas housing immunosuppressed patients include: 1) wet dusting horizontal surfaces daily with cleaning cloths pre-moistened with a hospital disinfectant; 94, 927 2) using care when wet dusting equipment and surfaces above the patient to avoid patient contact with the detergent/disinfectant; 3) avoiding the use of cleaning equipment that produces mists or aerosols; 4) equipping vacuums with HEPA filters, especially for the exhaust, for use in any patient-care area where immunosuppressed patients;9, 94, 927 and 5) regular cleaning and maintenance of equipment to ensure efficient particle removal. Dispersal of microorganisms in the air from dust or aerosols can be problematic in these settings than elsewhere in the facility. There is the potential for vacuum cleaners to serve as dust disseminators if they are not operating properly.936 Doors to patients’ rooms should be closed when vacuuming anywhere in patient-care areas where immunosuppressed patients are located.9 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.

Tacky mats in operating rooms and other patient-care areas do little to minimize the overall degree of contamination of floors, and have little impact on the incidence rate of healthcare-associated infection in general.340, 915, 924 An exception to this statement is the use of tacky mats inside the entry ways of cordoned-off construction areas inside the healthcare 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.937 –939

These medical conditions have not, however, been associated with the use of properly prepared use-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, and can be an option among available hospital disinfectants.939

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.939 If phenolics are used for terminal cleaning of bassinets and incubators, the surfaces should be rinsed thoroughly with water and dried before reused of either piece of equipment. Cleaning and disinfecting protocols should allow for the full contact time specified for the product used. Bassinette mattresses should be replaced, however, if the mattress cover surface is broken.939

There is no evidence that either HBV, HCV, or 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.911

Studies have shown that HIV is inactivated rapidly after being exposed to commonly used chemical germicides at concentrations that are much lower than those used in practice.940 - 945 HBV is readily inactivated with a variety of germicides, including quaternary ammonium compounds.946 Embalming fluids (e.g., formaldehyde) are also capable of completely inactivating HIV and HBV.947, 948 In addition to commercially available germicides registered for use as "hospital disinfectants" with a tuberculocidal claim (i.e., intermediate-level disinfectants), a solution of sodium hypochlorite (household chlorine bleach) prepared daily is an inexpensive and effective broad-spectrum germicide.

Concentrations of sodium hypochlorite solutions ranging from approximately 5,000 ppm (1:10 dilution of household bleach) to 500 ppm (1:100 dilution) free chlorine are effective depending on the amount of organic material (e.g., blood, mucus, urine) present on the surface to be cleaned and disinfected.949, 950 Commercially available chemical germicides may be more compatible with certain materials that might be corroded by repeated exposure to sodium hypochlorite, especially the 1:10 dilution. Appropriate personal protective equipment (e.g., gloves, goggles) should be worn when preparing hypochlorite solutions.911

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.949 In patient-care areas, workers can manage small spills with a one-step procedure.927, 928 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.944, 945, 951 If the surface is nonporous and the germicide of choice is household bleach, then a 1:100 dilution is appropriate for the decontamination step. This assumes, however, that: 1) the worker assigned to clean the spill is wearing gloves and other personal protective equipment appropriate to the task; 2) the majority of the organic matter of the spill has been removed with absorbent material; and 3) the surface has been cleaned to remove residual organic matter. A recent study showed 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.950 This supports the need to remove the majority of 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.900, 902

Managing spills of blood, body fluids, or other infectious materials in clinical, public health, and research laboratories requires more stringent measures because of the higher potential risk of disease transmission associated with large volumes of blood and body fluids, and high numbers of microorganisms associated with diagnostic cultures. The use of an intermediate-level germicide for routine decontamination in the laboratory is prudent.902 Recommended practices for managing large spills of concentrated infectious agents in the laboratory include: 1) confining the contaminated area; 2) flooding the area with a liquid chemical germicide before cleaning; and 3) decontaminating with fresh germicidal chemical of at least intermediate-level disinfectant potency.949 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.952 If using a solution of household chlorine bleach, a 1:10 dilution is recommended for this purpose. Commercial 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. Personal protective equipment in such a situation may include the use of respiratory protection (e.g., N95 respirator) if clean-up procedures are expected to generate infectious aerosols. Protocols for cleaning spills should be developed and on record as part of good laboratory practice.952

Carpeting has been used for over 30 years in both public and patient-care areas of healthcare facilities. Advantages of carpeting in patient-care areas include: 1) its noise-limiting characteristics; 2) the "humanizing" effect on health care; and 3) its contribution to reductions in falls and resultant injuries, particularly for the elderly.953 - 955 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 on carpeting (e.g., wheelchairs, carts, gurneys).

Several studies have documented the presence of diverse microbial populations, primarily bacteria and fungi, in carpeting.111, 956 - 963 The variety and number of microorganisms tend to be stable over. New carpeting quickly becomes colonized, with bacterial growth plateauing after about four weeks.958 Additionally, vacuuming and cleaning the carpeting can temporarily reduce the numbers of bacteria, but these populations soon rebound and return to pre-cleaning levels.958, 959, 962 Bacterial contamination tends to increase with higher levels of activity.957 - 959, 964 Soiled carpeting that is or remains damp or wet provides an ideal setting for the proliferation and persistence of gram-negative bacteria and fungi. Carpeting that remains in this condition should be removed.

Despite the evidence of bacterial growth and persistence in carpeting, there is little epidemiologic evidence to show that carpets influence healthcare-associated infection rates in areas housing immunocompetent patients.962, 964 This guideline, therefore, includes no recommendations against the use of carpeting in these areas. Nonetheless, it is reasonable to avoid the use of carpeting in areas where spills are likely to occur (e.g., laboratories, areas around sinks, janitor closets) and where patients may be at greater risk of infection from airborne environmental pathogens (e.g., HSCT units, burn units, intensive care units, operating rooms).111, 966 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 in efforts 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, 936 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, 927 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.967 Cleaning equipment, especially those that do 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. Use of such equipment then may transfer large numbers of bacteria to carpeting during the cleaning process.968 It is, therefore, important to keep the carpet cleaning equipment in good repair, and to allow the unit to dry out between uses if so indicated by the manufacturer.

General carpet cleaning should be performed on a regular basis determined by internal policy, although spills of blood and body substances require prompt spot cleaning using standard cleaning procedures and application of chemical germicides.911 Most, if not all, modern carpet brands suitable for public facilities are able to tolerate the activity of a variety of liquid chemical germicides. However, OSHA considers that, compared to nonporous floor surfaces, carpeting contaminated with blood or other potentially infectious materials cannot be fully decontaminated.969 To comply with the intent of this interpretation, facilities electing to use carpeting for high-activity patient-care areas may choose carpet tiles in areas at high risk for spills.911, 969 In the event of contamination with blood or other body substances, carpet tiles can be removed, discarded, and replaced.

Over the last few years, some carpet manufacturers have treated their products with fungicidal and/or bacteriocidal 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 healthcare-associated aspergillosis rates low in one HSCT unit,111 but overall there is no indication that use of treated carpeting will prevent the incidence of healthcare-associated infections in care areas for immunocompetent patients.

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.970 Even though pathogenic microorganisms have been isolated from the surfaces of cloth chairs, there is no epidemiologic evidence that general patient-care areas with cloth furniture have increased rates of healthcare-associated infection compared to areas with hard-surfaced furniture.971, 972 Allergens, such as dog or cat dander, have been detected in or on cloth seating in clinics and elsewhere in hospitals in concentrations higher than that found on bed linens.973, 974 These are presumably 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 healthcare-associated, environmental airborne disease.9, 20, 109, 929 At present it is reasonable to minimize the use of upholstered furniture and furnishings in any patient-care areas where immunosuppressed patients are located (e.g., HSCT units).9

Fresh flowers, dried flowers, and potted plants are common items in healthcare facilities. In 1974, clinicians isolated an Erwinia sp. post mortem from a neonate diagnosed with fulminant septicemia, meningitis, and respiratory distress syndrome.975 Since Erwinia spp. are plant pathogens, plants brought into the delivery room were suspected as the source of the bacteria, although the case report did not definitively establish a direct link. A number of 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 4 - 10 10 CFU/mL, were often present, especially if the water was changed infrequently.495, 670, 976 The major group of microorganisms in flower vase water was gram-negative bacteria, with Pseudomonas aeruginosa the most frequently isolated organism.495, 670, 976, 977 P. aeruginosa was also the major organism directly isolated from chrysanthemums and other potted plants.978, 979 However, flowers in hospitals were not significantly more contaminated with bacteria compared to flowers in restaurants or in the home.670 Additionally, there were no differences in the diversity and degree of antibiotic resistance of bacteria isolated from hospital flowers compared to bacteria from flowers elsewhere.670

Despite the diversity and large numbers of bacteria associated with flower vase water and potted plants, there is little or no evidence to indicate that the presence of plants in immunocompetent patient-care areas poses an increased risk of healthcare-associated infection.495 In one small study among surgical patients, no correlation was observed between bacterial isolates from flowers in the area with the incidence and etiology of postoperative infections among the patients.977 Similar conclusions were reached in a study which looked at the bacteria of potted plants.979 Nonetheless, it is prudent to implement some precautions for general patient-care settings, such as: 1) limiting flower and plant care to staff with no direct patient contact; 2) if this is not feasible, then advising healthcare staff to wear gloves when handling plants; 3) washing hands after handling plants; 4) changing vase water every two days and discharging the water into a sink outside the immediate patient environment; and 5) cleaning and disinfecting vases after use.670

Some researchers have looked into the possibility of adding a chemical germicide to vase water to control bacterial populations. Chemicals such as hydrogen peroxide and chlorhexidine appear to be reasonably well tolerated by plants.977, 980, 981 Use of these chemicals, however, was not evaluated in studies to assess impact on healthcare-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 is a strong possibility.109 Healthcare-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. Both 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, 982 Researchers in one of the small studies 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, transplant patients), although this study did not attempt to correlate the observations of bacterial populations in the vase water with the incidence of healthcare-associated infections.495 It is therefore reasonable to exclude flowers and plants from areas where immunosuppressed patients may be located (e.g., HSCT units).9

Cockroaches, flies and maggots, ants, mosquitos, spiders, mites, midges, and mice are among the typical arthropod and vertebrate pest populations found in healthcare 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.983 - 985 Arthropods recovered from healthcare facilities have been shown to carry a wide variety of pathogenic microorganisms.986 – 992

Studies have suggested that the diversity of microorganisms associated with insects reflects the microbial populations present in the indoor healthcare environment; some pathogens encountered in insects from hospitals were either absent from or present to a lesser degree in insects trapped from residential settings.993 - 996 Some of the microbial populations associated with insects in hospitals have demonstrated resistance to antibiotics.984, 995, 997, 998

Insect habitats are characterized by warmth, moisture, and availability of food.999 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.993 - 997 Cockroaches, in particular, have been known to feed on fixed sputum smears in laboratories.1000, 1001 Both cockroaches and ants are frequently found in the laundry, central sterile supply departments, or anywhere in the facility where water or moisture is present (e.g., sink traps, drains, janitor closets). Ants will often find their way into sterile packs of items as they forage in a warm, moist environment.993 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 largely circumstantial, especially in healthcare settings; insects do not appear to play a major or singular role in healthcare-associated disease transmission in developed countries. Some studies have been conducted to examine the role of houseflies as possible vectors for shigellosis and other forms of diarrheal disease in non-healthcare settings.983, 1002 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 due to diarrhea among infants and young children were observed.

From a public health and hygiene perspective, it is reasonable to control and eradicate arthropod and vertebrate pests from all indoor environments, including healthcare facilities.1003, 1004 Modern approaches to institutional pest management usually focus on: 1) eliminating food sources, indoor habitats, and other conditions that attract pests; 2) excluding pests from the indoor environments; and 3) applying pesticides as needed.1005 Sealing windows in modern healthcare 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 need to be kept out of all areas of the healthcare facility, but this is especially important for the operating rooms 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.

Vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), and S. aureus with intermediate levels of resistance to glycopeptide antibiotics (VISA or GISA) represent serious and increasing concerns for infection control. While 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.1006

According to National Nosocomial Infection Surveillance (NNIS) statistics for infections acquired among intensive care unit patients in the United States in 1999, 52.3% of infections due to 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- 98. 1007

People represent the major reservoir of S. aureus.1008 Although S. aureus has been isolated from a variety of environmental surfaces (e.g., stethoscopes, floors, charts, furniture, dry mops, hydrotherapy tanks), the role of environmental contamination in transmission of this organism appears to be minimal.1009 - 1012 S. aureus contamination of surfaces and tanks within burn therapy units, however, may be important in the transmission of infection among burn patients.1013

The colonized patient is the principal reservoir of VRE, and patients who are immunosuppressed (e.g., transplant patients) or otherwise medically at-risk (e.g., intensive care unit patients, cardio-thoracic surgical patients, patients previously hospitalized for extended periods, or those having received multi-antimicrobial or vancomycin therapy) appear to be at greatest risk for VRE colonization.1014 - 1017 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: 1) directly from patient to patient; 2) indirectly by transient carriage on the hands of healthcare workers;1018 - 1021 or 3) by hand transfer of these gram-positive organisms from contaminated environmental surfaces and patient-care equipment.1014, 1017,1022 - 1027 In one survey, hand carriage of VRE in workers in a long-term care facility ranged from 13 - 41%.1028

Many of the environmental surfaces found to be contaminated with VRE in outbreak investigations have been those which are touched frequently by the patient or the healthcare worker.1029 Such high-touch surfaces include, but are not limited to bedrails, doorknobs, bed linens, gowns, overbed tables, blood pressure cuffs, computer table, bedside tables, and various medical equipment.22, 1017, 1024, 1025, 1030 Contamination of environmental surfaces with VRE generally occurs in areas where colonized patients are present,1017, 1022, 1024, 1025 but the potential for contamination increases when such patients have diarrhea,1017 or have multiple body site colonization.1031 Additional factors which can be important in the dispersion of these pathogens to environmental surfaces are misuse of glove techniques by healthcare workers, especially when cleaning fecal contamination from surfaces; and patient, family, and visitor hand hygiene and personal 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)1029, 1032 and multiple strains can be identified during extensive periods of surveillance.1031 VRE can be recovered from inoculated hands of healthcare workers (with or without gloves) for up to 60 minutes.22 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 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.5

Careful cleaning of patient rooms and medical equipment is important to the overall control of MRSA, VISA, or VRE transmission, but should not be the major focus of a control program for either VRE or MRSA. Routine cleaning and disinfection of the housekeeping surfaces (e.g., floors, walls) and patient-care surfaces (e.g., bedrails) should be adequate for inactivation of these organisms. Both MRSA and VRE are susceptible to a variety of low- and intermediate-level disinfectants such as alcohols and sodium hypochlorite; quaternary ammonium compounds, phenolics, and iodophors at recommended use dilutions for environmental surface disinfection.1033 - 1036 Additionally, both VRE and vancomycin-sensitive enterococci appear to be equally sensitive to inactivation by chemical germicides,1033, 1034, 1036 and similar observations have been made when comparing the germicidal resistance of MRSA to that of either methicillin-sensitive S. aureus (MSSA) or VISA.1037 There is no indication for using stronger solutions of disinfectants for inactivation of either VRE, MRSA, or VISA because of the organisms’ resistance to antibiotics.1037, 1038

VRE from clinical specimens have exhibited some measure of increased tolerance to heat inactivation in temperature ranges <100°C (<212°F),1033, 1039 but the clinical significance of these observations is unclear because the role of cleaning the surface or item prior to heat treatment wasn’t 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.1014, 1017, 1018, 1022,1026

One concern is that standard procedures during terminal cleaning and disinfection of surfaces may be inadequate for the elimination of VRE from patient rooms.1039 - 1042 Given the sensitivity of VRE to hospital disinfectants, current disinfecting protocols should be effective if they are diligently carried out and properly performed. Healthcare facilities should be sure that housekeeping staff use correct procedures for cleaning and disinfecting surfaces in VRE-contaminated areas. These include using sufficient amounts of germicide at proper use dilution and adequate contact time of the surface with the germicide liquid.1042

Clostridium difficile is the most frequent etiologic agent for healthcare-associated diarrhea.1043, 1044 In one hospital, 30% of adults who developed healthcare-associated diarrhea were postive for C. difficile.1045 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: 1) exposure to antibiotic therapy, particularly with $-lactam agents;1046 2) gastrointestinal procedures and surgery;1047 3) advanced age; and 4) indiscriminate use of antibiotics.1048 - 1051 Of all the measures that have been used to prevent the spread of C. difficile-associated diarrhea, the most successful measure has been the restriction of the use of antimicrobial agents.1052, 1053

Clostridium 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, on dry surfaces) for extended periods of time. Environmental contamination by this microorganism is well known, especially wherever fecal contamination may occur.1054 There is little evidence, especially for housekeeping surfaces (e.g., floors, walls), that the environment is a direct source of infection for patients.963, 1055 - 1059 However, direct exposure to contaminated patient-care items (i.e., rectal thermometers) and high-touch surfaces in patients’ bathrooms have been implicated as sources of infection.1053, 1058, 1060, 1061

Transfer of the pathogen to the patient via the hands of healthcare workers is thought to be the most likely mechanism of exposure.24, 1056, 1062 Standard isolation techniques intended to minimize enteric contamination of patients, healthcare worker hands, patient-care items, and environmental surfaces have been published.926 Handwashing remains the major 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, 1055, 1058 although asymptomatic, colonized patients may also serve as a source of contamination. Few studies have examine the use of specific chemical germicides for the inactivation of C. difficile spores, and no well-controlled trials to determine efficacy of surface disinfection and its impact on healthcare-associated diarrhea have been conducted. Some investigators have evaluated the use of chlorine-containing chemicals (e.g., 1:100 dilutions of unbuffered hypochlorite, phosphate-buffered hypochlorite [1600 ppm]), and showed that the number of contaminated environmental sites was reduced by half.1058 The recommended approach to environmental infection control with respect to C. difficile is meticulous cleaning and disinfection using proper use dilutions and contact times for environmental surface germicides as appropriate.901, 1053, 1063

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. Since transmission primarily requires close personal contact, contact precautions are appropriate to interrupt transmission.6 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 efficiency of the latter form of transmission is dependent on the ability of these viruses 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.1064 Parainfluenza viruses are known to persist for up to 4 hours on porous surfaces and up to 10 hours on non-porous surfaces.1065 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.1066 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 is primarily fecal-oral. 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.1067, 1068 In an outbreak in a pediatric unit, secondary cases of rotavirus infection tended to cluster in areas where children with rotaviral diarrhea were located.10693

Outbreaks of small round-structured viruses (i.e., caliciviruses [Norwalk virus and Norwalk-like viruses]) can affect both patients and staff, with attack rates >50%.1070 Routes of person-to-person transmission include fecal-oral spread and aerosols from vomiting.1071 - 1073 Fecal contamination of surfaces in care settings may potentially spread large amounts of either virus to the environment. Studies which have attempted to use low- and intermediate-level disinfectants to inactivate rotavirus suspended in feces have demonstrated the protective effect of high concentrations of organic matter.1074, 1075 Intermediate-level disinfectants (e.g., alcoholic quaternary ammonium compounds, chlorine solutions) can be effective in inactivating enteric viruses provided that a cleaning step to remove most of the organic matter precedes terminal disinfection.1075 These findings underscore the need for proper cleaning and disinfecting procedures where contamination of environmental surfaces with body substances is likely. Using disposable, protective barrier coverings may help to minimize the degree of surface contamination.892

Creutzfeldt-Jakob disease (CJD) is a rare, invariably fatal, transmissible spongiform encephalopathy (TSE) occurs worldwide with an average annual incidence of 1 case per million population.1076 - 1078 CJD is one of several TSEs affecting humans; others 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. 1079 This variant form of CJD (vCJD) is clinically and neuropathologically distinguishable from classic CJD, and there is strong epidemiologic and laboratory evidence which suggests a causal association between bovine spongiform encephalopathy (BSE [Mad Cow disease]) and vCJD.1079 – 1082

The agent associated with CJD is a prion, which is an abnormal isoform of a normal protein constituent of the central nervous system.1083 - 1085 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.1086, 1087

Designated iatrogenic cases, these have been linked to pituitary hormone therapy,1088 - 1090 transplants of either dura mater or corneas,1091 - 1097 or neurosurgical instruments and depth electrodes.1098 - 1101 In the cases involving instruments and depth electrodes, inadequate cleaning and terminal reprocessing of these devices failed to fully inactivate the contaminating prions.

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.1086, 1102 –1107

The application of these findings to environmental infection control in healthcare settings is problematic. 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.1108 Additionally, the experimental design of these studies preclude the evaluation of surface cleaning as a part of the total approach to pathogen inactivation.1108

Some researchers have recommended the use of 1:2 to full-strength sodium hypochlorite (20,000 - 50,000 ppm) or 1-2 N sodium hydroxide (NaOH) for the inactivation of prions on surfaces, such as in the pathology laboratory.1086, 1104

Environmental infection control strategies need to be based on the principles of the "Chain of Infection," regardless of the disease of concern.13 Although CJD is transmissible, it is not highly contagious. To date, 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. There is no evidence to date that vCJD has been transmitted iatrogenically. There is no evidence that either CJD or vCJD has been transmitted from environmental surfaces such as the housekeeping surfaces. Therefore, routine procedures are adequate for terminal cleaning and disinfection of a CJD patient’s room. Additionally, epidemiologic studies on highly transfused patients indicate that blood does not appear to be an source for prion transmission.1109 - 1114 Routine procedures for containing, decontaminating, and disinfecting surfaces with blood spills should be adequate for proper infection control in these situations. Guidance for environmental infection control in operating rooms and autopsy areas has been published.1113,

1114 Disposable, impermeable coverings should be used during autopsies to minimize surface contamination. Surfaces that have become contaminated with central nervous system tissue or cerebral spinal fluid should be cleaned and decontaminated by: 1) removing the majority of the tissue or body substance with absorbent materials; 2) wetting the surface with a sodium hypochlorite solution containing minimally >20,000 ppm (e.g., a 1:2 dilution at a minimum) or a 1 - 2 N NaOH solution for 1- 2 hours; and 3) rinsing thoroughly.1113, 1114

Before 1970, U.S. hospitals conducted regularly scheduled culturing of the air and environmental surfaces such as floors, walls, and table tops.1115 By 1970, CDC and the American Hospital Association (AHA) were advocating the discontinuation of routine environmental culturing because rates of healthcare-associated infection had not been related to levels of general microbial contamination of air or environmental surfaces, and meaningful standards for permissible levels of microbial contamination of environmental surfaces or air did not exist.1116 - 1118 Between 1970 and 1975, 25% of U.S. hospitals reduced the extent of such routine environmental culturing; this trend has continued since then.1119, 1120

Random, undirected sampling (referred to as "routine" in previous guidelines) differs from the current practice of targeted sampling for defined purposes.2, 1117 Previous recommendations against routine sampling were not intended to discourage the use of sampling for which sample collection, culture, and interpretation are conducted in accordance with defined protocols.2 In this guideline, targeted microbiological sampling connotes a monitoring process that includes: 1) a written, defined, multidisciplinary protocol for sample collection and culturing; 2) analysis and interpretation of results using scientifically determined or anticipatory baseline values for comparison; and 3) expected actions based on the results obtained.

Microbiological sampling of air, water, and inanimate surfaces (i.e., environmental sampling) is an expensive and time-consuming process which is complicated by many variables in protocol, analysis, and interpretation. It is therefore indicated for only four situations.1121 The first is to support of an investigation of an outbreak of disease or infections when environmental reservoirs or fomites are implicated epidemiologically in disease transmission.159, 1122, 1123 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, 1124, 1125 Linking microorganisms from environmental samples with clinical isolates by molecular epidemiology is crucial.

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 healthcare-associated diseases.126, 129 A classic example is the study of environmental microbial contamination that compared healthcare-associated infection rates in an old hospital and a new facility before and shortly after occupancy.896

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: 1) detect bioaerosols released from the operation of healthcare equipment [e.g., an ultrasonic cleaner] and determine the success of repairs in containing the hazard;1126 2) detect the release of an agent of bioterrorism in an indoor environmental setting, and determine its successful removal or inactivation; and 3) sample for industrial hygiene or safety purposes (e.g., monitor a "sick building").

The fourth indication is for quality assurance to evaluate the effects of a change in infection control practice or 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 is that the effect will be measured over a finite period, usually of short duration. In general conducting quality assurance sampling on an extended basis, especially in the absence of an adverse outcome, is unjustified. A possible exception to this statement 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 healthcare-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.50 Other examples of sampling for quality assurance purposes may include commissioning newly constructed space in special care areas (i.e., operating rooms, units for immunosuppressed patients) or assessing a change in housekeeping practice.

With respect to the second of the instances mentioned above, the only routine environmental microbiologic sampling generally recommended as part of a quality assurance program is the biological monitoring of sterilization processes by using bacterial spores,1127 and monthly cultures 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.250 Certain equipment in healthcare settings (e.g., biological safety cabinets), may also be monitored with air flow and or particulate sampling for performance or as part of compliance with a certification program, comparing the results to a predetermined standard of performance. These measurements, however, do not normally involve microbiologic testing.

Biological contaminants occur in the air as aerosols, and may include bacteria, fungi, viruses, and pollens.1128, 1129

Aerosols are characterized as solid or liquid particles suspended in air. Talking for five 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, 1130 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 are probably 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: 1) the suspending medium; 2) temperature; 3) relative humidity; 4) oxygen sensitivity; and 5) exposure to UV or electromagnetic radiation.1128 Many vegetative cells ordinarily will not survive very long 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).1129 Pathogens which resist drying (e.g., Staphylococcus spp., Streptococcus spp., fungal spores) will survive for relatively long periods and can be carried considerable distances while still viable. They may also settle on surfaces and become airborne again as secondary aerosols during activities such as sweeping and bed making.1128, 1131

Microbiologic air sampling is used as needed to determine the numbers and types of microorganisms, or particulates in indoor air.278 Air sampling for quality control is, however, problematic due to 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 characterized.

Table 33 summarizes the preliminary concerns when designing a microbiologic air sampling strategy. Because the amount of particulate material and bacteria retained in the respiratory system is largely dependent on the size of the inhaled particles, some thought should be given to a determination of particle size 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.1132 Particles <5 µm in diameter reach the lung, but the greatest retention in the alveoli is of particles 1-2 µm in diameter.1133 – 1135

The basic methods include: 1) impingement in liquids; 2) impaction on solid surfaces; 3) sedimentation; 4) filtration; 5) centrifugation; 6) electrostatic precipitation; and 7) thermal precipitation.1131 Of these, impingement in liquids, impaction on solid surfaces, and sedimentation (settle plates) have been used for various air sampling purposes in healthcare settings.278

Table 34. Air Sampling Methods and Equipment 278, 1131, 1136, 1137

Table 35. Factors in Selecting an Air Sampling Device 1131

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.278 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 3 ).

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 samples such as sieve 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.1138

The use of settle plates (sedimentation or depositional method) is not generally recommended when sampling air for fungal spores since single spores can remain suspended in air indefinitely.278 Settle plates have been used mainly to sample for particulates and bacteria, either in research studies or during epidemiologic investigations.159, 1139 - 1142 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); the method cannot quantify the volume of air sampled. Since the survival of microorganisms during air sampling is inversely proportional to the velocity at which the air is taken into the sampler,1128 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 all situations.

A detailed discussion of the principles and practices of water sampling has been published.895 Water sampling in healthcare settings is used as needed to detect waterborne pathogens of healthcare concern or to determine the quality of finished water in a facility’s distribution system. Routine testing of the water in a healthcare facility is usually not indicated, but sampling in support of outbreak investigations can help determine appropriate infection control measures.

Since most water sampling in healthcare facilities involves the testing of finished water from the facility’s distribution system, a reducing agent (i.e., sodium thiosulfate [Na2S2O3]) 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., screen, aerator) must be removed, and hot and then cold water must be run through the tap before collecting the sample.895 If the cleanliness of the tap is questionable, disinfection with 500 ppm sodium hypochlorite (1:100 dilution of chlorine bleach) and flushing the tap should precede sample collection.

Incubation temperatures should be closer to the ambient temperature of the water rather than at 37°C (98.6°F), and recovery media should be formulated to provide appropriate concentrations of nutrients to support organisms exhibiting less than rigorous growth.895 High-nutrient content media (e.g., blood agar, tryptic soy agar [TSA]) may actually inhibit the growth of these damaged organisms. Reduced nutrient media (e.g., diluted peptone, R2A) are preferable for recovery of these organisms.895

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), then assaying small quantities using pour plates or spread plates is appropriate.895 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.

Routine environmental surface sampling (e.g., surveillance cultures) in healthcare settings is neither cost-effective nor warranted.1138, 1143 When indicated, surface sampling should be conducted with multidisciplinary approval in adherence to carefully considered plans of action and policy; items that should be discussed prior to undertaking any sampling process are summarized in Table 36.

Table 36. Considerations before Undertaking Environmental Surface Sampling 1127

Surface sampling is currently use 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: 1) potential environmental reservoirs of pathogens;542, 1144 - 1146 2) survival of microorganisms on surfaces;1146, 1147 or 3) the sources of the environmental contamination.962 Some or all of these approaches can also be used during outbreak investigations.1146 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.1127 The media, reagents, and equipment required for surface sampling are usually 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, 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 requires 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.1127, 1148 - 1150 Dilution fluids and rinse fluids include various buffers or general purpose broth media (Table 37). If disinfectant residuals are expected on surfaces being sampled, then the use of specific neutralizer chemicals 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 already been published.1127, 1152

Table 37. Examples of Eluents and Diluents for Environmental Surface Sampling 1127, 1151

Note: A surfactant such as polysorbate (Tween® 80) may be added to eluents and diluents. A concentration in the range of 0.01% -0.1% is generally used, depending on the specific application. Foaming may occur.

Alternatively, instead of adding neutralizing chemicals to existing culture media, or if the chemical nature of the disinfectant residuals is unknown, then the use of either commercially-available media including a variety of specific and non-specific neutralizers, or even 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 due to the presence of neutralizer chemicals carried over into the assay system.1127

Methods for collecting environmental surface samples are summarized in Table 38. Specific step-by-step discussions of each of the methods have been published.1127, 1153 For best results, all methods should incorporate aseptic techniques, sterile equipment, and sterile recovery media.

* RODAC = 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.1151 Additionally, there should be no microbiocidal or microbiostatic agents present in any of these items when used for sampling.1151 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, or ultrasonic bath) will help to remove and suspend material from the sampling device and break up clumps of organisms for a more accurate count.1151

In some instances, the item used to sample the surface (e.g., gauze pad, sponge) may be immersed in the rinse fluids in a sterile bag and subjected to stomaching.1151 This technique, however, is suitable only for soft or absorbent items so that the bag is not punctured 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.1127

When interpreting the results of the sampling, it is important to consider the expected degree of microbial contamination associated with the various categories of surfaces in the Spaulding classification. Environmental surfaces should be visibly clean; recognized pathogens in numbers sufficient to theoretically contribute to secondary transfer to other animate or inanimate surfaces should be absent from the surface being sampled.1127 Although the interpretation of a sample with positive microbial growth is self-evident, an environmental surface sample showing no growth does not represent a "sterile" surface, especially where housekeeping surfaces are concerned. 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 to rule out extraneous contamination of the surface sample.

Laundry in a healthcare facility consists of bedsheets and blankets, towels, personal clothing, uniforms, scrub suits, gowns, and drapes for surgical procedures.1159 Although soiled textiles and fabrics in healthcare facilities can be a source of large numbers of pathogenic microorganisms, reports of healthcare-associated diseases linked to soiled fabrics are so few in number that the overall risk of disease transmission during the laundry process appears to be negligible. When the incidence of such events are evaluated in the context of the volume of items laundered in healthcare settings (estimated to be 5 billion pounds annually in the United States),1160 it is apparent that existing control measures are effective in reducing the risk of disease transmission to patients and staff. Therefore, it is reasonable to encourage the continued use of current control measures to minimize the contribution of soiled laundry to the incidence of healthcare-associated infections. The control measures described here are based on principles of hygiene and common sense and pertain to laundry services utilized by healthcare facilities, either in-house or contract, rather than to laundry done in the home.

Soiled textiles and fabrics often contain high numbers of microorganisms from body substances including, but not limited to blood, skin, stool, urine, vomitus, and other body tissues and fluids. When linen is heavily contaminated with potentially infective body substances, it can contain bacterial loads of 10 6 - 10 8 CFU/100 cm 2 of fabric.1161 Infectious disease transmission attributed to healthcare laundry involved soiled fabrics which were handled inappropriately (i.e., shaking soiled linens). Bacteria (Salmonella spp., Bacillus cereus), viruses (hepatitis B virus), fungi (Microsporum canis), and ectoparasites (scabies) presumably have been transmitted from soiled textiles and fabrics to workers via either direct contact or aerosols consisting of contaminated lint generated from sorting and handling soiled linen.1162 – 1166

OSHA defines contaminated laundry as "laundry which has been soiled with blood or other potentially infectious materials or may contain sharps."911 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 soiled linens, fabrics, and textiles through the use of personal protective equipment, proper work practices, containment, labeling, hazard communication, and ergonomics.

The issue as to whether healthcare workers should be obligated to take work clothing home for laundering is complicated. OSHA regulation prohibit home laundering of items that are considered personal protective equipment (e.g., laboratory coats, surgical attire).911 There is disagreement, however, about whether this extends to uniforms and scrub suits which are not contaminated with blood or other potentially infectious material. Healthcare facility policies on this matter vary greatly. 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 healthcare facilities require the use of uniforms, it would seem reasonable that they provide workers with clean uniforms. Healthcare facilities should address both the need to provide this service or not and to 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.1167 The heaviest bacterial load was found on the sleeves and the pockets of these garments, and the organisms most frequently isolated were Staphylococcus aureus, diphtheroids, and Acinetobacter spp.1167 The presumption here is that the sleeves of the coat may make contact with a patient and potentially serve to transfer environmentally-stable microorganisms among patients.

The study, however, did not conduct surveillance 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.1167

Laundry services for healthcare facilities are provided either in-house or by off-site commercial laundries. The laundry facility in a healthcare 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 healthcare facilities have been published.120, 1168

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.1169 To minimize the potential for recontaminating cleaned laundry with aerosolized contaminated lint, areas receiving soiled linens should be at negative air pressure relative to the clean areas.1170 - 1172 Laundry areas should have handwashing facilities readily available to workers. Laundry workers should wear appropriate personal protective equipment (e.g., gloves, protective garments) while sorting soiled fabrics and textiles.911 Laundry equipment should be used and maintained according to the manufacturer’s instructions to prevent microbial contamination of the system.1164, 1173 Damp linens should not be left in machines overnight.1164

The laundry process starts with the removal of used or soiled textiles, fabrics, and/or clothing from the areas where such items are generated, including but not limited to patients’ rooms, surgical/operating areas, and laboratories. Handling soiled laundry with a minimum of agitation can help prevent the generation of potentially contaminated lint aerosols in patient-care areas.911, 1169 Sorting or rinsing soiled laundry at the point of generation should not be done. Soiled textiles and fabrics are placed into bags or other appropriate containment at the point of generation and securely tied or otherwise closed to prevent leakage.911 Single bags of sufficient tensile strength are adequate for containing laundry,1174 but leak-resistant containment is needed if the laundry is wet and can soak through a cloth bag. Bags containing soiled laundry must be clearly identified with labels, color-coding, or other methods so that healthcare workers may handle these items safely, regardless of whether the laundry is transported within the facility or destined for transport to an off-site laundry service.911

In the past, soiled laundry coming from isolation areas of the hospital was segregated and handled with special practices, even though few, if any, cases of healthcare-associated infection could be linked to this source.1175 Single-blinded studies have shown that laundry from isolation areas is no more heavily contaminated with microorganisms than laundry from elsewhere in the hospital.1176 Adherence to standard precautions when handling soiled laundry in isolation areas and minimizing agitation of the soiled items is considered sufficient to prevent the dispersal of potentially infectious aerosols.6

Soiled textiles and fabrics in bags can be transported by cart or chute.1168, 1172 Laundry chutes require proper design, maintenance, and use since the piston-like action of a laundry bag traveling in the chute can propel airborne microbial contaminants throughout the facility.1177 - 1179 Loose, soiled pieces of laundry should not be tossed into chutes.1180

Healthcare facilities should determine at what point in the laundry process textiles and fabrics should be sorted. Sorting laundry before washing protects both the machinery and fabrics from hard objects (e.g., needles, syringes, patients’ property) and reduces the potential for recontamination of clean linen.1181 Sorting after washing minimizes the exposure of laundry workers to infective material in soiled fabrics and reduces airborne microbial contamination in the laundry area.1182 Protective apparel for the workers and appropriate ventilation can minimize these exposures.911, 1168 – 1170

Gloves used for the task of sorting laundry should be of sufficient thickness to minimize sharps injuries.911 Employee safety personnel or industrial hygienists can help to determine the appropriate glove choice.

Fabrics, textiles, and clothing used in healthcare are disinfected during laundering and generally rendered free of vegetative pathogens (hygienically clean), but they are not sterile.1183 Washing machines in healthcare facilities can be either washer/extractor units or continuous batch machines. A typical washing cycle consists of three main phases – a prewash, a main wash, and the rinse cycle. Cleaned wet textiles, fabrics, and clothing are then dried, pressed as needed, and prepared (e.g., folding and packaging) for distribution back to the facility. Clean linens provided by an off-site laundry must be wrapped prior to transport to prevent inadvertent contamination from dust and dirt during loading, delivery, and unloading. The antimicrobial action of the laundering process results from a combination of physical and chemical factors.1182, 1184, 1185 Dilution and agitation in water remove significant quantities of microorganisms. Soaps and detergents loosen soil and also have some microbicidal properties. Hot water provides an effective means of destroying microorganisms.1186 A temperature of at least 71°C (160°F) for a minimum of 25 minutes is commonly recommended for hot-water washing.2 Water of this temperature can be provided by steam jet or separate booster heater.120

Chlorine bleach provides an extra margin of safety.1187, 1188 A total available chlorine residual of 50-150 ppm is usually achieved during the bleach cycle.1186 The last action in the washing process is the addition of a mild acid to neutralize any alkalinity in the water supply, soap, or detergent. The rapid shift in pH from approximately 12 to 5 may also inactivate some microorganisms.1161

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. Bleach was not recommended in the past for laundering flame-retardant fabrics, linens, and clothing bacause its use diminished the flame-retardant properties of the treated fabric.1183 Some modern-day flame retardant fabrics can now tolerate chlorine bleach, and chlorine alternatives such as activated oxygen-based laundry detergents provide added benefits for fabric and color safety in addition to antimicrobial activity. Oxygen-based bleach and detergents used in healthcare settings should be registered by the EPA to ensure adequate disinfection of laundry. Healthcare workers should note the cleaning instructions of textiles, fabrics, drapes, and clothing to identify special laundering requirements and appropriate hygienic cleaning options.1187

Although hot-water washing is an effective laundry disinfection method, the cost can be significant. Laundries are typically the largest users of hot water in hospitals, consuming 50% - 75% of the total hot water.1189 This represents an average of 10% - 15% of the energy used by a hospital. Several studies have shown that lower water temperatures of 22°C - 50°C (71°F - 77°F) can satisfactorily reduce microbial contamination when the cycling of the washer, the wash detergent, and the amount of bleach are carefully monitored and controlled.1161, 1190 - 1194 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 healthcare facility licensing standards or 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.1161

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.2 The transport of cleaned textiles and fabrics is handled separately from transport of contaminated laundry. State regulations and/or accrediting standards may dictate the procedures for this activity.

In the absence of microbiological standards for laundered linens, there is no rationale for routine microbiological sampling of cleaned healthcare textiles and fabrics.1195 Sampling may be used as part of an outbreak investigation if epidemiologic evidence suggests textiles, fabrics, or clothing as a 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.1182, 1195 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.1196

Some fabric items (e.g., surgical drapes, reusable gowns, and scrubs) need to be sterilized before use and therefore require steam autoclaving after laundering.7 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 of infection among the neonates receiving care.1197 Consequently, hygienically clean linens are suitable for use in this setting.939 The use of sterile linens in burn therapy units remains unresolved.

Dry cleaning, a laundering process which utilizes organic solvents such as perchloroethylene for soil removal, is an alternative means of cleaning fabrics that might be damaged in conventional water and detergent washing. A number of studies, however, have shown that dry cleaning alone is relatively ineffective in reducing the numbers of bacteria and viruses on contaminated linens;1198, 1199 microbial populations are significantly reduced only when dry cleaned articles are heat pressed. Dry cleaning should therefore not be considered a routine option for healthcare facility laundry and should be reserved for those special circumstances for fabrics which cannot be safely cleaned with water and detergent.1200

An issue of recent concern is the use of disposable (single use) versus reusable (multiple use) surgical attire and fabrics in health care.1201 Regardless of the material used to manufacture gowns and drapes, these items need to be impermeable to liquids and viruses.7, 1202, 1203 Repellency and pore size of the fabric contribute to gown performance,1204 but repeated launderings of reusable gowns appeared to reduce the ability of the fabric to prevent transmission of bacteria.1205, 1206

Reinforced gowns (i.e., gowns with double-layered fabric) are generally more resistant to liquid strike-through.1207, 1208

In one study in Europe, surgeons overwhelmingly preferred reinforced disposable gowns to a reusable cotton gown based on the ability of the fabric to prevent liquid strike-through.1208 Reinforced gowns may, however, be less comfortable. Guidelines for selection and use of barrier materials for surgical gowns and drapes have been published.1209 Preferred product attributes include: 1) adequate barrier performance against liquids and microorganisms; 2) compatibility with reprocessing methods if reusable; 3) durability against tears and staining; 4) lack of toxicity; 5) low lint production; and 6) a positive cost-benefit ratio. It is the responsibility of the healthcare facility to assure optimal protection of patients and healthcare workers. Not all fabric items in healthcare 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, the staff expenses to collect, sort, clean, and package the laundry, and the energy costs to operate the laundry if on-site or the costs to contract with an outside service.1210

In the healthcare setting, treated items include children’s pajamas, mattresses, and bed linens with label claims of antimicrobial properties. These claims require careful evaluation to determine if they pertain to the use of antimicrobial chemicals as preservatives for the fabric or other components or if they imply a health claim.1211 At present there is no evidence that use of these products will make consumers and patients healthier or prevent disease. There are no data to support the use of these items as part of a sound infection control strategy, and therefore there is little evidence to justify the additional expense expected if a facility were to replace its bedding and sheets with these treated products.

The 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.1212 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.1213

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. 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 significant environmental source of microorganisms. Infections and colonizations due to Acinetobacter spp., methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa have been described, especially among burn patients.1214 - 1219 In

these reports, the removal of wet mattresses was an important infection control measure, and efforts were made to ensure that pads and covers were cleaned and disinfected between patients, using disinfectant products compatible with mattress-cover materials so that these covers remained impermeable to fluids.1214 - 1218 Pillows and their covers should be easily cleanable, preferably in a hot water laundry cycle.1219

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, burns).1220 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. Pathogens such as Enterococcus spp., Serratia marcescens, Staphylococcus aureus, and Streptococcus fecalis have been recovered either from the microsphere beads or the polyester sheet after cleaning.1221, 1222 Reports of cross-contamination of patients, however, are few.1222 Nevertheless, routine maintenance and between-patient decontamination procedures are important to 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.1223 - 1225

Beads are decontaminated in between patients by high heat (range 45°C - 90°C [113°F - 194°F], depending on the manufacturer’s specifications) for at least 1 hour; this is especially important for the inactivation of Enterococcus spp. which are relatively resistant to heat.1226, 1227 The polyester filter sheet requires regular changing and thorough cleaning and disinfection, especially between patients.1221, 1222, 1226,1227

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, even though air flows out of the base unit and around the patient.1224, 1228, 1229 An operational air-fluidized bed may, however, interfere with proper pressure differentials, especially in negative-pressure rooms.1230 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.

Although dogs and cats are commonly encountered in healthcare settings, other animals (e.g., fish, birds, non-human primates, rabbits, rodents, reptiles) can also be present as research, resident, or service animals. These animals can serve as sources of zoonotic pathogens that could potentially infect patients and healthcare workers (Table 39).1231 - 1244 There is the potential for animals to serve as reservoirs for antibiotic-resistant microorganisms which could be introduced to the healthcare setting while the animal is present. Vancomycin-resistant enterococci (VRE) have been isolated from both farm animals and pets,1245 and a cat in a geriatric care center was found to be colonized with methicillin-resistant Staphylococcus aureus (MRSA).1246

Table 39. Examples of Diseases Associated with Zoonotic Transmission a

a. Adapted from Reference 1235 and used with permission of the publisher. This table does not include vectorborne diseases.

b. Reptiles include lizards, snakes, and turtles. Rodents include hamsters, mice, and rats.

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