Infection Control Today - 04/2001: The Role of Environmental Cleaning inInfection Control

The Role of Environmental Cleaning in Infection Control

By Jamie Wolf

Articles documenting infection after improper reprocessing of patient-careitems and decontamination of surfaces have emphasized the need for appropriatecleaning and disinfection. Although most nosocomial infections result frompatients' endogenous flora or person-to-person transmission, contaminatedsurfaces also have been linked to nosocomial infection.1 When itcomes to environmental cleaning in healthcare settings, there are a wide rangeof products and procedures used. To implement evidence-based practices, it isimportant to have current information and background knowledge about the role ofthe environment in infection control.

The Contaminated Environment

Environmental surfaces may become contaminated with human pathogens, andextensive environmental contamination has been demonstrated in rooms of patientswith methicillin-resistant Staphylococcus aureus, 2, 3vancomycin-resistant Enterococcus (VRE) 4 and C. difficele.5 Environmental surfaces also can be contaminated with bloodbornepathogens, respiratory and enteric viruses, and other harmful microorganisms.There is little evidence that housekeeping surfaces such as floors and walls area direct source of infection for patients. 6

However, exposure to contaminated patient-care items such as rectalthermometers, commodes, and high-touch surfaces, have been implicated as asource of infection. 5 The transfer of microorganisms from theenvironment occurs through hand contact with these surfaces. Although theefficiency of direct transmission of microorganisms from surfaces has not beendefined in well-controlled studies, there is adequate evidence to support theneed for implementing good procedures for cleaning and disinfection ofhigh-touch surfaces. The level of disinfection and the type of cleaning agentrequired depends on factors such as: the surface classification, resistance ofthe microorganism to the chemical germicide, cost, safety, and ease of use.

In the 1970s, E.H. Spaulding developed a system to classify the cleaning,disinfection, and sterilization requirements for patient-care equipmentaccording to the risk of infection. The categories are as follows:

  • Critical items, such as surgical instruments, enter sterile tissue. The risk of infection is substantial and sterilization by steam, ethylene oxide (ETO), or other methods is necessary.

  • Semi-critical items, such as endoscopes, come into contact with mucous membranes and the risk of infection is significant. These items must undergo high-level disinfection with a chemical disinfectant, such as glutaraldehyde.

  • Non-critical items come into contact with intact skin only, and the infection risk is very low. This includes housekeeping surfaces, including floors, walls, tabletops, and medical equipment surfaces such as blood pressure cuffs, commodes, and adjustment knobs. These items can be made safe for patient and staff contact by good cleaning with a low-level disinfectant, such as a quaternary ammonium compound (quat).

In the 1990s, the US Centers for Disease Control and Prevention (CDC)expanded Spaulding's original classification of non-critical medical equipmentand surfaces to more clearly define the risk of disease transmission fromcontact with these surfaces. 7 Environmental surfaces are defined ashousekeeping surfaces such as: floors, walls, beds, bed rails, bedside tables,and medical equipment surfaces such as: frequently touched adjustment knobs onx-ray machines, monitors, and instrument carts.

Along with the categorization of medical equipment, Spaulding also proposedthree levels of disinfection: high level, intermediate level, and low level. 8,9The basis for these levels is that microorganisms can be grouped according totheir innate resistance to physical or germicidal agents.

High-level destroys all microorganisms, with the exception of high numbers ofbacterial spores.

Intermediate level inactivates mycobacterium tuberculosis, vegetativebacteria, fungi, and lipid and nonlipid viruses. It does not kill resistantbacterial spores. It is equivalent to an EPA-registered, hospital-gradedisinfectant effective against mycobacterium, such as a phenolic or chlorine.

Low-level kills most vegetative bacteria, fungi, and lipid viruses, includinghepatitis B and HIV. It will not kill resistant spores or nonlipid viruses. Itis equivalent to a hospital-grade disinfectant that is not EPA-registered aseffective against mycobacterium, such as a quat.

Principles of Environmental Cleaning

Although disinfectant-detergent formulations registered by the EPA are usedfor environmental surface cleaning, the actual physical removal ofmicroorganisms and soil by scrubbing is probably as important, if not more so,than any antimicrobial effect of the cleaning agent used. 10

The activity of disinfectants against microorganisms depends on both theintrinsic qualities of the organisms (some are more innately resistant) whileothers depend on the chemical and physical environment. Key factors influencingthe effectiveness of cleaning and disinfection are:11

  • Concentration of disinfectant: The more concentrated the germicide, the greater its killing capacity. Higher concentrations, however, are more likely to damage surfaces. If the concentration is too low, the killing capacity is reduced.

  • Number and location of microorganisms: The greater the number of organisms, the longer it takes for them to be destroyed by a germicide. How easily the organisms can be reached also is a factor. Horizontal surfaces have higher numbers of organisms than vertical surfaces, ceilings, and walls.

  • Resistance of microorganisms to the germicide: Some organisms are intrinsically resistant to certain chemicals. The most resistant forms of microorganisms are spores; mycobacteria are also very resistant. Fortunately, HIV and hepatitis B are destroyed by low-level disinfectants.

  • Contact time: To do its job, a germicide must have direct contact with the surfaces to be disinfected. Duration of exposure for adequate disinfection is related to the efficacy of the germicide and efficiency of the process.

  • Physical and chemical factors: Temperature, pH, and water hardness affect the activity of most disinfectants.

Cleaning Methods

  • Quaternary ammonium compounds (quats) are low-level disinfectants used in the cleaning and disinfecting of housekeeping surfaces and some non-critical medical equipment. Some quats meet OSHA's bloodborne pathogen standard. Quats are good cleaning agents with a wide range of effectiveness. They have a pH closer to neutral than other disinfectants, are low cost, and have a reasonable shelf life. Drawbacks to using quats include their tendency to become inactivated by organic matter, and they are neutralized and absorbed by materials and fibers. Soap and hard water may limit quats' effectiveness, and they are not sporicidal or tuberculocidal. Each quat product will have different hard water tolerance, soil load, shelf life, and kill-claim capabilities.

  • Phenolics are intermediate-level disinfectants used in the decontamination of laboratory surfaces and non-critical medical equipment. If tuberculocidal, phenolics meet the OSHA requirements for the clean-up of blood spills. They have a broad spectrum of antimicrobial activity and leave a film residual which expands the disinfection time. Phenolics are known to leave a film and build-up on surfaces that may irritate the skin and should be removed periodically. Phenolics are not recommended for the cleaning of incubators and other nursery surfaces unless properly diluted, rinsed with water, and used with good ventilation. 14 They are not sporicidal and are corrosive to rubber and certain plastics.

  • Household bleach (chlorine) is another intermediate-level disinfectant used for laboratory surfaces and spot-disinfection of countertops. Chlorine also can be used for decontaminating blood spills. It has a broad spectrum of antimicrobial activity and leaves no residue. Chlorine is inexpensive, fast-acting, and meets OSHA requirements for the clean-up of blood spills. On the downside, chlorine is corrosive to metals, is volatile, light sensitive, odorous, and is not considered to be a good cleaner. Chlorine is inactivated by organic matter and has no residual activity. It may dry and irritate skin, and evaporation may alter concentration and diminish activity.

To determine the appropriate procedures for cleaning and disinfectingenvironmental surfaces, one should consider the following:

  • The potential for direct patient contact

  • The likelihood that the surface is contaminated with body substances

  • The degree and frequency of hand contact, and

  • The patient risk of infection (immuno-compromised)

For most housekeeping and medical equipment surfaces, adequate safety levelscan be achieved by keeping the surfaces visibly clean using water and adetergent or a low-level disinfectant. For medical equipment surfaces heavilycontaminated with microorganisms such as bedpans and urine-measurementcontainers, cleaning which is then followed by application of a low orintermediate-level disinfectant may be appropriate. Housekeeping surfaces can bedivided into two groups--those with high-hand contact (bedrails, beds, overbedtables) and those with minimal hand-contact (floors and walls). High-touchsurfaces should be cleaned/or disinfected more frequently than surfaces withminimal hand-contact. 6

Cleaning frequency and methods vary according to the area of the hospital.Emphasis should be placed on the high-hand contact surfaces and patient careareas housing patients at greatest risk of infection, such as: ICU, oncology,dialysis, and surgery. Physical removal of microorganisms and soil by scrubbingis more important than the antimicrobial effect of the cleaning solution.Therefore, the acceptance by cleaning personnel, safety, and cost are the maincriteria for selecting cleaning solutions.

Myths and Misperceptions

Common misperceptions often abound when choosing the proper disinfectant forthe job. Some practitioners believe that using a phenolic or chlorine is theonly way to comply with the OSHA bloodborne pathogens standard. However, afacility also can comply with OSHA by using a quat disinfectant with an HIV/HBVlabel claim. Studies have shown that hepatitis B and HIV are inactivated byquaternary ammonium compounds.12, 13 Cleaning with a quat is costeffective and allows for a streamlined cleaning process.

Although it is important--both aesthetically and to reduce the microbial loadto a safe level--to regularly clean housekeeping surfaces such as floors andwalls, these surfaces have not been directly linked to nosocomial infections.Maintaining these surfaces in a state of visible cleanliness, using a generalpurpose or neutral cleaner, will provide an adequate level of safety.

Environmental cleaning is an important part of breaking the chain ofinfection. There are a variety of disinfectants available to combat infectiousmicroorganisms. Infection control professionals (ICPs) and patient-care staffshould work together to identify the high-touch surfaces and then determine theappropriate chemical germicide, cleaning method, and schedule. Nosocomialinfections can cause significant morbidity, lengthen a patient's hospital stay,and increase the cost of healthcare. By maintaining a clean environment,healthcare facilities can reduce the risk of cross-contamination and infection.

Jamie Wolf is the healthcare marketing manager for the 3M Commercial CareDivision in St. Paul, Minn.

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