The Role of Environmental Cleaning in Infection Control
By Jamie Wolf
Articles documenting infection after improper reprocessing of patient-care items and decontamination of surfaces have emphasized the need for appropriate cleaning and disinfection. Although most nosocomial infections result from patients' endogenous flora or person-to-person transmission, contaminated surfaces also have been linked to nosocomial infection.1 When it comes to environmental cleaning in healthcare settings, there are a wide range of products and procedures used. To implement evidence-based practices, it is important to have current information and background knowledge about the role of the environment in infection control.
The Contaminated Environment
Environmental surfaces may become contaminated with human pathogens, and extensive environmental contamination has been demonstrated in rooms of patients with methicillin-resistant Staphylococcus aureus, 2, 3 vancomycin-resistant Enterococcus (VRE) 4 and C. difficele. 5 Environmental surfaces also can be contaminated with bloodborne pathogens, respiratory and enteric viruses, and other harmful microorganisms. There is little evidence that housekeeping surfaces such as floors and walls are a direct source of infection for patients. 6
However, exposure to contaminated patient-care items such as rectal thermometers, commodes, and high-touch surfaces, have been implicated as a source of infection. 5 The transfer of microorganisms from the environment occurs through hand contact with these surfaces. Although the efficiency of direct transmission of microorganisms from surfaces has not been defined in well-controlled studies, there is adequate evidence to support the need for implementing good procedures for cleaning and disinfection of high-touch surfaces. The level of disinfection and the type of cleaning agent required depends on factors such as: the surface classification, resistance of the 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 equipment according 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 equipment and surfaces to more clearly define the risk of disease transmission from contact with these surfaces. 7 Environmental surfaces are defined as housekeeping surfaces such as: floors, walls, beds, bed rails, bedside tables, and medical equipment surfaces such as: frequently touched adjustment knobs on x-ray machines, monitors, and instrument carts.
Along with the categorization of medical equipment, Spaulding also proposed three levels of disinfection: high level, intermediate level, and low level. 8,9 The basis for these levels is that microorganisms can be grouped according to their innate resistance to physical or germicidal agents.
High-level destroys all microorganisms, with the exception of high numbers of bacterial spores.
Intermediate level inactivates mycobacterium tuberculosis, vegetative bacteria, fungi, and lipid and nonlipid viruses. It does not kill resistant bacterial spores. It is equivalent to an EPA-registered, hospital-grade disinfectant effective against mycobacterium, such as a phenolic or chlorine.
Low-level kills most vegetative bacteria, fungi, and lipid viruses, including hepatitis B and HIV. It will not kill resistant spores or nonlipid viruses. It is equivalent to a hospital-grade disinfectant that is not EPA-registered as effective against mycobacterium, such as a quat.
Principles of Environmental Cleaning
Bedrails are an example of high-touch surfaces and should be cleaned more frequently than surfaces with minimal hand contact.
Although disinfectant-detergent formulations registered by the EPA are used for environmental surface cleaning, 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. 10
The activity of disinfectants against microorganisms depends on both the intrinsic qualities of the organisms (some are more innately resistant) while others depend on the chemical and physical environment. Key factors influencing the 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.
- 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 disinfecting environmental 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 levels can be achieved by keeping the surfaces visibly clean using water and a detergent or a low-level disinfectant. For medical equipment surfaces heavily contaminated with microorganisms such as bedpans and urine-measurement containers, cleaning which is then followed by application of a low or intermediate-level disinfectant may be appropriate. Housekeeping surfaces can be divided into two groups--those with high-hand contact (bedrails, beds, overbed tables) and those with minimal hand-contact (floors and walls). High-touch surfaces should be cleaned/or disinfected more frequently than surfaces with minimal 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 care areas housing patients at greatest risk of infection, such as: ICU, oncology, dialysis, and surgery. Physical removal of microorganisms and soil by scrubbing is more important than the antimicrobial effect of the cleaning solution. Therefore, the acceptance by cleaning personnel, safety, and cost are the main criteria for selecting cleaning solutions.
Myths and Misperceptions
Common misperceptions often abound when choosing the proper disinfectant for the job. Some practitioners believe that using a phenolic or chlorine is the only way to comply with the OSHA bloodborne pathogens standard. However, a facility also can comply with OSHA by using a quat disinfectant with an HIV/HBV label claim. Studies have shown that hepatitis B and HIV are inactivated by quaternary ammonium compounds.12, 13 Cleaning with a quat is cost effective and allows for a streamlined cleaning process.
Although it is important--both aesthetically and to reduce the microbial load to a safe level--to regularly clean housekeeping surfaces such as floors and walls, these surfaces have not been directly linked to nosocomial infections. Maintaining these surfaces in a state of visible cleanliness, using a general purpose or neutral cleaner, will provide an adequate level of safety.
Environmental cleaning is an important part of breaking the chain of infection. There are a variety of disinfectants available to combat infectious microorganisms. Infection control professionals (ICPs) and patient-care staff should work together to identify the high-touch surfaces and then determine the appropriate chemical germicide, cleaning method, and schedule. Nosocomial infections 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 Care Division in St. Paul, Minn.
For a complete list of references click here