General Guidelines for Use of Chemical Disinfectants

Disinfection of Bloodborne Pathogens

Paula Grahs RN, BSN, CNOR

For the disinfection of bloodborne pathogens knowledge of the basic principles of disinfection is needed to prevent the risk of disease transmission via inanimate objects. It is the responsibility of all personnel involved with handling these objects to understand these principles. Studies have shown that bloodborne pathogens (HIV, HBV, and HCV) are inactivated rapidly after being exposed to commonly-used chemical disinfectants at concentrations that are much lower than those used in practice.^4,7

Disinfection is the process that eliminates many or all pathogenic microorganisms with the exception of bacterial spores from inanimate objects.² Disinfection is affected by a number of factors:

• Proper cleaning of the object. Disinfection cannot take place without proper cleaning. This is the most important step in the process.¹
• Organic load (blood, mucous, tissue, and feces) on the object may bind up the active ingredients of the disinfectant and possibly reduce disinfectant activity.
• Type and level of microbial contamination. Some microorganisms are more resistant to aqueous disinfectants than others (Table 1). The level of microorganisms is also important, if there is a heavy load of microorganisms; the disinfectant chosen must be able to handle the load.
• Concentration, exposure time, and temperature of the disinfectant vary with each product--follow manufacturer recommendations.
• Physical makeup of the object (crevices, hinges, and lumens). The disinfectant must be able to contact all areas of the object.
• pH of the disinfection process. Different products are formulated to be more effective over a range of pH values. Some work better in an alkaline pH and some are more effective in an acetic or acid condition.
• Hardness of water. Minerals such as calcium and magnesium can also affect the efficacy of the disinfectant by tying up the active ingredients. Be sure to check with the manufacturer if using with hard water conditions.⁶
• In 1985, the CDC's Guideline for Handwashing and Hospital Environmental Control defined the levels of disinfection, sterilization, high-level disinfection, intermediate-level disinfection, and low-level disinfection.
• Sterilization is the destruction of all microorganisms, including bacterial spores. High-level disinfection is expected to destroy all microorganisms with the exception of bacterial spores. The Food and Drug Administration (FDA) clears these chemical germicides.²
• Intermediate-level disinfection inactivates Mycobacterium tuberculosis, vegetative bacteria, most viruses and most fungi, but it does not necessarily kill bacterial spores. These chemical germicides are registered as a "tuberculocide" by the Environmental Protection Agency (EPA).²
• Low-level disinfection inactivates vegetative bacteria, most viruses and most fungi, but it cannot be relied upon to kill resistant microorganisms such as tubercle bacilli or bacterial spores. Efficacy against TB on hard surfaces is irrevelant, however, since TB is an aerosolized organism and disinfectants are used on surfaces. The EPA registers these chemical germicides as a hospital disinfectant.²
• A rational approach to disinfection was devised by Dr. E. H. Spaulding. This classification system is still applicable for use today to plan for disinfection or sterilization. Spaulding believed that the nature of disinfection could be understood more readily if instruments and items for patient care were divided into three categories according to the degree of risk of infection associated with the use of the item. These three categories are critical, semicritical, and noncritical.²
• Critical items present a high risk of infection if contaminated with any microorganisms including bacterial spores. It is critical that objects entering sterile tissue or the vascular system be kept sterile.
• Semi-critical items are those objects that come in contact with mucous membranes or skin that is not intact. These items must be free of all microorganisms with the exception of high numbers of bacterial spores.
• Noncritical items come in contact with intact skin but not with mucous membranes. Intact skin acts as an effective barrier to most microorganisms.²

Table 2 correlates the three device classifications with Spaulding's process classifications and the EPA's product classification.

General Guidelines for Use of Chemical Disinfectants

Universal Precautions with the appropriate personnel protective equipment should always be used when dealing with contaminated items during cleaning and decontamination procedures. Items must be thoroughly cleaned before being disinfected because dirt, blood, mucous, and tissue may interfere with the action of the disinfectant.

The disinfectant in sufficient concentrations at the correct temperature must remain in contact with the surfaces for a specific period of time to allow penetration of all the microbial cell walls and deactivation. The concentration, temperature, and exposure times are different for each disinfectant and the manufacturer's directions for use must be followed carefully.

Chemical disinfectants should not be mixed with each other or with detergents, since this may inactivate their disinfecting properties or create noxious fumes.

If air is entrapped under or within an item, the disinfectant cannot completely contact all the surfaces. Items should be dry to prevent dilution of the disinfectant. When indicated, it is essential that the disinfectant be thoroughly rinsed from items before the items are used. Be sure that you always follow the manufacturer's recommendations when using chemical disinfectants.

Personnel should take precautions to avoid direct contact with chemical disinfectants and they should always be used in well-ventilated areas. Material Safety Data Sheets (MSDS) should be readily available in the event of exposure.

Disinfection of Devices Contaminated with Bloodborne Pathogens ⁵

Some ask if we should sterilize or high-level disinfect semi-critical medical devices contaminated by blood from patients infected with a bloodborne disease. The CDC recommendation for high level disinfection is appropriate because studies have shown the effectiveness of high level disinfectants to inactivate these and other pathogens that may contaminate semi-critical devices.² To sterilize these items when used on certain infectious patients may lead to a "double standard" of patient care and is inconsistent with the principles of universal precautions when equipment used on patients with known specific infectious diseases is sterilized, but the same equipment is high-level disinfected for other patients. Sterilization should not be performed in the belief that it is providing a greater margin of safety. Standard sterilization and disinfection procedures for patient care equipment are adequate to sterilize or disinfect instruments or devices contaminated with blood or other body fluids from persons infected with bloodborne pathogens. No changes in procedures for cleaning, disinfecting, or sterilizing need to be made.²

Chemical germicides that are EPA approved for use as "hospital disinfectants" and that are tuberculocidal/virucidal or have HIV/human HBV claims (OSHA, 1997, 1999) when used at recommended dilutions and contact times can be used to decontaminate spills of blood. Extraordinary attempts to disinfect walls and floors or other environmental surfaces are not necessary. However, cleaning and removal of soil should be done on a routine basis.^4,7

The importance of proper cleaning and disinfection cannot be stressed enough and it is essential in protecting patients and personnel from potentially harmful microorganisms. When considering disinfection of bloodborne pathogens, the basic principles of disinfection apply. Careful attention to the process of cleaning and disinfection will provide the safety that is needed when an item is being reused in caring for patients.

Paula Grahs, RN, BSN, CNOR is Central Supply Manager at St. Luke's Hospital in Cedar Rapids, Iowa.

Rutala WA. "APIC Guidelines for Selection and Use of Disinfectants. American Journal of Infection Control 1996; 24:315. OSHA, 1997, 1999.

REFERENCES
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Table 1: Microbial resistance to disintectants

BACTERIAL SPORES
Bacillus subtilis

MYCOBACTERIA
Mycobacterium tuberculosis

NONLIPID OR SMALL VIRUSES
Polio virus

FUNGI
Trichophyton spp.

VEGETATIVE BACTERIA
Pseudomonas aeruginosa
Staphylococcus aureus

LIPID OR MEDIUM-SIZED VIRUSES
Herpes simplex virus
Human immunodeficiency virus

Descending order of resistance to germicidal chemicals. This hierarchy considers broad classifications of microbial categories. It is considered a rough guide to general susceptibility of microorganisms to disinfectants.

Rutala WA. APIC Guidelines for Selection and Use of Disinfectants. American Journal of Infection Control 1996; 24: 314.

Table 2: Classification of devices, processes, and germicidal products

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