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Principles of disinfection: Part 2
PRINCIPLES OF DISINFECTION: PART2 Robert
J. Sharbaugh,
PhD,
CIC
This article is the second of two parts devoted to a brief description of eliminating pathogenic microorganisms, with the exception of bacterial spores, from inanimate patient care items using liquid disinfectants. Part 1 (Home Care Provider, February 1998, pages 17- 19) offered a review of current chemical disinfectants and their advantages and disadvantages. In this part, the discussion will center on disinfectant efficacy and recommendations for clinical disinfection of patient care items based on their intended use. As part t discussed, liquid disinfectants are placed into one of three categories based on their level of germicidal action: l
l
l
High-level disinfectants are capable of destroying all microorganisms with the exception of microbial spores. Intermediate-level disinfectants will destroy vegetative bacteria, most viruses and fungi, and Mycobacteriumtuberculosis but not microbial spores. Low-level disinfectants will kill most bacteria and some viruses and fungi but neither M. tuberculosisnor bacterial spores.
Many environmental and chemical factors have direct bearing on the efficacy of any disinfection process, including temperature, pH, and water hardness. In general, an increase in temperature usually hastens any disinfection, and higher concentrations of active ingredients tend to increase the bactericidal ability of any disinfectant. The relative acidity or alkalinity (pH) also can influence the
APRIL 1998, VOL.
3
NO.
2
biocidal activity of most disinfectants. For best results and safety, products should be used according to the manufacturer’s recommendations. Failure to follow the manufacturer’s instructions may generate potential health hazards for employees and degrade the product. A direct relationship exists between the number and type of microbes present and the comparative ease of disinfection. As a result, meticulously cleaning patient care items before using any disinfectant is of paramount importance. Reducing the number of organisms also reduces the amount of time necessary to kill any that remain. The efficacy of any disinfectant also depends on direct contact with the organism. Disassembling instruments may be necessary to allow the disinfectant to penetrate all parts of the product. The presence of organic material, such as blood, pus, and feces, not only prevents direct contact with the microorganisms but also helps inactivate most disinfectants, with the exception of glutaraldehyde. Chlorine and the iodophors are particularly prone to such inactivation. Again, the importance of meticulous cleaning with a detergent before any disinfection procedure cannot be overstated. Many factors inherent to liquid disinfectants greatly influence the time necessary to achieve disinfection. For all high-level disinfectants, a minimum contact time of 20 to 30 minutes is recommended. Intermediate- and low-level
HOME
CARE PROVIDER
79
SHORT TOPICS IN INFECTION CONTROL disinfection generally can be achieved in 5 to IO minutes. Just as disinfectants are classified on three levels, patient care items routinely are classified as either critical, semicritical, or noncritical based on the risk of infection associated with their use. Understanding the relationship between levels of disinfection and the intended use of a patient care item is important. Critical items bear a high risk of infection if they are contaminated when in use. Thus any product intended for use in the bloodstream or other sterile area of the body must be sterile. In the home care arena, this category includes needles, vascular or urinary catheters, and infusion solutions. Semicritical items are products that will enter neither the bloodstream nor other sterile areas but will come into contact with mucous membranes or nonintact skin. Preferably, such items should be sterile. However, highlevel disinfection is an accepted standard of care for semicritical items when sterilization is not possible. Semicritical items include some respiratory therapy equipment and endotracheal tubes. A few items, by definition, are classified as semicritical but can be safely processed using an intermediate-level disinfectant (e.g., thermometers). Noncritical items are limited to contact with intact skin and rarely, if ever, necessitate sterility or high- or intermediate-level disinfection. Rather, cleaning with a simple detergent when visibly soiled, followed by low-level disinfection is the accepted standard of care for items in this category. Examples of such items commonly used in home care include bedpans, patient furniture, scales, crutches, and blood pressure cuffs.
Sharing in All Dimensions women at low risk not be screened, including women who satisfy all these criteria: younger than 25, normal body weight, no family history of diabetes, and not a member of an ethnic group with a high prevalence of diabetes. Home health nurses may benefit their postpartum patients by reinforcing healthy lifestyles because 50% of women with gestational diabetes go on to develop type 2 diabetes. Gavin says he thinks these recommendations will have a major impact on American public health. “Adults in America, especially family members of people with diabetes and other high-risk individuals, should be more vigilant in getting checked for this disease on a regular basis and should try to reduce their risk by maintaining ideal weight and seeking to control blood pressure and blood fat levels,” he says. “These recommendations are meant to urge providers to be ‘thinking diabetes’ when routinely assessingthe health and well-being of all patients age 45 or older, especially those with risk factors for the disease,”Beebe summarizes. “Home care nurses are in an ideal position for early diseasescreening, patient and family teaching, and treatment monitoring.” Gavin concludes, “Only then can we have hope of stopping the ever-upward spiral of blindness, kidney failure, amputations, heart disease, and stroke caused by this insidious disease.”
Health care workers often are faced with the dilemma of deciding which process to use to disinfect patient care items. Carefully considering the relationship between disinfectant efficacy and the intended use of the product usually serves well to answer such questions.
80 HOME
CARE PROVIDER
APRIL 1998, VOL. 3 NO. 2
J. Sharbaugh,
PhD,
CIC
This article is the second of two parts devoted to a brief description of eliminating pathogenic microorganisms, with the exception of bacterial spores, from inanimate patient care items using liquid disinfectants. Part 1 (Home Care Provider, February 1998, pages 17- 19) offered a review of current chemical disinfectants and their advantages and disadvantages. In this part, the discussion will center on disinfectant efficacy and recommendations for clinical disinfection of patient care items based on their intended use. As part t discussed, liquid disinfectants are placed into one of three categories based on their level of germicidal action: l
l
l
High-level disinfectants are capable of destroying all microorganisms with the exception of microbial spores. Intermediate-level disinfectants will destroy vegetative bacteria, most viruses and fungi, and Mycobacteriumtuberculosis but not microbial spores. Low-level disinfectants will kill most bacteria and some viruses and fungi but neither M. tuberculosisnor bacterial spores.
Many environmental and chemical factors have direct bearing on the efficacy of any disinfection process, including temperature, pH, and water hardness. In general, an increase in temperature usually hastens any disinfection, and higher concentrations of active ingredients tend to increase the bactericidal ability of any disinfectant. The relative acidity or alkalinity (pH) also can influence the
APRIL 1998, VOL.
3
NO.
2
biocidal activity of most disinfectants. For best results and safety, products should be used according to the manufacturer’s recommendations. Failure to follow the manufacturer’s instructions may generate potential health hazards for employees and degrade the product. A direct relationship exists between the number and type of microbes present and the comparative ease of disinfection. As a result, meticulously cleaning patient care items before using any disinfectant is of paramount importance. Reducing the number of organisms also reduces the amount of time necessary to kill any that remain. The efficacy of any disinfectant also depends on direct contact with the organism. Disassembling instruments may be necessary to allow the disinfectant to penetrate all parts of the product. The presence of organic material, such as blood, pus, and feces, not only prevents direct contact with the microorganisms but also helps inactivate most disinfectants, with the exception of glutaraldehyde. Chlorine and the iodophors are particularly prone to such inactivation. Again, the importance of meticulous cleaning with a detergent before any disinfection procedure cannot be overstated. Many factors inherent to liquid disinfectants greatly influence the time necessary to achieve disinfection. For all high-level disinfectants, a minimum contact time of 20 to 30 minutes is recommended. Intermediate- and low-level
HOME
CARE PROVIDER
79
SHORT TOPICS IN INFECTION CONTROL disinfection generally can be achieved in 5 to IO minutes. Just as disinfectants are classified on three levels, patient care items routinely are classified as either critical, semicritical, or noncritical based on the risk of infection associated with their use. Understanding the relationship between levels of disinfection and the intended use of a patient care item is important. Critical items bear a high risk of infection if they are contaminated when in use. Thus any product intended for use in the bloodstream or other sterile area of the body must be sterile. In the home care arena, this category includes needles, vascular or urinary catheters, and infusion solutions. Semicritical items are products that will enter neither the bloodstream nor other sterile areas but will come into contact with mucous membranes or nonintact skin. Preferably, such items should be sterile. However, highlevel disinfection is an accepted standard of care for semicritical items when sterilization is not possible. Semicritical items include some respiratory therapy equipment and endotracheal tubes. A few items, by definition, are classified as semicritical but can be safely processed using an intermediate-level disinfectant (e.g., thermometers). Noncritical items are limited to contact with intact skin and rarely, if ever, necessitate sterility or high- or intermediate-level disinfection. Rather, cleaning with a simple detergent when visibly soiled, followed by low-level disinfection is the accepted standard of care for items in this category. Examples of such items commonly used in home care include bedpans, patient furniture, scales, crutches, and blood pressure cuffs.
Sharing in All Dimensions women at low risk not be screened, including women who satisfy all these criteria: younger than 25, normal body weight, no family history of diabetes, and not a member of an ethnic group with a high prevalence of diabetes. Home health nurses may benefit their postpartum patients by reinforcing healthy lifestyles because 50% of women with gestational diabetes go on to develop type 2 diabetes. Gavin says he thinks these recommendations will have a major impact on American public health. “Adults in America, especially family members of people with diabetes and other high-risk individuals, should be more vigilant in getting checked for this disease on a regular basis and should try to reduce their risk by maintaining ideal weight and seeking to control blood pressure and blood fat levels,” he says. “These recommendations are meant to urge providers to be ‘thinking diabetes’ when routinely assessingthe health and well-being of all patients age 45 or older, especially those with risk factors for the disease,”Beebe summarizes. “Home care nurses are in an ideal position for early diseasescreening, patient and family teaching, and treatment monitoring.” Gavin concludes, “Only then can we have hope of stopping the ever-upward spiral of blindness, kidney failure, amputations, heart disease, and stroke caused by this insidious disease.”
Health care workers often are faced with the dilemma of deciding which process to use to disinfect patient care items. Carefully considering the relationship between disinfectant efficacy and the intended use of the product usually serves well to answer such questions.
80 HOME
CARE PROVIDER
APRIL 1998, VOL. 3 NO. 2