Basics of Cleaning, Disinfection and Sterilization of Instruments
The following article was originally published in Preventing Infection in Ambulatory Care, the quarterly e-publication from the Association for Professionals in Infection Control and Epidemiology (APIC). To learn more about receiving this resource and joining APIC, visit www.apic.org/ambulatorynewsletter. To learn more about APIC, visit www.apic.org.
Every instrument must be thoroughly cleaned and dried before it is further processed using a disinfection or sterilization process. Anyone who is processing instruments for patient care must understand which processes should be performed and how to properly perform them to eliminate errors that can lead to poor patient outcomes. Updated policies and procedures, based on the references in this article, should be in place as the basis for training and competency testing. This is another step you can take in "Targeting Zero Healthcare-Associated Infections (HAIs)."
Let's start with some definitions related to cleaning, disinfection and sterilization.
Cleaning: "Removal of contamination from an item to the extent necessary for further processing or for the intended use."
NOTE: In healthcare facilities, cleaning consists of the removal, usually with detergent and water, of adherent soil (e.g., blood, protein substances, and other debris) from the surfaces, crevices, serrations, joints, and lumens of instruments, devices, and equipment by a manual or mechanical process that prepares the items for safe handling and/or further decontamination.(1)
Decontamination: According to OSHA, "the use of physical or chemical means to remove, inactivate, or destroy bloodborne pathogens on a surface or item to the point where they are no longer capable of transmitting infectious particles and the surface or item is rendered safe for handling, use, or disposal."[29 CFR 1910.1030](1) Disinfection: Process that kills pathogenic and other microorganisms by physical or chemical means.
NOTE: Disinfection destroys most recognized pathogenic microorganisms but not necessarily all microbial forms, such as bacterial spores. Disinfection processes do not ensure the margin of safety associated with sterilization processes.(1)
Sterilization: Validated process used to render a product free from viable microorganisms.
NOTE: In a sterilization process, the nature of microbiological inactivation is described by an exponential function. Therefore, the presence of a viable microorganism on an individual item can be expressed in terms of probability. While this probability can be reduced to a very low number, it can never be reduced to zero.(1)
The cleaning process is the first step in producing a safe product for patient use. This can only be done if you have up-to-date use instructions from the medical device manufacturer who is responsible for ensuring that devices can be effectively cleaned, disinfected or sterilized. Instructions for use should also be available for the cleaning equipment (i.e., washer decontaminator, brushes, etc.), and cleaning agent used.
Here is a brief look at the cleaning steps:
Care and handling of contaminated reusable items at the point of use (ANSI/AAMI ST79 section 6.3)(1)
Immediate containment and transportation to the decontamination area is ideal so that the cleaning process can start as soon as possible before biofilms (accumulated biomass of bacteria and extracellular material that is tightly adhered to a surface and cannot be removed easily) start to form. If this is not possible, while wearing the appropriate personnel protective equipment (PPE) (fluid-resistant face mask, eye protection, heavy duty utility gloves and a liquid-resistant covering with long sleeves) gross soil should be removed at the point of use avoiding splashing and contamination of you or the area. A damp sponge moistened with water (not saline) can be used. If cleaning will be further delayed, such as over a weekend, use of a precleaning disinfectant is recommended.
Containment (ANSI/AAMI ST79 section 6.4)(1)
The objective is to avoid cross contamination to either people or the environment. Place contaminated instruments in a puncture-resistant, leak-proof, closable and labeled container to avoid punctures to the container or your skin. Keep the instruments moist by adding a towel moistened with water (not saline) or a foam, spray, or gel product that is designed for this use. Check with the manufacturer of the product and instruments to ensure capability.
Presoaking (ANSI/AAMI ST79 section 7.3)(1)
Your cleaning job will be easier and more efficient if the instruments are presoaked with a specialized product (e.g., an enzymatic solution). Follow the medical device manufacturer's instructions for use along with the direction for the specialized product. Thoroughly rinse after presoaking.
Disassembly (ANSI/AAMI ST79 section 7.4)(1)
In the decontamination area, unload contaminated instruments, sort, and disassemble for cleaning while wearing the appropriate PPE. Follow the medical device manufacturer's instructions for disassembly.
Cleaning (ANSI/AAMI ST79 section 7.5)(1)
Use the appropriate cleaning agent recommended by the medical device manufacturer to ensure that devices are effectively cleaned and not damaged. Follow the cleaning agent and mechanical cleaning equipment manufacturers' instructions to ensure these interdependent factors are met:
- Quality of water
- Quality, quantity, concentration and type of detergent or enzymatic cleaner
- Acceptable washing method
- Proper rinsing and drying
- Correct preparation of items to be processed by cleaning equipment
- Time and temperature parameters and load capacity of the equipment, and
- Operator performance
Remember that one cleaning process will not work for all medical devices.
Methods of cleaning (ANSI/AAMI ST79 section 184.108.40.206-220.127.116.11)(1)
Check with the medical device manufacturer to determine if a manual and/or mechanical cleaning process should be used. The type of cleaning agent should be recommended along with the appropriate size brushes and other implements that may be needed for manual cleaning. Brushes and other cleaning implements should be either single-use, disposable items, or if reusable, be decontaminated at least daily. Single-use brushes provide the advantage of always being clean (i.e. which avoids cross contamination) and of the proper shape (i.e., not deformed from multiple uses) to facilitate cleaning of internal surfaces that you cannot see. Cloths and towels should be clean, lint-free, and changed frequently. (ANSI/AAMI ST 79 section 7.5.6)(1)
In the AAMI ST79 A2:2009 amendments routine efficacy testing of mechanical cleaning equipment is recommended because of the importance of verifying the cleaning process and helping to ensure effective sterilization. "Mechanical cleaning equipment should be tested upon installation, weekly (preferably daily) during routine use, and after major repairs. A major repair is a repair that is outside the scope of routine preventive maintenance and that significantly affects the performance of the equipment. Examples include replacement of the water pump(s), detergent delivery system, heating system, water delivery system, water treatment system, or computer control or an upgrade to software."(1)
"Testing the equipment upon installation during routine use, and after repairs allows the user to verify its continued effectiveness (AORN, 2008a)"(1)
Rinsing (ANSI/AAMI ST79 section 7.5.4)(1)
Thoroughly rinse to remove loosened debris and detergents which can interfere with the disinfection and/or sterilization process. Remember that 'more is better' in this situation. Tap water can be used initially to ensure copious volumes are used, but the final rinse should be performed with treated water [e.g., deionized, distilled, or reverse osmosis (RO)] that will not contribute to staining or deterioration of instruments. Never use saline which will degrade the surface of instruments due to the salts in the solution. Regular maintenance of the water treatment process is necessary to ensure that the water does not contain pyrogens.
Verification of the cleaning process (ANSI/AAMI ST79 section 7.5.5)(1)
Visually inspect each medical device to detect any visible soil. A magnification device may be useful and lighting must be adequate to see intricate components. Device manufacturers should identify any test procedures that can be used by the healthcare facility to verify the effectiveness of the cleaning process. Annex D in ANSI/ AAMI ST79 lists some of the tests that are available for this purpose.(1)
Cleaning points to remember
- Follow the medical device, cleaning agent, mechanical cleaning equipment, brush and implement manufacturer's instructions for use
- Wear appropriate PPE
- Remove gross debris as soon as possible
- Contain and maintain instruments moist during transportation
- Start cleaning as soon as possible
- Disassemble instruments where appropriate
- Thoroughly rinse
Develop a sharps prevention program to eliminate sharp sticks. Minimize employee exposure to cleaning agents by following the manufacturer's use instructions and Material Safety Data Sheet (MSDS). The appropriate PPE and proper ventilation must be followed.
Often the question is asked whether a clean device should be further processed with a microbiocidal process, such as high-level disinfection, to decontaminate it and also render it safe for personnel to handle before it is sterilized. The new amendments from the Association for the Advancement of Medical Instrumentation (AAMI) Comprehensive guide to steam sterilization and sterility assurance in health care facilities, ANSI/AAMI ST79:2006, A1:2008 and A2:2009, address this issue. The recommended practice states:
NOTE: Refer to the device manufacturer's instructions to determine whether decontamination using microbicidal processes is required after cleaning and before terminal sterilization.(1)
Disinfection or Sterilization Process?
Sterilization of all items used in the healthcare facility would be ideal for preventing infections, but it is not feasible or economical. An alternative choice is to use disinfection. Making the decision between disinfection or sterilization depends upon the intended use of the patient care item, risk of infection and types and levels of microorganisms that need to be removed.
High-level disinfection is the primary disinfection process used for semicritical medical devices if sterilization is not possible. The Centers for Disease Control and Prevention (CDC) Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008 has a section summarizing an overview, mode of action, microbicidal activity and uses of EPA-registered or FDA-cleared disinfectants.(2) Specific recommendations for disinfection and sterilization are also avail able, and there is a specific section on high-level disinfection of endoscopes.(2)
The Association for the Advancement of Medical Instrumentation's, Chemical sterilization and high-level disinfection in health care facilities, ANSI/AAMI ST58:2005 provides information about high-level disinfection including:
- Work area design
- Personnel considerations (PPE, training, health and personal hygiene)
- Selection of liquid chemical sterilants
- Decontamination and preparation of instruments
- Using chemical sterilants safely and effectively
- Device storage and transport
- Quality control
- Quality improvement process.(3)
Ensure that the use instructions from the medical device and disinfectant manufacturers are followed so that patient safety is not compromised. The recommendation from the AAMI ST58:2005 recommended practice is to check the minimum effective concentration (MEC) of each disinfectant using an FDA-cleared test strip or chemical monitoring device "before each use."(3) This ensures that the concentration of the active ingredient is at or above the product's MEC and indicates the solution's continued effectiveness.(3)
Minimize employee exposure to disinfectants by following the manufacturer's instruction for use and Material Safety Data Sheet (MSDS). The appropriate PPE and proper ventilation must be followed. Usage of some chemicals requires an occupational exposure monitoring program.(2,3)
Sterilization of medical devices that can withstand high temperature should be done using steam sterilization because it is the most time and cost effective method available. For heat-sensitive medical devices, low temperature sterilization is used. The Centers for Disease Control and Prevention (CDC) Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008 has a section that summarizes an overview, mode of action, microbicidal activity and uses for both steam and low temperature sterilization processes.(2)
The following AAMI documents are available, and recommended, for more information about safe and proper use of specific sterilization processes:
- Low temperature chemical sterilization (i.e., hydrogen peroxide gas plasma and ozone): Chemical sterilization and high-level disinfection in health care, ANSI/AAMI ST58:2005.(3)
- Low temperature ethylene oxide sterilization: Ethylene oxide sterilization in health care facilities: Safety and effectiveness, ANSI/AAMI ST41: 2008.(4)
- Steam sterilization: Comprehensive guide to steam sterilization and sterility assurance in health care facilities, ANSI/AAMI ST79:2006, A1:2008 and A2:2009.(1)
Ensure that your healthcare facility has up-to-date medical device manufacturers' instructions for use that describe which sterilization process to use and the appropriate cycle parameters. In some cases the medical device manufacturer may require a steam sterilization process that is longer than the minimum cycle recommended by the sterilizer manufacturer. This is called an extended cycle. An example of an extended cycle is a 270ºF/132ºC dynamic-air-removal steam sterilization cycle of 10 minutes exposure time instead of four minutes, which is the minimum exposure time recommended by the sterilizer manufacturer. Always use the sterilization process and cycle recommended by the medical device manufacturers as they are responsible for validating that cycle and providing that information to you. If it is required, and you do not run an extended cycle, the medical device may not be sterile and safe for patient use.
Once the correct cycle is chosen, all of the following events must be done correctly for the process to be effective:
- Correct packaging for the sterilization process, medical device and cycle parameters
- Correct packaging procedure (e.g., peel pouches should not be placed inside instrument trays or rigid containers because they are not validated for that use and trap air)
- Packages loaded correctly in the sterilizer
- Monitoring the sterilization process with appropriate physical monitors, chemical and biological indicators
- Packages unloaded correctly from the sterilizer
- Packages cooled before handling and storage
- Proper transport and aseptic presentation of packages
Additionally, proper interpretation of the sterilization process monitors is required by the processing technicians prior to distribution and the users must also check and verify external and internal process indicators when sterilized packages are opened.
Minimize employee exposure to low temperature sterilization processes by following the manufacturer's instruction for use and the Material Safety Data Sheet (MSDS). The appropriate PPE and proper ventilation must be followed. Usage of some chemicals requires an occupational exposure monitoring program. (2,3,4)
Utilize the references included in this article to update policies and procedures to ensure that medical devices are thoroughly cleaned and dried before further processing; that the process chosen (i.e., disinfection or sterilization) after cleaning is appropriate for the level of processing needed, and that the disinfection and sterilization process is performed correctly. Ensure that up-to-date instructions for use are available from the medical device manufacturers, and from the manufacturers of the cleaning equipment (i.e., washer decontaminator, brushes, etc.), cleaning agents, disinfectants and sterilizers. And if you include in training and competency testing, you have taken an additional effective step to "Targeting Zero Healthcare-Associated Infections (HAIs)."
(1) Association for the Advancement of Medical Instrumentation. Comprehensive guide to steam sterilization and sterility assurance in health care facilities. ANSI/AAMI ST79:2006, A1:2008 and A2:2009.
(2) The Centers for Disease Control and Prevention (CDC) Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008.
(3) Association for the Advancement of Medical Instrumentation. Chemical sterilization and high-level disinfection in health care facilities. ANSI/AAMI ST58:2005.
(4)The Association for the Advancement of Medical Instrumentation Ethylene oxide sterilization in health care facilities: Safety and effectiveness, ANSI/AAMI ST41: 2008.
A free PDF of the amendment(s) for ST79 may be downloaded by visiting http://www.aami.org/publications/standards/st79.html. This site also includes information on how to update your copy of ST79.
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