Glossary of Medical Sterilization Terms



Accreditation Standards
Is your facility compliant with industry standards as recommended by the CDC, AAMI, AORN, ADA, OSAP, and the Joint Commission? Are you following best practice recommendations? (Some are quoted below with their cross references).

The CDC (Center for Disease Control and Prevention) www.cdc.gov
Recommended Infection-Control Practices for Dentistry, 1993. “Proper functioning of sterilization cycles should be verified by the periodic use (at least weekly) of biological indicators (i.e. spore tests). Heat sensitive chemical indicators (e.g. those that change color after exposure to heat) alone do not ensure adequacy of a sterilization cycle but may be used on the outside of each pack to identify packs that have been processed through the heating cycle. A simple and inexpensive method to confirm heat penetration to all instruments during each cycle is the use of a chemical indicator inside and in the center of either a load of unwrapped instruments or in each multiple instrument pack; this procedure is recommended for use in all dental practices. Instructions provided by the manufacturers of medical/dental instruments and sterilization devices should be followed closely.” Morbidity and Mortality Weekly Report (MMWR) 41(RR-8), May 28, 1993

ADA (American Dental Association) www.ada.org
“This report is based on the recommendations of the Centers for Disease Control and Prevention (see the CDC recommendations above) and other publications in the medical and dental literature. The recommendations in this document have been accepted by the Council on Scientific Affairs and the Council on Dental Practice. The Councils strongly urge practitioners and dental laboratories to comply with these infection control practices…Since this document is not intended to cover every aspect of infection control compliance, the dentist, his or her staff and that of dental laboratories should refer to the referenced publications.” Infection Control Recommendations for the Dental Office and the Dental Laboratory

ANSI / AAMI (American National Standards Institute Inc. / Association for the Advancement of Medical Instrumentation) www.aami.org
“Biological indicators should be used within PCDs for routine sterilizer efficacy monitoring at least weekly, but preferably every day that the sterilizer is in use.” ANSI/AAMI ST79:2006, Section 10.5.3.2

AORN(Association of Perioperative Registered Nurses) www.aorn.org
“For routine monitoring should be used weekly, and as needed; each load of implantables.” Recommended Practices, Sterilization & Disinfection, 1987

OSAP (Organization for Safety & Asepsis Procedures) www.osap.org
“The use and functioning of heat sterilizers should be biologically monitored at least weekly, or more often if the practice demands it, with appropriate spore tests.” Infection Control in Dentistry Guidelines, September 1997

VA (Veteran’s Administration)
“…must be sterilizer monitored no less than weekly, each load of implantables or intravascular materials, following major sterilizer repairs, new products or packaging material.” VA Manual G1, MP-2, Sub-chapter E, Change 159, June 22, 1083

AAP (American Academy of Pediatrics) www.aap.org
Biological indicators are necessary to ensure sterility. A variety of indicator systems are available. The procedure recommended by the manufacturer to document sterility should be done at least weekly and results should be recorded.” (from June 2000 Policy Statement)


Antibody Definition
Antibody is a protein found in the blood that is produced in response to foreign substances (e.g., bacteria or viruses) invading the body. Antibodies protect the body from disease by binding to these organisms and destroying them.

Autoclave Log Record Keeping
Autoclave Log Record Keeping is essential to proper infection control management. Documentation of each sterilizer cycle proves that the cycle was monitored as it was taking place; all parameters to achieving sterility were met; and it also provides accountability. Documentation also helps the staff determine whether a recall of a particular lot or batch is needed should a biological indicator turn positive (a failed test) – suggesting there is a sterility issue. Sterilization records (mechanical, chemical, and biological) should be retained for a time period in compliance with standards (e.g., Joint Commission for the Accreditation of Healthcare Facilities requests 3 years) and state and federal regulations.

The following data should be recorded for every sterilizer cycle.

1. Date, time and operators name or initials
2. The sterilizer’s content and its’ quantity
3. The contents exposure time and temperature (some sterilizers digitally record this)
4. The results of the biological indicator (if used)
5. The results of the Bowie-Dick test (if used)
6. The readout results of the CI (chemical indicator)
7. The lot or load number

Besides the recording of each sterilization cycle, records should also be kept for all repairs or preventative maintenance done on each sterilizer.
A label system should also be used to identify packs or items used in a particular cycle. If a Positive BI occurs, these packs or items can then be culled out easily. If a time-related shelf-life system is used, the label system should include expiration dates to assist in stock rotation. The load record or lot number and the expiration date are noted on the same label. (See Supplies for labels and label dispensers).

Autoclave Testing includes the (1) physical monitoring of the Steam sterilizer (see Mechanical indicator) observing gauges, digital printouts, recorders, displays and/or gauges, (2) the use of external and internal Chemical Indicators (CI’s) and (3) the frequent (at least weekly) use of Biological Indicators (BI’s).
See Proof of Sterilization page showing detail of the three types of monitoring that is required to be done regularly, some with every sterilizer cycle. As per the FDA, “a biological sterilization process indicator is a device intended for use by a health care provider to accompany products being sterilized through a sterilization procedure and to monitor adequacy of sterilization. The device consists of a known number of microorganisms, of known resistance to the mode of sterilization, in or on a carrier and enclosed in a protective package. Subsequent growth or failure of the microorganisms to grow under suitable conditions indicates the adequacy of sterilization.” [21 CFR 880.2800(a)(1)]
A sterilizer that uses steam for its microbicidal process.
Duraline Systems is a Certified Dealer and Service Company for the most prominent brands and manufacturers of autoclaves. This includes supplying sterilizers new or used, repairs, installation, parts or any question you may have related to load capacity or content, time / temperature / pressure needed for your particular sterilizer, etc.

Biological indicators are the only process indicators that directly monitor the lethality of a given sterilization process. Spores used to monitor a sterilization process have demonstrated resistance to the sterilizing agent and are more resistant than the bioburden found on medical devices. Bacillus atrophaeus spores are used to monitor EO Gas and dry heat, and Geobacillus stearothermophilus spores are used to monitor steam sterilization, hydrogen peroxide gas plasma, and liquid peracetic acid sterilizers. Geobacillus stearothermophilus spores are incubated at 55-60°C, and Bacillus atrophaeus spores are incubated at 35-37°C.

Weekly Testing is minimum:

Steam and low temperature sterilizers (e.g., hydrogen peroxide gas plasma, peracetic acid) should be monitored at least weekly with the appropriate commercial preparation of spores. If a sterilizer is used frequently (e.g., several loads per day), daily use of biological indicators allows earlier discovery of equipment malfunctions or procedural errors and thus minimizes the extent of patient surveillance and product recall needed in the event of a positive biological indicator. Each load should be monitored if it contains implantable objects. If feasible, implantable items should not be used until the results of spore tests are known to be negative. See also www.cdc.gov/oralhealth/infectioncontrol/faq/steri...
The excellent microbicidal activity of ETO sterilizers has been demonstrated and proven in several studies. ETO inactivates all microorganisms although bacterial spores (especially Bacillus atrophaeus) are more resistant than other microorganisms. For this reason Bacillus atrophaeus spores is the recommended biological indicator. Also, Bacillus atrophaeus spores should be used to monitor the sterilization process for dry heat because they are more resistant to dry heat than are Geobacillus stearothermophilus spores. The primary lethal process is considered to be oxidation of cell constituents.

The number and types of viable microorganisms with which an item is contaminated; this is also called bioload or microbial load. Bioburden is microorganisms existing on a product, instrument, device and/or package.

The most important step to decontaminating all reusable medical devices is thorough cleaning and rinsing. This doesn’t kill microorganisms, but removes the bioburden masses, which is then followed by a disinfection or sterilization process. Prior to cleaning, instruments should be presoaked in enzymatic solution and thoroughly rinsed afterwards. This loosens the bioburden to allow for thorough cleaning of the device.

As there are many different types of medical devices which include trays, containers, instruments, etc., it is therefore critical that users follow manufacturer’s recommendations for proper cleaning, prior to disinfection or sterilization.

Microorganisms may be protected from disinfectants by production of thick masses of cells and extracellular materials, or biofilms. Biofilms are microbial communities that are tightly attached to surfaces and cannot be easily removed. Once these masses form, microbes within them can be resistant to disinfectants by multiple mechanisms, including physical characteristics of older biofilms, genotypic variation of the bacteria, microbial production of neutralizing enzymes, and physiologic gradients within the biofilm (e.g., pH). Bacteria within biofilms are up to 1,000 times more resistant to antimicrobials than are the same bacteria in suspension. Although new decontamination methods are being investigated for removing biofilms, chlorine and monochloramines can effectively inactivate biofilm bacteria. Biofilms have been found in whirlpools, dental unit waterlines, and numerous medical devices (e.g., contact lenses, pacemakers, hemodialysis systems, urinary catheters, central venous catheters, endoscopes). Their presence can have serious implications for immune-compromised patients and patients who have indwelling medical devices. Some enzymes and detergents can degrade biofilms or reduce numbers of viable bacteria within a biofilm, but no products are EPA-registered or FDA-cleared for this purpose. See also Bioburden.

See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Biological indicators are a device to monitor the sterilization process that consists of a standardized population of bacterial spores known to be resistant to the mode of sterilization being monitored. Biological indicators indicate that all the parameters necessary for sterilization were present. As per the FDA, “a biological sterilization process indicator is a device intended for use by a health care provider to accompany products being sterilized through a sterilization procedure and to monitor adequacy of sterilization. The device consists of a known number of microorganisms, of known resistance to the mode of sterilization, in or on a carrier and enclosed in a protective package. Subsequent growth or failure of the microorganisms to grow under suitable conditions indicates the adequacy of sterilization.” [21 CFR 880.2800(a)(1)] Biological indicators are recognized by most authorities as being closest to the ideal monitors of the sterilization process because they measure the sterilization process directly by using the most resistant microorganisms (i.e., Bacillus spores), and not by merely testing the physical and chemical conditions necessary for sterilization. Since the Bacillus spores used in biological indicators are more resistant and present in greater numbers than are the common microbial contaminants found on patient-care equipment, the demonstration that the biological indicator has been inactivated strongly implies that other potential pathogens in the load have been killed.

Bloodborne pathogens are pathogenic microorganisms that are present in human blood and can cause disease in humans. These pathogens include, but are not limited to, hepatitis B virus (HBV) and human immunodeficiency virus (HIV). They are disease-producing microorganisms spread by contact with blood or other body fluids contaminated with blood from an infected person.

A Bowie-Dick test is used in pre-vacuum type (or dynamic air removal) sterilizers. They are used to detect air leaks and inadequate air removal and consist of folded 100% cotton surgical towels that are clean and preconditioned. A commercially available Bowie-Dick-type test sheet should be placed in the center of the pack. The test pack should be placed horizontally in the front, bottom section of the sterilizer rack, near the door and over the drain, in an otherwise empty chamber and run at 134°C for 3.5 minutes. The test is used each day the vacuum-type steam sterilizer is used, before the first processed load. Air that is not removed from the chamber will interfere with steam contact. Smaller, commercially available disposable test packs (or process challenge devices) have been devised to replace the stack of folded surgical towels for testing the efficacy of the vacuum system in a prevacuum sterilizer. They should be representative of the load and simulate the greatest challenge to the load. Sterilizer vacuum performance is acceptable if the sheet inside the test pack shows a uniform color change. Entrapped air will cause a spot to appear on the test sheet, due to the inability of the steam to reach the chemical indicator. If the sterilizer fails the Bowie-Dick test, do not use the sterilizer until it is inspected by the sterilizer maintenance personnel and passes the Bowie-Dick test.

See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Contact: Toll-Free #(800)CDC-INFO or check CDC’s website at: www.cdc.gov
"Monitor sterilizers at least weekly by using a biological indicator with a matching control (i.e., biological indicator and control from same lot number)." Guidelines for infection control in dental health-care settings - 2003. Morbidity and Mortality Weekly Report (MMWR), 52(RR-17), 19 December 2003.

“Use a biological indicator for every sterilizer load that contains an implantable device…” Guidelines for infection control in dental health-care settings - 2003. Morbidity and Mortality Weekly Report (MMWR), 52(RR-17)(243-248) 19 December 2003.

"All sterilizers should be monitored at least once a week with commercial preparations of spores intended specifically for the type of sterilizer." Gamer JS, Favero MS. CDC guideline for hand washing and Hospital environment control 1985. Infection Control 7(231-43), 1986.

"The adequacy of sterilization cycles should be verified by the periodic use of spore - testing devices (e.g., weekly for most dental practices)." Recommended Infection-Control Practices for Dentistry, Morbidity and Mortality Weekly Report (MMWR), 35(237-42), 1986.

“Proper functioning of sterilization cycles should be verified by the periodic use (at least weekly) of biological indicators (i.e. spore tests). Heat sensitive chemical indicators (e.g. those that change color after exposure to heat) alone do not ensure adequacy of a sterilization cycle but may be used on the outside of each pack to identify packs that have been processed through the heating cycle. A simple and inexpensive method to confirm heat penetration to all instruments during each cycle is the use of a chemical indicator inside and in the center of either a load of unwrapped instruments or in each multiple instrument pack; this procedure is recommended for use in all dental practices. Instructions provided by the manufacturers of medical/dental instruments and sterilization devices should be followed closely.”
Recommended Infection-Control Practices for Dentistry, 1993. Morbidity and Mortality Weekly Report (MMWR), 41(RR-8), 28 May 1993.

“Steam and low temperature sterilizers (e.g., hydrogen peroxide gas plasma, peracetic acid) should be monitored at least weekly with the appropriate commercial preparation of spores. If a sterilizer is used frequently (e.g., several loads per day), daily use of biological indicators allows earlier discovery of equipment malfunctions or procedural errors and thus minimizes the extent of patient surveillance and product recall needed in the event of a positive biological indicator. Each load should be monitored if it contains implantable objects. If feasible, implantable items should not be used until the results of spore tests are known to be negative.” See www.cdc.gov Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008

In dental health care settings, all instrument cleaning, disinfecting, and sterilizing should occur in a designated central processing area in order to more easily control quality and ensure safety. The instrument processing area should be physically divided into sections for 1) receiving, cleaning, and decontamination; 2) preparation and packaging; 3) sterilization; and 4) storage. This division is designed to contain contaminated items in an area designed specifically for cleaning, thus preventing contamination of the clean areas where packaging, sterilization, and storage of sterile items occurs. Reusable contaminated instruments and devices are received, sorted, and cleaned in the cleaning area. The packaging area is for inspecting, assembling, and packaging clean instruments in preparation for final processing. The sterilization and storage areas contain the sterilizers and related supplies, as well as incubators for analyzing spore tests, and can contain enclosed storage for sterile items and disposable (single-use) items. When it is not possible to have physical separation of these areas, clearly labeling each area (e.g., from contaminated to sterile) might be satisfactory if the personnel who process the instruments are trained in work practices to prevent contamination of clean areas.

Chemical indicators are one of the three critical devices for monitoring a sterilization process. They are designed to respond with a characteristic chemical or physical change to one or more of the physical conditions within the sterilizing chamber. Chemical indicators are intended to detect potential sterilization failures immediately that could result from incorrect packaging, incorrect loading of the sterilizer, or malfunctions of the sterilizer. The Association for the Advancement of Medical Instrumentation has defined five classes of chemical indicators: Class 1 (process indicator); Class 2 (Bowie-Dick test indicator); Class 3 (single-parameter indicator); Class 4 (multi-parameter indicator); and Class 5 (integrating indicator).

FDA defines a physical*/chemical sterilization process indicator (21 CFR 880.2800(b)) as: A device intended for use by a health care provider to accompany products being sterilized through a sterilization procedure and to monitor one or more parameters of the sterilization process. The adequacy of the sterilization conditions as measured by these parameters is indicated by a visible change in the device.

Compared to biological indicators:
In one study, chemical indicators were more likely than biological indicators to inaccurately indicate sterilization at marginal sterilization times (e.g., 2 minutes). Chemical indicators should be used in conjunction with biological indicators, but based on current studies should not replace them because they indicate sterilization at marginal sterilization time and because only a biological indicator consisting of resistant spores can measure the microbicidal killing power of the sterilization process.

Placement of chemical indicators:
Chemical indicators are affixed on the outside of each pack to show that the package has been processed through a sterilization cycle, but these indicators do not prove sterilization has been achieved. Preferably, a chemical indicator also should be placed on the inside of each pack to verify sterilant penetration. Chemical indicators usually are either heat-or chemical-sensitive inks that change color when one or more sterilization parameters (e.g., steam-time, temperature, and/or saturated steam; ETO-time, temperature, relative humidity and/or ETO concentration) are present. If the internal and/or external indicator suggests inadequate processing, the item should not be used. An air-removal test (Bowie-Dick Test – a Class 2 indicator) must be performed daily in an empty dynamic-air-removal sterilizer (e.g., prevacuum steam sterilizer) to ensure air removal.

IMPORTANT NOTE: The “pass” response of a chemical indicator does not prove the item accompanied by the indicator is necessarily sterile.

Indicators come in many different forms including on autoclave tape, labels, pouches, Bowie-Dick Tests and more

Chemical Vapor Sterilization process uses a solution of alcohol, water, and trace formaldehyde which is heated to produce an unsaturated vapor that must reach a specified temperature, pressure and exposure time in order to achieve sterility. Users should follow the sterilizer manufacturers’ strict guidelines for proper packaging, loading and operation of this type of sterilizer.

Cleaning is the removal of foreign material (e.g., soil, and organic material) from objects and is normally accomplished using water with detergents or enzymatic products. Thorough cleaning is required before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments interfere with the effectiveness of these processes. Also, if soiled materials dry or bake onto the instruments, the removal process becomes more difficult and the disinfection or sterilization process less effective or ineffective. Surgical instruments should be presoaked or rinsed to prevent drying of blood and to soften or remove blood from the instruments.

Manual cleaning is done in use areas without mechanical units (e.g., ultrasonic cleaners or washer-disinfectors) or for fragile or difficult-to-clean instruments. With manual cleaning, the two essential components are friction and fluidics. Friction (e.g., rubbing/scrubbing the soiled area with a brush) is an old and dependable method. Fluidics (i.e., fluids under pressure) is used to remove soil and debris from internal channels after brushing and when the design does not allow passage of a brush through a channel. When a washer-disinfector is used, care should be taken in loading instruments: hinged instruments should be opened fully to allow adequate contact with the detergent solution; stacking of instruments in washers should be avoided; and instruments should be disassembled as much as possible. For more detail on manual cleaning, see The Center For Disease Controls “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008” at www.cdc.gov.
Cleaning is the removal of foreign material (e.g., soil, and organic material) from objects and is normally accomplished using water with detergents or enzymatic products. Thorough cleaning is required before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments interfere with the effectiveness of these processes. Mechanical Cleaning is the preferred method to cleaning instruments or devices – known to be 16 times more effective then cleaning manually.

The most common types of mechanical or automatic cleaners are ultrasonic cleaners, washer-decontaminators, washer-disinfectors, and washer-sterilizers.

Ultrasonic cleaning removes soil by cavitation and implosion in which waves of acoustic energy are propagated in aqueous solutions to disrupt the bonds that hold particulate matter to surfaces. Bacterial contamination can be present in used ultrasonic cleaning solutions (and other used detergent solutions) because these solutions generally do not make antibacterial label claims. Even though ultrasound alone does not significantly inactivate bacteria, sonication can act synergistically to increase the cidal efficacy of a disinfectant. Users of ultrasonic cleaners should be aware that the cleaning fluid could result in endotoxin contamination of surgical instruments, which could cause severe inflammatory reactions.

Washer-sterilizers are modified steam sterilizers that clean by filling the chamber with water and detergent through which steam passes to provide agitation. Instruments are subsequently rinsed and subjected to a short steam-sterilization cycle. Another washer-sterilizer employs rotating spray arms for a wash cycle followed by a steam sterilization cycle at 285°F.

Washer-decontaminators/disinfectors act like a dishwasher that uses a combination of water circulation and detergents to remove soil. These units sometimes have a cycle that subjects the instruments to a heat process (e.g., 93°C for 10 minutes). Washer-disinfectors are generally computer-controlled units for cleaning, disinfecting, and drying solid and hollow surgical and medical equipment.

See the complete recommendations on cleaning, disinfection and sterilization at www.cdc.gov.
“Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Automated cleaning (or mechanical cleaning) is the preferred method to cleaning instruments or devices – known to be 16 times more effective then manual cleaning. Because instruments cleaned with automated cleaning equipment do not need to be presoaked or scrubbed, the use of automated equipment can increase productivity, improve cleaning effectiveness, and decrease worker exposure to blood and body fluids. Thus, using automated equipment can be more efficient and safer than manually cleaning contaminated instruments.

Automated cleaning and rinsing process utilize equipment such as: Utensil or cart washers, washer-sterilizer, pasteurization equipment, washer-disinfectors, or washer-sanitizers. Considerations in selecting cleaning methods and equipment include their effectiveness, their compatibility with the items to be cleaned, and the occupational health and exposure risks they pose. Some are made to clean specific devices, such as endoscopes. It is recommended that the manufacturer’s instruction manual of the cleaning equipment be followed for maximum effectiveness and to avoid unnecessary damage to the devices being cleaned.

Ultrasonic cleaners are used to do fine-cleaning of complex instruments, removing soil from joints, crevices, lumens and other difficult to clean areas. This process is done only after removal of heavy soil using equipment mentioned above, or by manual cleaning. Ultrasonic cleaning does not disinfect or sterilize. The cleaning solution for ultrasonic cleaners should be changed before it becomes heavily soiled, minimizing the risk of cross-contamination. Not all devices can be intermixed in the ultrasonic cleaning process. The manufacturer of the device should specify any restrictions.

See the complete recommendations on cleaning, disinfection and sterilization at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

The state of having actual or potential contact with microorganisms. As used in health care, the term generally refers to the presence of microorganisms that could produce disease or infection.

A Control BI is a biological indicator from the same lot as a test indicator that is left unexposed to the sterilization cycle and then incubated to verify the viability of the test indicator. The control indicator should yield positive results for bacterial growth.

Decontamination is a process or treatment that renders a medical device, instrument, or environmental surface safe to handle. Decontamination is, 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]. Proper cleaning of instruments or devices involves a multi-step process, which includes: Presoaking, disassembling, cleaning, rinsing, packaging, sterilization, storage and shelf-life. See other recommendations on decontamination at www.cdc.gov . See also “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Disassembling of instruments that have more than one part is required to expose all surfaces to the cleaning process (e.g. procedure needles, dental hand pieces, laparoscopic instrumentation, rigid containers…etc). Medical instruments with multiple pieces must be disassembled and equipment such as endoscopes that have crevices, joints, and channels are more difficult to disinfect than are flat- surface equipment because penetration of the disinfectant of all parts of the equipment is more difficult.

A chemical agent used on non-living objects (e.g., floors, walls, sinks) to destroy virtually all recognized pathogenic microorganisms, but not necessarily all microbial forms (e.g., bacterial endospores). The EPA groups disinfectants on whether the product label claims "limited," "general" or "hospital" disinfectant. Disinfection is generally a less lethal process than sterilization. It eliminates nearly all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial spores) on inanimate objects. Disinfection does not ensure an “overkill'' and therefore lacks the margin of safety achieved by sterilization procedures.

The effectiveness of a disinfection procedure is controlled significantly by a number of factors, each one of which may have a pronounced effect on the end result. Among these are:
• the nature and number of contaminating microorganisms (especially the presence of bacterial spores);
• the amount of organic matter present (e.g., soil, feces, and blood);
• the type and condition of instruments, devices, and materials to be disinfected;
• the temperature.

Disinfection is a procedure that reduces the level of microbial contamination, but there is a broad range of activity that extends from sterility at one extreme to a minimal reduction in the number of microbial contaminants at the other. By definition, chemical disinfection and in particular, high-level disinfection differs from chemical sterilization by its lack of sporicidal power. This is an over simplification of the actual situation because a few chemical germicides used as disinfectants do, in fact, kill large numbers of spores even though high concentrations and several hours of exposure may be required. Non-sporicidal disinfectants may differ in their capacity to accomplish disinfection or decontamination. Some germicides rapidly kill only the ordinary vegetative forms of bacteria such as staphylococci and streptococci, some forms of fungi, and lipid containing viruses, whereas others are effective against such relatively resistant organisms as Mycobacterium tuberculosis var. bovis, non-lipid viruses, and most forms of fungi.

Many disinfectants are used alone or in combinations (e.g., hydrogen peroxide and peracetic acid) in the health-care setting. These include alcohols, chlorine and chlorine compounds, formaldehyde, glutaraldehyde, ortho-phthalaldehyde, hydrogen peroxide, iodophors, peracetic acid, phenolics, and quaternary ammonium compounds. Commercial formulations based on these chemicals are considered unique products and must be registered with EPA or cleared by FDA. In most instances, a given product is designed for a specific purpose and is to be used in a certain manner. Therefore, users should read labels carefully to ensure the correct product is selected for the intended use and applied efficiently. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Distilled water is water heated to boiling point, vaporized, cooled, condensed, and collected so that no impurities are reintroduced.
Most sterilizer manufacturers require that distilled water is used for steam sterilizers. Using tap water will adversely affect the quality of the steam and cause sterilization failures and possibly damage the sterilizer itself. ATS, Inc. offers quality water distillers allowing you to distill your own tap water.
Advantages in buying a water distiller:
1. No longer need to transport heavy gallons of distilled water!
2. Store-bought distilled water costs average of $1.20 versus tap water costs 10-15¢ per gallon.
3. IT’S HEALTHY FOR YOU TOO – not just for your sterilizer! Distilled water is great drinking water as it is PURE water - all impurities are boiled off.

Dry Heat sterilization should be used only for materials that might be damaged by moist heat or that are impenetrable to moist heat (e.g., powders, petroleum products, sharp instruments). The primary lethal process is considered to be oxidation of cell constituents. The most common time-temperature relationships for sterilization with hot air sterilizers are 170°C (340°F) for 60 minutes, 160°C (320°F) for 120 minutes, and 150°C (300°F) for 150 minutes.

Advantages and Disadvantages of Dry Heat Sterilization:
The advantages for dry heat include the following: it is nontoxic and does not harm the environment; a dry heat cabinet is easy to install and has relatively low operating costs; it penetrates materials; and it is noncorrosive for metal and sharp instruments. The disadvantages for dry heat are the slow rate of heat penetration and microbicidal killing makes this a time-consuming method. In addition, the high temperatures are not suitable for most materials.

Two Types of Dry Heat Sterilizers:
There are two types of dry-heat sterilizers: the static-air type and the forced-air type. The static-air type is referred to as the oven-type sterilizer as heating coils in the bottom of the unit cause the hot air to rise inside the chamber via gravity convection. This type of dry-heat sterilizer is much slower in heating, requires longer time to reach sterilizing temperature, and is less uniform in temperature control throughout the chamber than is the forced-air type. The forced-air or mechanical convection sterilizer is equipped with a motor-driven blower that circulates heated air throughout the chamber at a high velocity, permitting a more rapid transfer of energy from the air to the instruments. ATS, Inc. offers a quality line of Dry Heat sterilizers – compare our prices!

Spore Testing Dry Heat Sterilizers:
Bacillus atrophaeus spores should be used to monitor the sterilization process for dry heat because they are more resistant to dry heat than are Geobacillus stearothermophilus spores.
Autoclave Testing Service, Inc. spore tests all sterilizers, not just autoclaves (steam sterilizers). For spore testing Dry Heat sterilizers, the microbiology laboratory uses Bacillus atrophaeus spores which are cultured at 35°C. We offer immediate notification of positive tests (spores that show growth indicating sterilizer failure). Most failed tests show up within 24 to 48 hours and you will be immediately notified. ATS, Inc. is also a supplier of Dry Heat sterilizers – see New or Used sterilizers.

Ethylene Oxide sterilization is a low temperature sterilization process designed to sterilize instruments or devices that are sensitive to heat and/or moisture. ETO is a colorless gas that is flammable and explosive. The four essential parameters (operational ranges) are: gas concentration (450 to 1200 mg/l); temperature (37 to 63°C); relative humidity (40 to 80%) (water molecules carry ETO to reactive sites); and exposure time (1 to 6 hours). These influence the effectiveness of ETO sterilization. Within certain limitations, an increase in gas concentration and temperature may shorten the time necessary for achieving sterilization.

The basic ETO sterilization cycle consists of five stages (i.e., preconditioning and humidification, gas introduction, exposure, evacuation, and air washes) and takes approximately 2-1/2 hrs excluding aeration time. Mechanical aeration for 8 to 12 hours at 50 to 60°C allows desorption of the toxic ETO residual contained in exposed absorbent materials. Most modern ETO sterilizers combine sterilization and aeration in the same chamber as a continuous process. These ETO models minimize potential ETO exposure during door opening and load transfer to the aerator. Ambient room aeration also will achieve desorption of the toxic ETO but requires 7 days at 20°C. There are no federal regulations for ETO sterilizer emission; however, many states have promulgated emission-control regulations.

Microbicidal Activity:
The excellent microbicidal activity of ETO has been demonstrated in several studies and summarized in published reports. ETO inactivates all microorganisms although bacterial spores (especially Bacillus atrophaeus) are more resistant than other microorganisms. For this reason B. atrophaeus is the recommended biological indicator. Like all sterilization processes, the effectiveness of ETO sterilization can be altered by lumen length, lumen diameter, inorganic salts, and organic materials. For example, although ETO is not used commonly for reprocessing endoscopes, several studies have shown failure of ETO in inactivating contaminating spores in endoscope channels or lumen test units and residual ETO levels averaging 66.2 ppm even after the standard degassing time. Failure of ETO also has been observed when dental handpieces were contaminated with Streptococcus mutans and exposed to ETO. It is recommended that dental handpieces be steam sterilized.

Uses:
ETO is used in healthcare facilities to sterilize critical items (and sometimes semi-critical items) that are moisture or heat sensitive and cannot be sterilized by steam sterilization. The use of ETO evolved when few alternatives existed for sterilizing heat- and moisture-sensitive medical devices; however, favorable properties account for its continued widespread use. Two ETO gas mixtures are available to replace ETO-chlorofluorocarbon (CFC) mixtures for large capacity, tank-supplied sterilizers. The ETO-carbon dioxide (CO2) mixture consists of 8.5% ETO and 91.5% CO2. This mixture is less expensive than ETO-hydro chlorofluorocarbons (HCFC), but a disadvantage is the need for pressure vessels rated for steam sterilization, because higher pressures (28-psi gauge) are required. The other mixture, which is a drop-in CFC replacement, is ETO mixed with HCFC.

Following the sterilization cycle:
ETO is absorbed by many materials. For this reason, following sterilization the item must undergo aeration to remove residual ETO. Guidelines have been promulgated regarding allowable ETO limits for devices that depend on how the device is used, how often, and how long in order to pose a minimal risk to patients in normal product use.

Disadvantages / hazardous:
The main disadvantages associated with ETO are the lengthy cycle time, the cost, and its potential hazards to patients and staff; the main advantage is that it can sterilize heat- or moisture-sensitive medical equipment without deleterious effects on the material used in the medical devices. Acute exposure to ETO may result in irritation (e.g., to skin, eyes, gastrointestinal or respiratory tracts) and central nervous system depression. Chronic inhalation has been linked to the formation of cataracts, cognitive impairment, neurologic dysfunction, and disabling polyneuropathies. Occupational exposure in healthcare facilities has been linked to hematologic changes and an increased risk of spontaneous abortions and various cancers. ETO should be considered a known human carcinogen.

Damaging to ozone:
HCFCs are approximately 50-fold less damaging to the earth’s ozone layer than are CFCs. The EPA will begin regulation of HCFC in the year 2015 and will terminate production in the year 2030. Two companies provide ETO-HCFC mixtures as drop-in replacement for CFC-12; one mixture consists of 8.6% ETO and 91.4% HCFC, and the other mixture is composed of 10% ETO and 90% HCFC. An alternative to the pressurized mixed gas ETO systems is 100% ETO. The 100% ETO sterilizers using unit-dose cartridges eliminate the need for external tanks.

ETO Exposure:
ETO toxicity has been established in a variety of animals. Exposure to ETO can cause eye pain, sore throat, difficulty breathing and blurred vision. Exposure can also cause dizziness, nausea, headache, convulsions, blisters and vomiting and coughing. In a variety of in vitro and animal studies, ETO has been demonstrated to be carcinogenic. ETO has been linked to spontaneous abortion, genetic damage, nerve damage, peripheral paralysis, muscle weakness, and impaired thinking and memory. Occupational exposure in healthcare facilities has been linked to an increased risk of spontaneous abortions and various cancers. Injuries (e.g., tissue burns) to patients have been associated with ETO residues in implants used in surgical procedures. Residual ETO in capillary flow dialysis membranes has been shown to be neurotoxic in vitro. OSHA has established a PEL of 1 ppm airborne ETO in the workplace, expressed as a TWA for an 8-hour work shift in a 40-hour work week. The “action level” for ETO is 0.5 ppm, expressed as an 8-hour TWA, and the short-term excursion limit is 5 ppm, expressed as a 15-minute TWA. Several personnel monitoring methods (e.g., charcoal tubes and passive sampling devices) are in use. OSHA has established a PEL of 5 ppm for ethylene chlorohydrin (a toxic by-product of ETO) in the workplace. Additional information regarding use of ETO in health care facilities is available from NIOSH. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

A storage practice that recognizes that a package and its contents should remain sterile until some event causes the item(s) to become contaminated.

Although some hospitals continue to date every sterilized product and use the time-related shelf-life practice, many hospitals have switched to an event-related shelf-life practice. This latter practice recognizes that the product should remain sterile until some event causes the item to become contaminated (e.g., tear in packaging, packaging becomes wet, seal is broken). Event-related factors that contribute to the contamination of a product include bioburden (i.e., the amount of contamination in the environment), air movement, traffic, location, humidity, insects, vermin, flooding, storage area space, open/closed shelving, temperature, and the properties of the wrap material.

There is data that support the event-related shelf-life practice; one study examined the effect of time on the sterile integrity of paper envelopes, peel pouches, and nylon sleeves. The most important finding was the absence of a trend toward an increased rate of contamination over time for any pack when placed in covered storage. Another evaluated the effectiveness of event-related outdating by microbiologically testing sterilized items. During the 2-year study period, all of the items tested were sterile. Thus, contamination of a sterile item is event-related and the probability of contamination increases with increased handling. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Flash sterilization is a sterilization process that allows for immediate use of patient care items, performed at the time of a surgical procedure. Flash-sterilized items or devices are to be used immediately following sterilization.

When using flash sterilization, make sure the following parameters are met:
1. Clean the item before placing it in the sterilizing container (that are FDA cleared for use with flash sterilization) or tray;
2. Prevent exogenous contamination of the item during transport from the sterilizer to the patient;
3. Monitor sterilizer function with mechanical, chemical, and biologic monitors.

EXCEPTION: Do not flash sterilize implanted surgical devices unless doing so is unavoidable. Do not use flash sterilization for convenience, as an alternative to purchasing additional instrument sets, or to save time. Do not use packaging materials and containers in flash sterilization cycles unless the sterilizer and the packaging material/container are designed for this use.

When necessary, use flash sterilization for patient-care items that will be used immediately (e.g., to reprocess an inadvertently dropped instrument). Also, when necessary, use flash sterilization for processing patient-care items that cannot be packaged, sterilized, and stored before use. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Biological indicators are the only process indicators that directly monitor the lethality of a given sterilization process. Spores used to monitor a sterilization process have demonstrated resistance to the sterilizing agent and are more resistant than the bioburden found on medical devices. While Bacillus atrophaeus spores are used to monitor ETO and dry heat sterilizers, Geobacillus stearothermophilus spores are used to monitor steam sterilization, hydrogen peroxide gas plasma, and liquid peracetic acid sterilizers. Geobacillus stearothermophilus spores are incubated at 55-60°C and Bacillus atrophaeus spores are incubated at 35-37°C.

Weekly testing is minimum:
Steam and low temperature sterilizers (e.g., hydrogen peroxide gas plasma, peracetic acid) should be monitored at least weekly with the appropriate commercial preparation of Geobacillus stearothermophilus spores. If a sterilizer is used frequently (e.g., several loads per day), daily use of biological indicators allows earlier discovery of equipment malfunctions or procedural errors and thus minimizes the extent of patient surveillance and product recall needed in the event of a positive biological indicator. Each load should be monitored if it contains implantable objects. If feasible, implantable items should not be used until the results of spore tests are known to be negative. See also www.cdc.gov/oralhealth/infectioncontrol/faq/steri...

Originally, spore-strip biological indicators required up to 7 days of incubation to detect viable spores from marginal cycles (i.e., when few spores remained viable). The next generation of biological indicator was self-contained in plastic vials containing a spore-coated paper strip and a growth media in a crushable glass ampoule. This indicator had a maximum incubation of 48 hours but significant failures could be detected in ≤24 hours. A rapid-readout biological indicator that detects the presence of enzymes of Geobacillus stearothermophilus by reading a fluorescent product produced by the enzymatic breakdown of a non-fluorescent substrate has been marketed for the more than 10 years. Studies demonstrate that the sensitivity of rapid-readout tests for steam sterilization (1 hour for 132°C gravity sterilizers, 3 hrs for 121°C gravity and 132°C vacuum sterilizers) parallels that of the conventional sterilization-specific biological indicators and the fluorescent rapid readout results reliably predict 24 and 48-hour and 7-day growth. The rapid-readout biological indicator is a dual indicator system as it also detects acid metabolites produced during growth of the Geobacillus stearothermophilus spores. This system is different from the indicator system consisting of an enzyme system of bacterial origin without spores. Independent comparative data using suboptimal sterilization cycles (e.g., reduced time or temperature) with the enzyme-based indicator system have not been published. ATS, Inc. also has a rapid readout system available – see Biological Indicators.

Germicide is an agent that destroys microorganisms, especially pathogenic organisms. Other terms with the suffix "–cide" (e.g., virucide, fungicide, bactericide, tuberculocide, sporicide) are agents that destroy the microorganism noted in the prefix. Germicides may be used to inactivate microorganisms in or on living tissue (antiseptic) or on environmental surfaces (disinfectants).

Huck towel is an all-cotton surgical towel with a honey-comb weave; both warp and fill yarns are tightly twisted. Huck towels can be used to prepare biological indicator challenge test packs (or PCD’s).

According to the Food and Drug Administration (FDA), "device that is placed into a surgically or naturally formed cavity of the human body if it is intended to remain there for a period of 30 days or more" [21 CFR 812.3(d)].

Sterilizing implantable devices:
Because of the potential for serious infections, flash sterilization is not recommended for implantable devices (i.e., devices placed into a surgically or naturally formed cavity of the human body); however, flash sterilization may be unavoidable for some devices (e.g., orthopedic screw, plates). If flash sterilization of an implantable device is unavoidable, recordkeeping (i.e., load identification, patient’s name/hospital identifier, and biological indicator result) is essential for epidemiological tracking (e.g., of surgical site infection, tracing results of biological indicators to patients who received the item to document sterility), and for an assessment of the reliability of the sterilization process (e.g., evaluation of biological monitoring records and sterilization maintenance records noting preventive maintenance and repairs with dates). See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Steam sterilization is commonly used by on-site medical centers and hospitals for their medical waste treatment. Many such facilities are periodically monitoring the efficacy of their sterilization process with Biological Indicators (BIs). In most states, the Dept. of Health has set up regulations requiring the periodic monitoring of such sterilization cycles. The BIs commonly used to monitor the steam sterilization cycles are spore strips or small crushable types of plastic self-contained indicators.

THE PROBLEM:
A common but inappropriate method used to monitor the sterilization cycles for medical or micro lab waste is where the spore strips are placed directly into the bag of medical waste prior to sterilization. The load is processed and upon cycle completion, the spore strips are removed. The strips must then be transferred aseptically to a tube of culture media and incubated for growth / no growth testing. The spore strip transfers could be done on-site or by a contract laboratory where testing results and documented and the testing records are maintained as evidence that sterilization monitoring has been done.

During the sterilization cycle, much of the medical waste that consists of used IV bags, plastic tubing partially filled with remaining fluids, blood agar Petri dishes and other such items tend to melt and leak their fluid content into the bio-waste bag being sterilized. This liquid and melted agar often gets onto the spore strips or on and around the plastic self-contained biological indicator. When such a situation exists, liquid and melted agar can come into contact with the spore strips and the actual performance of the spore strip may be compromised and your test results no longer accurate and reliable.

IMPORTANT: Spore strips are not intended for use in cycles similar to liquid loads where they may become wet and coated with waste debris.


THE SOLUTION:
The preferred method is to use a sealed glass ampoule type BI designed specifically for such cycles where liquids are going to be present. These glass ampoules contain the same spores that would be used on a spore strip and they also contain the growth media that would be in the tube that a spore strip is transferred to. Therefore the need to aseptically transfer to growth media is eliminated. One simply inserts the ampoule into the bag being sterilized and upon completion of the sterilization cycle the ampoule is removed and is placed directly into the incubator. Simply, sterilize and then incubate! No other steps are required.

The media in the ampoule contains a pH indicator so that with incubation, if the bacteria in the ampoule grow, the media changes from a bright purple color to a bright yellow color. If the sterilization cycle was successful, the ampoule remains purple. The required incubation time for these ampoules is only 48 hours and not a full 7 days as with most spore strips. Ease of placement into and out of the biobag is much more convenient than with spore strips. The upper portion of the ampoule has a collared or grooved area in the glass. A long string or wire can be attached to the ampoule at this area as shown above. The ampoule is placed into the biobag with the string hanging out of the bag. When the cycle is finished, the ampoule is retrieved by pulling on the string. The ampoule is then wiped off and placed directly into the incubator. It’s that simple! No transfers needed!
A small table top incubator can be purchased that will hold up to 12 ampoules at one time. The incubator is preset for temperature and the ampoules are easily visible to monitor for color change. After 48 hours of incubation, if no color changes occur, the ampoules can be removed and disposed of.

Mechanical indicators are devices such as gauges, meter, display, or printout from a sterilizer display an element of the sterilization process (e.g., time, temperature, pressure). This is of the three parameters required to monitor sterilizer cycles. Internal and external chemical indicators and biological indicators are to be used along with mechanical monitoring of sterilizer, to ensure sterilization is being reached in every cycle.

MECHANICAL INDICATOR Microbicidal methods (lethal kill of microorganisms) include disinfection or sterilization by thermal or chemical means. This is the final step in the decontamination process. Knowledge is critical in selecting the correct microbicidal process as it depends on the device manufacturers’ recommendations, the manufacturer of the disinfectant solution and what the device has been exposed to. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Thorough cleaning required before disinfection and sterilization:
All other conditions remaining constant, the larger the number of microbes, the more time a germicide needs to destroy all of them. Spaulding illustrated this relation when he employed identical test conditions and demonstrated that it took 30 minutes to kill 10 Bacillus atrophaeus (formerly Bacillus subtilis) spores but 3 hours to kill 100,000 Bacillus atrophaeus spores. This reinforces the need for scrupulous cleaning of medical instruments before disinfection and sterilization. Reducing the number of microorganisms that must be inactivated through meticulous cleaning, increases the margin of safety when the germicide is used according to the labeling and shortens the exposure time required to kill the entire microbial load. Accessibility of sterilant to microorganisms:
The location of microorganisms also must be considered when factors affecting the efficacy of germicides are assessed. Medical instruments with multiple pieces must be disassembled and equipment such as endoscopes that have crevices, joints, and channels are more difficult to disinfect than are flat-surface equipment because penetration of the disinfectant of all parts of the equipment is more difficult. Only surfaces that directly contact the germicide will be disinfected, so there must be no air pockets and the equipment must be completely immersed for the entire exposure period. Manufacturers should be encouraged to produce equipment engineered for ease of cleaning and disinfection. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.
Thorough cleaning required before disinfection and sterilization: All other conditions remaining constant, the larger the number of microbes, the more time a germicide needs to destroy all of them. Spaulding illustrated this relation when he employed identical test conditions and demonstrated that it took 30 minutes to kill 10 Bacillus atrophaeus (formerly Bacillus subtilis) spores but 3 hours to kill 100,000 Bacillus atrophaeus spores. This reinforces the need for scrupulous cleaning of medical instruments before disinfection and sterilization. Reducing the number of microorganisms that must be inactivated through meticulous cleaning, increases the margin of safety when the germicide is used according to the labeling and shortens the exposure time required to kill the entire microbial load. Accessibility of sterilant to microorganisms: The location of microorganisms also must be considered when factors affecting the efficacy of germicides are assessed. Medical instruments with multiple pieces must be disassembled and equipment such as endoscopes that have crevices, joints, and channels are more difficult to disinfect than are flat-surface equipment because penetration of the disinfectant of all parts of the equipment is more difficult. Only surfaces that directly contact the germicide will be disinfected, so there must be no air pockets and the equipment must be completely immersed for the entire exposure period. Manufacturers should be encouraged to produce equipment engineered for ease of cleaning and disinfection. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.
Pasteurization is a process developed by Louis Pasteur of heating milk, wine, or other liquids to 65–77°C (or the equivalent) for approximately 30 minutes to kill or markedly reduce the number of pathogenic and spoilage organisms other than bacterial spores. Pasteurization is not a sterilization process; its purpose is to destroy all pathogenic microorganisms. However, pasteurization does not destroy bacterial spores. The time-temperature relation for hot-water pasteurization is generally ~70°C (158°F) for 30 minutes. The water temperature and time should be monitored as part of a quality-assurance program. Pasteurization of respiratory therapy and anesthesia equipment is a recognized alternative to chemical disinfection. Pasteurization of respiratory therapy and anesthesia equipment is a recognized alternative to chemical disinfection. The efficacy of this process has been tested using an inoculum that the authors believed might simulate contamination by an infected patient. Use of a large inoculum of P. aeruginosa or Acinetobacter calcoaceticus in sets of respiratory tubing before processing demonstrated that machine-assisted chemical processing was more efficient than machine-assisted pasteurization with a disinfection failure rate of 6% and 83%, respectively. Other investigators found hot water disinfection to be effective (inactivation factor >5 log10) against multiple bacteria, including multidrug-resistant bacteria, for disinfecting reusable anesthesia or respiratory therapy equipment. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Peracetic acid is a highly biocidal oxidizer that maintains its efficacy in the presence of organic soil. Peracetic acid removes surface contaminants (primarily protein) on endoscopic tubing. An automated machine using peracetic acid to sterilize medical, surgical, and dental instruments chemically (e.g., endoscopes, arthroscopes) was introduced in 1988. This microprocessor-controlled, low-temperature sterilization method is commonly used in the United States. The sterilant, 35% peracetic acid, and an anticorrosive agent are supplied in a single-dose container. The container is punctured at the time of use, immediately prior to closing the lid and initiating the cycle. The concentrated peracetic acid is diluted to 0.2% with filtered water (0.2 μm) at a temperature of approximately 50°C. The diluted peracetic acid is circulated within the chamber of the machine and pumped through the channels of the endoscope for 12 minutes, decontaminating exterior surfaces, lumens, and accessories.

Interchangeable trays are available to permit the processing of up to three rigid endoscopes or one flexible endoscope. Connectors are available for most types of flexible endoscopes for the irrigation of all channels by directed flow. Rigid endoscopes are placed within a lidded container, and the sterilant fills the lumens either by immersion in the circulating sterilant or by use of channel connectors to direct flow into the lumen(s). The peracetic acid is discarded via the sewer and the instrument rinsed four times with filtered water. Concern has been raised that filtered water may be inadequate to maintain sterility. Limited data have shown that low-level bacterial contamination may follow the use of filtered water in an AER but no data has been published on AERs using the peracetic acid system. Clean filtered air is passed through the chamber of the machine and endoscope channels to remove excess water. As with any sterilization process, the system can only sterilize surfaces that can be contacted by the sterilant.

The manufacturers suggest the use of biological monitors (Geobacillus stearothermophilus spore strips) both at the time of installation and routinely to ensure effectiveness of the process. The manufacturer’s clip must be used to hold the strip in the designated spot in the machine as a broader clamp will not allow the sterilant to reach the spores trapped under it. One investigator reported a 3% failure rate when the appropriate clips were used to hold the spore strip within the machine. The use of biological monitors designed to monitor either steam sterilization or ETO for a liquid chemical sterilizer has been questioned for several reasons including spore wash-off from the filter paper strips which may cause less valid monitoring. The processor is equipped with a conductivity probe that will automatically abort the cycle if the buffer system is not detected in a fresh container of the peracetic acid solution. A chemical monitoring strip that detects that the active ingredient is >1500 ppm is available for routine use as an additional process control.

Microbicidal Activity. Peracetic acid will inactivate gram-positive and gram-negative bacteria, fungi, and yeasts in <5 minutes at <100 ppm. In the presence of organic matter, 200-500 ppm is required. For viruses, the dosage range is wide (12-2250 ppm), with poliovirus inactivated in yeast extract in 15 minutes with 1500 to 2250 ppm. Bacterial spores in suspension are inactivated in 15 seconds to 30 minutes with 500 to 10,000 ppm (0.05 to 1%).

Uses. This automated machine is used to chemically sterilize medical (e.g., GI endoscopes) and surgical (e.g., flexible endoscopes) instruments in the United States. Lumened endoscopes must be connected to an appropriate channel connector to ensure that the sterilant has direct contact with the contaminated lumen.

See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

PRESOAKING Presoaking instruments with an enzymatic solution is recommended to assist in loosening soil and therefore making the cleaning process easier. Presoaking instruments or devices is recommended immediately following a procedure which will prevent staining or pitting of the instrument(s). A complete rinsing should be done once presoaking is complete, removing any loosened and harmful residue. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Process challenge device (or PCD) is an item designed to simulate product to be sterilized and to constitute a defined challenge to the sterilization process and used to assess the effective performance of the process. A PCD is a challenge test pack or test tray that contains a biologic indicator, a Class 5 integrating indicator, or an enzyme-only indicator.

The size and composition of the biological indicator test pack should be standardized to create a significant challenge to air removal and sterilant penetration and to obtain interpretable results. There is a standard 16-towel pack recommended by AAMI for steam sterilization consisting of 16 clean, preconditioned, reusable huck or absorbent surgical towels each of which is approximately 16 inches by 26 inches. Each towel is folded lengthwise into thirds and then folded widthwise in the middle. One or more biological indicators are placed between the eighth and ninth towels in the approximate geometric center of the pack. When the towels are folded and placed one on top of another, to form a stack (approximately 6 inch height) it should weigh approximately 3 pounds and should have a density of approximately 11.3 pounds per cubic foot. This test pack has not gained universal use as a standard pack that simulates the actual in-use conditions of steam sterilizers.

Commercially available disposable BI test packs that have been shown to be equivalent to the AAMI 16 towel test pack also may be used. The test pack should be placed flat in an otherwise fully loaded sterilizer chamber, in the area least favorable to sterilization (i.e., the area representing the greatest challenge to the biological indicator). This area is normally in the front, bottom section of the sterilizer, near the drain. A control biological indicator from the lot used for testing should be left unexposed to the sterilant, and then incubated to verify the pre-sterilization viability of the test spores and proper incubation. The most conservative approach would be to use a control for each run; however, less frequent use may be adequate (e.g., weekly).

Instruments should be handled as though contaminated until processed through the sterilization cycle (unless the instrument has been processed with a thermal washer/disinfector that has a high-level disinfection cycle). To avoid injury from sharp instruments, personnel should wear puncture-resistant, heavy-duty utility gloves when handling or manually cleaning contaminated instruments and devices. Because splashing is likely to occur, they should also wear a facemask, eye protection or face shield, and gown or jacket. Employees should not reach into trays or containers holding sharp instruments that cannot be seen. To reduce their risk of injury, they should instead remove instruments using forceps or empty them onto a towel. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

The Smart-Read EZTest Biological Indicator Monitoring System allows an organization to release sterile product with true biological confirmation faster and easier than ever before. This unique system uses a real biological indicator (BI) -- with no added enzyme or chemical integrator -- which is incubated, evaluated, and documented in one simple, automated operation.

Quick! Detect failed-tests within 3 to 5 hours!
Relying only upon bacterial spore growth, the Smart-Read system can detect sterilization failure in as few as three to five hours, and confirm sterilization in only ten hours.

Though a highly sophisticated tool, the Smart-Well incubator is easy to configure with its simple touch-screen interface. The incubator can evaluate up to ten Smart-Read BIs independently, and contains one additional incubation cell for a positive control unit. Each BI test result is automatically documented in a user-customizable printed report, and an alarm is sounded the moment that sterilization failure is detected. The incubator also contains an NIST-traceable thermometer marked at the appropriate incubation temperature to allow an operator to quickly verify proper operation.

The Smart-Well incubator is available in a start-up kit including the incubator itself, a stylus, a report printer, a record book for storing reports, a thermometer, and all necessary cabling.

Smart-Read System Features
Fast biological results
True biological system
One BI for all processes
Easy one-step evaluation
Automatic documentation
Alarm on sterilization failure
100% Verifiable results

The Smart-Read EZTest BI ampoules are a familiar self-contained color change biological indicator (BI) specifically designed for rapid evaluation in the Smart-Well incubator. It requires no special processing and can be used in place of any existing self-contained BI. The Smart-Read BI contains spores of Geobacillus stearothermophilus and is suitable for all steam sterilization processes.

Regulated Waste is liquid or semi-liquid blood or other potentially infectious materials; contaminated items that would release blood or other potentially infectious materials in a liquid or semi-liquid state if compressed; items that are caked with dried blood or other potentially infectious materials and are capable of releasing these materials during handling; contaminated sharps; and pathological and microbiological wastes containing blood or other potentially infectious materials.

Rinsing is a must, following the initial presoaking process and then after mechanical or manual cleaning of the instrument or device. This ensures that loosened debris and residue of detergents from the cleaning process are completely removed. Tap water is acceptable for rinsing; however, for the final rinse, treated water is recommended to avoid staining, corrosion or pitting of the instrument or device.

Rinsing endoscopes:
Rinsing endoscopes and flushing channels with sterile water, filtered water, or tap water will prevent adverse effects associated with disinfectant retained in the endoscope (e.g., disinfectant-induced colitis). Items can be rinsed and flushed using sterile water after high-level disinfection to prevent contamination with organisms in tap water, such as nontuberculous mycobacteria, Legionella, or gram-negative bacilli such as Pseudomonas. Alternatively, a tap water or filtered water (0.2μ filter) rinse should be followed by an alcohol rinse and forced air drying. Forced-air drying markedly reduces bacterial contamination of stored endoscopes, most likely by removing the wet environment favorable for bacterial growth. After rinsing, items should be dried and stored (e.g., packaged) in a manner that protects them from recontamination. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Sanitizer is an agent that reduces the number of bacterial contaminants to safe levels as judged by public health requirements. Commonly used with substances applied to inanimate objects. According to the protocol for the official sanitizer test, a sanitizer is a chemical that kills 99.999% of the specific test bacteria in 30 seconds under the conditions of the test.

Shelf life of sterile items is event-related, depending on the quality of the packaging material, storage conditions, conditions during transport, and the amount it was handled. Generally, sterile items should be rotated using the “first-in, first-out” principle. See also event-related packaging.
Of all the methods available for sterilization, moist heat in the form of saturated steam under pressure is the most widely used and the most dependable. Steam sterilization is nontoxic, inexpensive, rapidly microbicidal, sporicidal, and rapidly heats and penetrates fabrics. Like all sterilization processes, steam sterilization has some deleterious effects on some materials, including corrosion and combustion of lubricants associated with dental headpieces; reduction in ability to transmit light associated with laryngoscopes; and increased hardening time with plaster-cast.

The basic principle of steam sterilization, as accomplished in an autoclave, is to expose each item to direct steam contact at the required temperature and pressure for the specified time. Thus, there are four parameters of steam sterilization: steam, pressure, temperature, and time. The ideal steam for sterilization is dry saturated steam and entrained water (dryness fraction >97%). Pressure serves as a means to obtain the high temperatures necessary to quickly kill microorganisms. Specific temperatures must be obtained to ensure the microbicidal activity. The two common steam-sterilizing temperatures are 121°C (250°F) and 132°C (270°F). These temperatures (and other high temperatures) must be maintained for a minimal time to kill microorganisms. Recognized minimum exposure periods for sterilization of wrapped healthcare supplies are 30 minutes at 121°C (250°F) in a gravity displacement sterilizer or 4 minutes at 132°C (270°C) in a prevacuum sterilizer. At constant temperatures, sterilization times vary depending on the type of item (e.g., metal versus rubber, plastic, items with lumens), whether the item is wrapped or unwrapped, and the sterilizer type. The two basic types of steam sterilizers (autoclaves) are the gravity displacement and the dynamic-air-removal sterilizers.

Weekly testing is minimum:
Steam and low temperature sterilizers (e.g., hydrogen peroxide gas plasma, peracetic acid) should be monitored at least weekly with the appropriate commercial preparation of Geobacillus stearothermophilus spores. If a sterilizer is used frequently (e.g., several loads per day), daily use of biological indicators allows earlier discovery of equipment malfunctions or procedural errors and thus minimizes the extent of patient surveillance and product recall needed in the event of a positive biological indicator. Each load should be monitored if it contains implantable objects. If feasible, implantable items should not be used until the results of spore tests are known to be negative. See also www.cdc.gov/oralhealth/infectioncontrol/faq/steri...

Sterilant is a liquid chemical germicide that destroys all forms of microbiological life, including high numbers of resistant bacterial spores. When chemicals are used to destroy all forms of microbiologic life, they can be called chemical sterilants. These same germicides used for shorter exposure periods also can be part of the disinfection process (i.e., high-level disinfection). Liquid chemical sterilants reliably produce sterility only if cleaning precedes treatment and if proper guidelines are followed regarding concentration, contact time, temperature, and pH.
The Sterilization Area is a designated area of a health-care facility designed to house sterilization equipment, such as steam ethylene oxide, hydrogen peroxide gas plasma, or ozone sterilizers. It is one of the three areas discussed below, critical to proper infection control.

Sterilization Area Guidelines:
The central processing area(s) ideally should be divided into at least three areas: decontamination, packaging, and sterilization and storage. Physical barriers should separate the decontamination area from the other sections to contain contamination on used items. In the decontamination area, reusable contaminated supplies (and possibly disposable items that are reused) are received, sorted, and decontaminated. The recommended airflow pattern should contain contaminates within the decontamination area and minimize the flow of contaminates to the clean areas. The American Institute of Architects recommends negative pressure and no fewer than six air exchanges per hour in the decontamination area (AAMI recommends 10 air changes per hour) and 10 air changes per hour with positive pressure in the sterilizer equipment room. The packaging area is for inspecting, assembling, and packaging clean, but not sterile, material. The sterile storage area should be a limited access area with a controlled temperature (may be as high as 75°F) and relative humidity (30-60% in all works areas except sterile storage, where the relative humidity should not exceed 70%). The floors and walls should be constructed of materials capable of withstanding chemical agents used for cleaning or disinfecting. Ceilings and wall surfaces should be constructed of non-shedding materials. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Any item, device, or solution is considered to be sterile when it is completely free of all living microorganisms and viruses. The definition is categorical and absolute (i.e., an item is either sterile or it is not). A sterilization procedure is one that kills all microorganisms, including high numbers of bacterial endospores. Sterilization can be accomplished either by heat, ethylene oxide gas, hydrogen peroxide gas, plasma, ozone, and radiation. From an operational standpoint, a sterilization procedure cannot be categorically defined. Rather, the procedure is defined as a process, after which the probability of a microorganism surviving on an item subjected to treatment is less than one in one million. This is referred to as the “sterility assurance level." See also recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”..
Gravity displacement steam sterilizers facilitate incoming steam which displaces residual air through a port or drain in or near the bottom (usually) of the sterilizer chamber. Typical operating temperatures are 121–123°C (250–254°F) and 132–135°C (270–275°F).

After Installation: Three consecutive BI tests must be completed using PCD’s with biological indicators, one right after the other, all showing negative results (no growth). Place the BI PCD in the area of the sterilizer least exposed to the sterilant - usually in the center near the front or near the drain of the sterilizer. Run the three consecutive BI tests in an empty chamber.

An infrared radiation prototype sterilizer was investigated and found to destroy Bacillus atrophaeus spores. Some of the possible advantages of infrared technology include short cycle time, low energy consumption, no cycle residuals, and no toxicologic or environmental effects. This may provide an alternative technology for sterilization of selected heat-resistant instruments but there are no FDA-cleared systems for use in healthcare facilities.
See Proof of Sterilization page showing detail of the three types of monitoring that is required to be done regularly, some with every sterilizer cycle. As per the FDA, “a biological sterilization process indicator is a device intended for use by a health care provider to accompany products being sterilized through a sterilization procedure and to monitor adequacy of sterilization. The device consists of a known number of microorganisms, of known resistance to the mode of sterilization, in or on a carrier and enclosed in a protective package. Subsequent growth or failure of the microorganisms to grow under suitable conditions indicates the adequacy of sterilization.” [21 CFR 880.2800(a)(1)]

Pre-vacuum steam sterilizers depend on one or more pressure and vacuum excursions at the beginning of the cycle to remove air. This method of operation results in shorter cycle times for wrapped items because of the rapid removal of air from the chamber and the load by the vacuum system and because of the usually higher operating temperature (132–135°C [270–275°F]; 141–144°C [285–291°F]). Eliminating air-pockets is critical to steam penetration in all areas of the sterilizer chamber. This type of sterilizer generally provides for shorter exposure time and accelerated drying of fabric loads by pulling a further vacuum at the end of the sterilizing cycle.

A Bowie-Dick diagnostic test is to be used before the first processed load of each day. It is a sensitive and rapid means of detecting air leaks, or inadequate air removal or inadequate steam penetration. Insufficient air removal in a pre-vacuum cycle will leave air-pockets, affecting the lethality of the sterilizer cycle, causing non-sterile instruments and/or supplies.

Steam-Flush Pressure-Pulse sterilizers use a repeated sequence consisting of a steam flush and a pressure pulse system that removes air from the sterilizing chamber and processed materials using steam at above atmospheric pressure (no vacuum is required). Like a pre-vacuum sterilizer, a steam-flush pressure-pulse sterilizer rapidly removes air from the sterilizing chamber and wrapped items; however, the system is not susceptible to air leaks because air is removed with the sterilizing chamber pressure at above atmospheric pressure. Typical operating temperatures are 121–123°C (250–254°F), 132–135°C (270–275°F), and 141–144°C (285–291°F).
A compact gravity-displacement steam sterilizer that has a chamber volume of not more than 2 cubic feet and that generates its own steam when distilled or deionized water is added. Portable (table-top) steam sterilizers are used in outpatient, dental, and rural clinics. These sterilizers are designed for small instruments, such as hypodermic syringes and needles and dental instruments. The ability of the sterilizer to reach physical parameters necessary to achieve sterilization should be monitored by mechanical, chemical, and biological indicators.
Since sterilization failure can occur (about 1% for steam sterilizers), a procedure to follow in the event of positive spore tests with steam sterilization has been provided by CDC and the Association of periOperative Registered Nurses (AORN). The 1981 CDC recommendation is that "objects, other than implantable objects, do not need to be recalled because of a single positive spore test unless the steam sterilizer or the sterilization procedure is defective." The rationale for this recommendation is that single positive spore tests in sterilizers occur sporadically.

Most “Positive Test Results” occur within 24 hours, with the sterilizer user notified immediately of the test failure. Most failed tests are caused by operator error – overloading being a common reason for failed tests. Chemical vapor and Dry Heat sterilizers are especially sensitive to overloading. Running or testing a sterilizer from a COLD start can also cause sterilizer failure. Sterilizer manufacturers recommend initially running the sterilizer EMPTY to preheat the chamber before using it and some manufacturers suggest running longer cycles if the sterilizer is used from a COLD start.

If the mechanical (e.g., time, temperature, pressure in the steam sterilizer) and chemical (internal and/or external) indicators suggest that the sterilizer was functioning properly, a single positive spore test probably does not indicate sterilizer malfunction but the spore test should be repeated immediately. If the spore tests remain positive, use of the sterilizer should be discontinued until it is serviced. Similarly, AORN states that a single positive spore test does not necessarily indicate a sterilizer failure. If the test is positive, the sterilizer should immediately be rechallenged for proper use and function. Items, other than implantable ones, do not necessarily need to be recalled unless a sterilizer malfunction is found. If a sterilizer malfunction is discovered, the items must be considered nonsterile, and the items from the suspect load(s) should be recalled, insofar as possible, and reprocessed.

A more conservative approach also has been recommended in which any positive spore test is assumed to represent sterilizer malfunction and requires that all materials processed in that sterilizer, dating from the sterilization cycle having the last negative biologic indicator to the next cycle showing satisfactory biologic indicator challenge results, must be considered nonsterile and retrieved, if possible, and reprocessed. This more conservative approach should be used for sterilization methods other than steam (e.g., ETO, hydrogen peroxide gas plasma). However, no action is necessary if there is strong evidence for the biological indicator being defective or the growth medium contained a Bacillus contaminant. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.
See Proof of Sterilization page showing detail of the three types of monitoring that is required to be done regularly, some with every sterilizer cycle. As per the FDA, “a biological sterilization process indicator is a device intended for use by a health care provider to accompany products being sterilized through a sterilization procedure and to monitor adequacy of sterilization. The device consists of a known number of microorganisms, of known resistance to the mode of sterilization, in or on a carrier and enclosed in a protective package. Subsequent growth or failure of the microorganisms to grow under suitable conditions indicates the adequacy of sterilization.” [21 CFR 880.2800(a)(1)]

When it comes to the steam sterilization of liquid media, there are a number of user concerns that are handled in various ways. Monitoring these cycles with biological indicators (BIs) and the various restrictions and cycle modifications that are done can lead to a false positive or a failed cycle. Here are only a few of the cycle modifications done or restrictions applied by users for the steam sterilization of liquid media:
User needs to keep the media flask in a container while being sterilized so the boil-over does not get all over the autoclave.
According to the manufacturer’s instructions, the user needs to sterilize the media at 121°C for 15 minutes. The user can’t find a BI that will die in this short cycle.
User can’t run a longer cycle time since the media is heat sensitive and may not promote growth if a longer cycle time is used.
User’s protocol states to run only in a 15 minute, 121°C cycle.
User has determined a cycle exposure time for a 1L flask of TSB. Now, what time should be used for a 2L flask; do I double the time?

Many unique questions arise when working with liquid loads that would never come up if the cycle was for hard goods or wrapped goods. Most of the items would not be temperature sensitive, so there would be no worry about boil-over or questioning of BI placement. Yet with liquid loads there are no concerns about pre-vacuum-air-removal or steam penetration as into a porous load.

Validating load configurations:
So, why do so many problems occur with liquid media sterilization and BI lethality? Some of the methods used to address the concerns expressed above actually can contribute to a failed cycle or a cycle where the BI is positive. This largely happens due to the fact that most of the liquid load/media cycle configurations used in many clinics, universities or hospitals were not validated. Validating a load configuration cycle provides “documented procedure for obtaining, recording and interpreting the results required to establish that a process will consistently yield product complying with predetermined specifications” (ISO/TS 11139:2006, Definitions 2, 55 2) In sterilizing media, the desired outcome is to produce media with certain qualities such as pH range, growth promotion ability and sterility.

Performing validation for liquid sterilization:
When performing a validation of a selected exposure time/temperature liquid media cycle to be used, it needs to be determined how long it takes from the start of the cycle to get the media up to 121°C. This would be recorded as the ‘come-up’ time required for that particular cycle. If this was done with 1L flasks of media, a separate validation would be needed for cycles including larger volumes (2L flasks for example). To determine ‘come-up’ time for a load of two 1L flasks of TSB, a temperature recorder could be placed into each flask of media to record the media’s temperature during the entire cycle duration. This activity would be repeated for at least two more cycles with each containing newly prepared flasks of media. The ‘come-up’ times of all three cycles should be very similar. If, for example, the ‘come-up’ times for the three cycles (to hit a temperature of 121°C) were 16 minutes, 12 minutes and 14 minutes respectively, this data could be compared, and it could then be determined that a worst-case come-up time would be 16 minutes.

There is now data that supports that, with a certain number of 1L flasks of a particular media, the temperature of the media will reach 121°C within 16 minutes of the start of the cycle. The number of flasks and the volume in each along with their position placement within the autoclave chamber should be documented and must remain the same for additional cycles used in the future unless a continued validation is performed using other placement areas or fewer flasks. It is necessary to validate a worst-case load to be able to predetermine that all other loads will also hit 121°C temperature within the specified 16 minute ‘come-up’ time.

Use a Data logger:
A very easy to use thermistor or data logger for recording the media’s temperature during a sterilization cycle can easily be placed inside the actual flask of media. By doing so, the actual temperature of what is being sterilized can be determined. Placing the data logger on a shelf inside the autoclave chamber would not show what is actually going on inside the media flask. The logger must actually be placed inside the media flask.

Running media in a longer cycle will likely not adversely affect the media and growth promotion abilities. After all, running a 35 minute cycle where it takes a 20 minute come-up time would actually be a 15 minute cycle at 121°C. If there are concerns about cycle length, run the cycle and then test the media and verify that it still performs as expected and that growth promotion has not been compromised.

Running different volumes per flask or different numbers of flasks in a cycle are situations where additional validation work would need to be done. Running 1L flasks may need a 35 minute cycle where several 2L flasks may need additional time for come-up and perhaps a 45 minute cycle or more. By using a data logger, the various exposure times needed to get differing volumes of media up to 121°C can easily be determined.

Studies in the early 1970s suggested that wrapped surgical trays remained sterile for varying periods depending on the type of material used to wrap the trays. Safe storage times for sterile packs vary with the porosity of the wrapper and storage conditions (e.g., open versus closed cabinets). Heat-sealed, plastic peel-down pouches and wrapped packs sealed in 3-mil (3/1000 inch) polyethylene overwrap have been reported to be sterile for as long as 9 months after sterilization. The 3-mil polyethylene is applied after sterilization to extend the shelf life for infrequently used items. Supplies wrapped in double-thickness muslin comprising four layers, or equivalent, remain sterile for at least 30 days. Any item that has been sterilized should not be used after the expiration date has been exceeded or if the sterilized package is wet, torn, or punctured.

Event-Related Storage:
Although some hospitals continue to date every sterilized product and use the time-related shelf-life practice, many hospitals have switched to an event-related shelf-life practice. This latter practice recognizes that the product should remain sterile until some event causes the item to become contaminated (e.g., tear in packaging, packaging becomes wet, seal is broken). Event-related factors that contribute to the contamination of a product include bioburden (i.e., the amount of contamination in the environment), air movement, traffic, location, humidity, insects, vermin, flooding, storage area space, open/closed shelving, temperature, and the properties of the wrap material. There are data that support the event-related shelf-life practice. One study examined the effect of time on the sterile integrity of paper envelopes, peel pouches, and nylon sleeves. The most important finding was the absence of a trend toward an increased rate of contamination over time for any pack when placed in covered storage. Another evaluated the effectiveness of event-related outdating by microbiologically testing sterilized items. During the 2-year study period, all of the items tested were sterile. Thus, contamination of a sterile item is event-related and the probability of contamination increases with increased handling.

Dos and Don’ts:
Following the sterilization process, medical and surgical devices must be handled using aseptic technique in order to prevent contamination. Sterile supplies should be stored far enough from the floor (8 to 10 inches), the ceiling (5 inches unless near a sprinkler head [18 inches from sprinkler head]), and the outside walls (2 inches) to allow for adequate air circulation, ease of cleaning, and compliance with local fire codes (e.g., supplies must be at least 18 inches from sprinkler heads). Medical and surgical supplies should not be stored under sinks or in other locations where they can become wet. Sterile items that become wet are considered contaminated because moisture brings with it microorganisms from the air and surfaces. Closed or covered cabinets are ideal but open shelving may be used for storage. Any package that has fallen or been dropped on the floor must be inspected for damage to the packaging and contents (if the items are breakable). If the package is heat-sealed in impervious plastic and the seal is still intact, the package should be considered not contaminated. If undamaged, items packaged in plastic need not be reprocessed. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.
Is surface disinfection necessary?
The effective use of disinfectants is part of a multi-barrier strategy to prevent health-care-associated infections. Surfaces are considered noncritical items because they contact intact skin. Use of noncritical items or contact with noncritical surfaces carries little risk of causing an infection in patients or staff. Thus, the routine use of germicidal chemicals to disinfect hospital floors and other noncritical items is controversial. A 1991 study expanded the Spaulding scheme by dividing the noncritical environmental surfaces into housekeeping surfaces and medical equipment surfaces. The classes of disinfectants used on housekeeping and medical equipment surfaces can be similar. However, the frequency of decontaminating can vary. Medical equipment surfaces (e.g., blood pressure cuffs, stethoscopes, hemodialysis machines, and X-ray machines) can become contaminated with infectious agents and contribute to the spread of health-care-associated infections. For this reason, noncritical medical equipment surfaces should be disinfected with an EPA-registered low- or intermediate-level disinfectant. Use of a disinfectant will provide antimicrobial activity that is likely to be achieved with minimal additional cost or work.
Five reasons germicidal detergent is required:
Environmental surfaces (e.g., bedside table) also could potentially contribute to cross-transmission by contamination of health-care personnel from hand contact with contaminated surfaces, medical equipment, or patients. Of the seven reasons to use a disinfectant on noncritical surfaces, five are particularly noteworthy and support the use of a germicidal detergent.
1. Hospital floors become contaminated with microorganisms from settling airborne bacteria: by contact with shoes, wheels, and other objects; and occasionally by spills. The removal of microbes is a component in controlling health-care–associated infections. In an investigation of the cleaning of hospital floors, the use of soap and water (80% reduction) was less effective in reducing the numbers of bacteria than was a phenolic disinfectant (94%–99.9% reduction). However, a few hours after floor disinfection, the bacterial count was nearly back to the pretreatment level.
2. Detergents become contaminated and result in seeding the patient’s environment with bacteria. Investigators have shown that mop water becomes increasingly dirty during cleaning and becomes contaminated if soap and water is used rather than a disinfectant. For example, in one study, bacterial contamination in soap and water without a disinfectant increased from 10 CFU/mL to 34,000 CFU/mL after cleaning a ward, whereas contamination in a disinfectant solution did not change (20 CFU/mL). Contamination of surfaces close to the patient that are frequently touched by the patient or staff (e.g., bed rails) could result in patient exposures. In a study, using of detergents on floors and patient room furniture, increased bacterial contamination of the patients’ environmental surfaces was found after cleaning (average increase = 103.6 CFU/24cm2). In addition, a P. aeruginosa outbreak was reported in a hematology-oncology unit associated with contamination of the surface cleaning equipment when non-germicidal cleaning solutions instead of disinfectants were used to decontaminate the patients’ environment and another study demonstrated the role of environmental cleaning in controlling an outbreak of Acinetobacter baumannii. Studies also have shown that, in situations where the cleaning procedure failed to eliminate contamination from the surface and the cloth is used to wipe another surface, the contamination is transferred to that surface and the hands of the person holding the cloth.
3. The CDC Isolation Guideline recommends that noncritical equipment contaminated with blood, body fluids, secretions, or excretions be cleaned and disinfected after use. The same guideline recommends that, in addition to cleaning, disinfection of the bedside equipment and environmental surfaces (e.g., bedrails, bedside tables, carts, commodes, door-knobs, and faucet handles) are indicated for certain pathogens, e.g., enterococci, which can survive in the inanimate environment for prolonged periods.
4. OSHA requires that surfaces contaminated with blood and other potentially infectious materials (e.g., amniotic, pleural fluid) be disinfected.
5. Using a single product throughout the facility can simplify both training and appropriate practice.

Clean floors with detergent/disinfectant:
Reasons also exist for using a detergent alone on floors because noncritical surfaces contribute minimally to endemic health-care-associated infections, and no differences have been found in healthcare–associated infections rates when floors are cleaned with detergent rather than disinfectant. However, these studies have been small and of short duration and suffer from low statistical power because the outcome—healthcare–associated infections—is of low frequency. The low rate of infections makes the efficacy of an intervention statistically difficult to demonstrate. Because housekeeping surfaces are associated with the lowest risk for disease transmission, some researchers have suggested that either detergents or a disinfectant/detergent could be used. No data exist that show reduced healthcare–associated infection rates with use of surface disinfection of floors, but some data demonstrate reduced microbial load associated with the use of disinfectants. Given this information; other information showing that environmental surfaces (e.g., bedside table, bed rails) close to the patient and in outpatient settings can be contaminated with epidemiologically important microbes (such as VRE and MRSA); and data showing these organisms survive on various hospital surfaces; some researchers have suggested that such surfaces should be disinfected on a regular schedule.

Spot decontaminating fabrics:
Spot decontamination on fabrics that remain in hospitals or clinic rooms while patients move in and out (e.g., privacy curtains) also should be considered. One study demonstrated the effectiveness of spraying the fabric with 3% hydrogen peroxide. Future studies should evaluate the level of contamination on noncritical environmental surfaces as a function of high and low hand contact and whether some surfaces (e.g., bed rails) near the patient with high contact frequencies require more frequent disinfection. Regardless of whether a detergent or disinfectant is used on surfaces in a health-care facility, surfaces should be cleaned routinely and when dirty or soiled to provide an aesthetically pleasing environment and to prevent potentially contaminated objects from serving as a source for health-care–associated infections. The value of designing surfaces (e.g. hexyl-polyvinylpyridine) that kill bacteria on contact or have sustained antimicrobial activity should be further evaluated.

Mops to be frequently decontaminated:
Several investigators have recognized heavy microbial contamination of wet mops and cleaning cloths and the potential for spread of such contamination. They have shown that wiping hard surfaces with contaminated cloths can contaminate hands, equipment, and other surfaces have been published that can be used to formulate effective policies for decontamination and maintenance of reusable cleaning cloths. For example, heat was the most reliable treatment of cleaning cloths as a detergent washing followed by drying at 80°C for 2 hours produced elimination of contamination. However, the dry heating process might be a fire hazard if the mop head contains petroleum-based products or lint builds up within the equipment or vent hose (American Health Care Association, personal communication, March 2003). Alternatively, immersing the cloth in hypochlorite (4,000 ppm) for 2 minutes produced no detectable surviving organisms in 10 of 13 cloths. If reusable cleaning cloths or mops are used, they should be decontaminated regularly to prevent surface contamination during cleaning with subsequent transfer of organisms from these surfaces to patients or equipment by the hands of health-care workers.

A new mop cleaning technique…
Some hospitals have begun using a new mopping technique involving microfiber materials to clean floors. Microfibers are densely constructed, polyester and polyamide (nylon) fibers, that are approximately 1/16 the thickness of a human hair. The positively charged microfibers attract dust (which has a negative charge) and are more absorbent than a conventional, cotton-loop mop. Microfiber materials also can be wet with disinfectants, such as quaternary ammonium compounds. In one study, the microfiber system tested demonstrated superior microbial removal compared with conventional string mops when used with a detergent cleaner (94% vs. 68%). The use of a disinfectant did not improve the microbial elimination demonstrated by the microfiber system (95% vs. 94%). However, use of disinfectant significantly improved microbial removal when a conventional string mop was used (95% vs. 68%) (WA Rutala, unpublished data, August 2006). The microfiber system also prevents the possibility of transferring microbes from room to room because a new microfiber pad is used in each room.

See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

Ultrasonic cleaners is a device that uses waves of acoustic energy (a process known as "cavitation") to loosen and break up debris on instruments. They are a mechanical or automatic cleaner, listed in the same family as washer-decontaminators, washer-disinfectors, and washer-sterilizers. Ultrasonic cleaning removes soil by cavitation and implosion in which waves of acoustic energy are propagated in aqueous solutions to disrupt the bonds that hold particulate matter to surfaces. Bacterial contamination can be present in used ultrasonic cleaning solutions (and other used detergent solutions) because these solutions generally do not make antibacterial label claims. Even though ultrasound alone does not significantly inactivate bacteria, sonication can act synergistically to increase the cidal efficacy of a disinfectant. Users of ultrasonic cleaners should be aware that the cleaning fluid could result in endotoxin contamination of surgical instruments, which could cause severe inflammatory reactions. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.
An unwrapped cycle (sometimes called flash sterilization) is a method for sterilizing unwrapped patient-care items for immediate use. The time required for unwrapped sterilization cycles depends on the type of sterilizer and the type of item (i.e., porous or nonporous) to be sterilized. The unwrapped cycle in tabletop sterilizers is preprogrammed by the manufacturer to a specific time and temperature setting and can include a drying phase at the end to produce a dry instrument with much of the heat dissipated. If the drying phase requirements are unclear, the operation manual or manufacturer of the sterilizer should be consulted. If the unwrapped sterilization cycle in a steam sterilizer does not include a drying phase, or has only a minimal drying phase, items retrieved from the sterilizer will be hot and wet, making aseptic transport to the point of use more difficult. For dry-heat and chemical-vapor sterilizers, a drying phase is not required.

Unwrapped sterilization should be used only under certain conditions:
1. thorough cleaning and drying of instruments precedes the unwrapped sterilization cycle
2. mechanical monitors are checked and chemical indicators used for each cycle
3. care is taken to avoid thermal injury to staff or patients
4. Items are transported aseptically to the point of use to maintain sterility. Because all implantable devices should be quarantined after sterilization until the results of biological monitoring are known, unwrapped or flash sterilization of implantable items is not recommended.

Critical instruments sterilized unwrapped should be transferred immediately by using aseptic technique, from the sterilizer to the actual point of use. Critical instruments should not be stored unwrapped. Semi-critical instruments that are sterilized unwrapped on a tray or in a container system should be used immediately or within a short time. When sterile items are open to the air, they will eventually become contaminated. Storage, even temporary, of unwrapped semi-critical instruments is discouraged because it permits exposure to dust, airborne organisms, and other unnecessary contamination before use on a patient. A carefully written protocol for minimizing the risk of contaminating unwrapped instruments should be prepared and followed. See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

A washer-disinfector is an automatic unit designed to clean and thermally disinfect instruments. The unit uses a high-temperature cycle rather than a chemical bath. This type of equipment increases productivity, improves cleaning effectiveness, and decreases worker exposure to blood and body fluids. See also Cleaning – Mechanically explaining the advantages of this type of cleaning equipment.

Wicking is the absorption of a liquid by capillary action along a thread or through the material (e.g., the enhanced penetration of liquids through undetected holes in a glove). The dry time following sterilization is important as handling processed items that are still wet increases the chance of wicking contaminants into the processed items’ packaging. Hot packs that have just been sterilized can act like wicks, absorbing moisture and possibly bacteria from hands; therefore, cooling time is a critical part of proper sterilization.



References