Infection Control Exam Sterilization Procedures
Sterilization Procedures Discuss the use of flash sterilization.
Flash sterilization is the sterilization of unwrapped items at relative short exposure times. It is not recommended by the CDC for routine procedures but can be used in emergency situations requiring shot turn around times. For example, if the dentist drops a critical instrument but still sterilized unwrapped, they must be handled aseptically afterwards at all points from removal from the sterilizer to patient care use. For example, sterile tongs and transport containers should be used. Procedures for flash sterilization and transport should be carefully outlined in writing, and monitoring practices should be in place.
Sterilization Procedures Discuss proper handling of instrument packages once they have been sterilized.
Instrument packages that have been sterilized must be dried and cooled before use. Most steam sterilizers have some type of incorporated drying cycle, and unsaturated chemical vapor and dry heat sterilizers generate packages that are dry at the end. The drying prevents wicking, the drawing in of microbes through wet wrapping. The packages will be warm and should be cooled gradually. Sterile packages should be stored in enclosed cabinets in dry, relatively low dust areas and away from water sources. Instruments sterilized in FDA-approved packaging should be sterile at least 6 months if stored properly but a shorter turnaround time is suggested. Instruments flash sterilized unwrapped have no storage life. It is suggested. Instruments flash sterilized unwrapped have no storage life. It is suggested that sterile instrument packages should be checked for intactness before opening. They should be opened with clean, ungloved hands after seating the patient. If rearrangement of instruments is needed at that point, sterile tongs should be used.
Sterilization Procedures Discuss ways to protect dental instruments for reuse.
One of the biggest concerns regarding protection of dental instruments is prevention of corrosion. Stainless steel instruments do not corrode significantly when in contact with moisture and heat, but those containing carbon steel do have this problem. Measures to reduce corrosion include cleaning as promptly as possible, avoiding long storage in water or chloride solutions, use of cleaning solutions specifically designed for cleaning the instruments, and adequate rinsing after cleaning. There are rust inhibitors available that can be used on carbon steel instruments before steam sterilization, and alternatively they can be processed using a dry heat or unsaturated chemical vapor sterilizer. For the latter methods, drying the items prior to sterilization also retards corrosion. A general protection method is the avoidance of contact between various instruments during cleaning.
Sterilization Procedures Discuss methods of packaging instruments for heat sterilization.
After presoaking, precleaning, and procedures such as drying to reduce instrument damage, the instruments are packaged for sterilization. All instrument packaging is regulated. Packaged instruments are medical devices and packaging must be FDA-approved. Instruments that are to be heat sterilizard in a steam autoclave can be packaged in paper wrap and sealed with autoclave tape, placed within special nylon plastic tubing and heat sealed or taped, or put in self-sealing peel pouches with paper and plastic sides. If functional groups of instruments are being sterilized, the whole cassette can be wrapped. Heat sterilization precludes use of closed containers, cloth and certain plastics. The envelope wrapping technique is often suggested if heavy paper is used. The instruments are placed in the center of the paper diagonal to the edges and an envelope is created by folding up the bottom, then each side, and finally a top flap followed by sealing with autoclave tape (a mechanical monitor). All packages should have some form of monitoring included (discussed further on another card.
Sterilization Procedures Discuss the appropriate times to do spore testing of small office sterilizers and the rationale behind each.
Biological monitoring or spore testing of small office sterilizers used in a dent office can be done in-house or through a mail-in monitoring service. In office monitoring is more cumbersome and requires purchase of a number of supplies. Spore testing should be done once a week to confirm that the sterilizer is functioning and being used properly. It should also be performed anytime a new type of packaging material or tray is employed to make sure the sterilizing agent is contacting the surface of instruments. It is also appropriate when initiating use of a new sterilizer for familiarization purposes and initially after a device is repaired to make sure it is functioning correctly. If some changes is instituted in the sterilizing procedure, spore testing should be done. Biological monitoring should be done every time sterilization is used for implantable devices to ensure that microorganisms are not implanted; in this case the device should not be installed until results are known. Lastly, spore testing should be done after sterilization runs done by employees undergoing training to make sure they are doing them properly.
Sterilization Procedures Discuss chemical monitoring of the sterilization process.
Chemical monitors are indicators that change color or transform physically during the sterilization process. Externally-applied autoclave tape and special markings on certain pouches and bags are examples of chemical monitors that change color once a certain high temperature has been reached. Autoclave tape develops dark stripes and other types of chemical monitors have distinct color changes within a certain region. There are also chemical monitors called integrated indicators that are designed to be put inside every wrapped instrument package, where they undergo color changes during sterilization if these internal indicators are not visible, an external chemical monitor such as autoclave tape should also be applied. After the sterilization process, if external chemical monitors have not changed color indicating a sterilization failure, the processed instruments should not be used and spore testing should be done. Processed instruments should also not be used if after opening it is clear that an internal chemical monitor has not changed color. When internal indicators have not changed color, either no sterilization was performed or the sterilizing agent did not get through the packaging for some reason.
Sterilization Procedures Explain disinfection.
Disinfection is the use of chemical agents called disinfectants that can destroy most microorganisms but not the more resistant bacteria or fungal spores. Disinfectants are generally used at room temperature to reduce microbial load on surfaces. Chemicals that are used for disinfection include agents such as iodophors, phenolics, sodium hypochlorite, alcohol, and quaternary ammonium compounds. Some high-level disinfectants such as glutaraldehyde can also be used for liquid chemical sterilization if used for prolonged periods. Unlike some methods of sterilization, there is no way of monitoring the effectiveness of surface disinfection.
Sterilization Procedures Discuss dry heat sterilization of instruments.
Dry heat sterilization heat air to kill microorganisms without generation of steam. This necessitates higher temperatures than other sterilization methods. The biggest advantage of dry heat sterilizers is that they do not corrode instruments. Static air or oven-type dry heat sterilizers have heating coils that generate heat inside through natural convection which is then transmitted to the instruments. Once an internal temperature of 320°F (160°C) is achieved, this temperature is maintained for 1 to 2 hours for sterilization. Other dry heat sterilizers use forced air circulation or rapid heat transfer. These sterilizers begin their sterilization cycle once 375°F or 190°C is attained. Wrapped or unwrapped instruments should be kept at this temperature for 12 or 6 minutes respectively. Whichever type is utilized, the chamber door must remain closed throughout sterilization to maintain the desired temperature. Timing outlines should be adhered to, and routine spore testing with Bacillus atrophaeus is essential.
Sterilization Procedures Discuss less common sterilization methods that might be used.
Ethylene oxide gas will kill microorganisms at low temperatures (~120°F) and is useful for sterilizing plastic and rubber items. Its drawbacks are long sterilization times (up to 12 hours), the need for lengthy post sterilization aeration to get rid of gas molecules, and potential toxicity. Wet items cannot be sterilized with this method. A new but expensive technique that also uses low temperatures utilizes vaporized hydrogen peroxide gas plasma. So-called "bead sterilizers" have been used in the past but are not really recommended as they are difficult to monitor and deal with aseptically. This type of sterilization involves glass beads heated to about 450°F. Instruments to be sterilized are briefly plunged into the glass beads. Hot mineral oil baths are another antiquated and unacceptable method of sterilization.
Sterilization Procedures Briefly summarize how to sterilize heat-labile items.
Heat-labile items that do not penetrate tissue (such as rubber dam frames and x-ray collimators) must be sterilized using a liquid sterilant/high-level disinfectant. For example, 2 to 3.4% glutaraldehyde or 7% hydrogen peroxide may be used as a sterilant/disinfectant. Gloves and other protective equipment should be worn throughout involved procedures. Sterilants solutions often have to be prepared as indicated by the manufacturer before use and may have a restricted life. These solutions should be clearly marked with chemical name, date, and other useful information and kept in a covered container. They should also be tested for concentration periodically using a chemical test kit and replaced if necessary. The items to be sterilized should be precleaned, rinsed and dried initially. Then they are placed into the liquid sterilant using a perforated try or tongs, taking care that they are completely immersed in the solution The appropriate immersion time should be indicated on the product label. Using aseptic technique (usually sterile tongs), the sterilized items are rinsed with sterile water, dried, and placed in a sterile container until use.
Sterilization Procedures Discuss unsaturated chemical vapor sterilization instruments.
In unsaturated chemical vapor sterilization, a chemical solution with the active ingredient of 0.23% formaldehyde and other organic compounds is heated in a closed chamber along with the instruments. Once a temperature of about 270°F (132°C) and vaporization of the chemical solution is achieved during this heat-up cycle, the sterilizing cycle is initiated and maintained for 20 minutes. These phases are followed by a depressurization and an optional purge cycle. A drying phase is not needed because the chemical solution vaporizes. Another advantage of this method is that instrument will not corrode because the solution contains very little water. A disadvantages is that it is crucial to have adequate ventilation because of chemical vapor smells, which can be alleviated through use of a purge system.
Sterilization Procedures Discuss methods of packaging instruments to be sterilized with dry heat or unsaturated chemicals.
Instruments that are to be put in dry heat sterilizers can be wrapped in paper wrap, certain nylon plastic tubing, closed containers, wrappers made for perforated cassettes, or aluminum foil. Aluminum foil is not ideal as it can tear or be easily perforated, and if closed containers are used, a biological indicator must be included. Many plastic types of wrapping are unsuitable because they may char or melt. The appropriate types of wrapping for use with an unsaturated chemical sterilizer are paper wrap, paper and plastic peel pouches, and appropriately wrapped perforated cassettes. Closed containers cannot be used for chemical sterilization. Cloth wrapping is unsuitable as it absorbs chemical vapor, and certain plastic are also unsuitable as they can melt. Whatever sterilization process is to be used, the wrapping material must be FDA-approved.
Sterilization Procedures Explain what sterility assurance entails
Sterility assurance is the practice of measures to ensure that sterility of items processed through a sterilizer is achieved and maintained. These measures include suitable instrument packaging, the sterilization process, proper storage of sterilized packages, and use of monitoring procedures. A sterility assurance program can be instituted by selecting the correct procedure(s), developing a detailed written protocol for performance, including these protocols in employee training, and setting up biologic, chemical and mechanical monitoring systems of the performance. It is also advisable to set up a system of measuring results.
Sterilization Procedures Discuss methods of precleaning contaminated instruments prior to sterilization.
Most contaminated instruments are presoaked in water, detergent, or enzyme solution directly in the basket in which they will be precleaned. This step removes gross debris. The subsequent precleaning step reduces the biodurden of microbes and organic components. The FDA approves use of ultrasonic cleaners or instrument washers for precleaning. Manual scrubbing of instruments at this juncture is not recommended. Ultrasonic cleaners utilize ultrasonic energy, high frequency sound waves, to remove debris. Loose instruments are placed in removable cleaning baskets or cassette racks in the cleaner, covered, and cleaned per manufacturer's instructions. There should be enough cleaning solution to cover the instruments during the process. The cleaning time is variable depending on factors like the types of instruments being cleaned and what is on them; it usually varies from 4 to 16 minutes. Afterwards, the basket or cassette rack is taken out and rinsed with tap water. Cleaning solution should be drained or disposed of daily. In larger settings, FDA-regulated instrument washers are used for precleaning; they come in bench top, floor unit and large production versions. Utility gloves and personal protective equipment should always be worn.
Sterilization Procedures Explain what biological monitoring involves.
Since it is impossible to directly test each piece of sterilized equipment for effectiveness of sterilization, the process must be monitored by biological, chemical, and/or mechanical monitoring. Biological monitoring, also termed spore testing, basically involves putting very resistant bacteria spores into the system and later checking to see whether they have been killed. The biological indicators (BIs) generally used are strips (or vials for steam sterilization) of spores of Geobacillus stearothermophilus for steam autoclaves and unsaturated chemical vapor chambers, and bacillus atrophaeus spore strips in dry heat or ethylene oxide sterilizers. After each sterilization, the BIs are removed aseptically and incubated in culture medium for 2 to 7 days at 55°F for G. stearothermophilus or 37°F for B. atrophaeus. The growth medium will turn cloudy or change color if spores are present. Vial-type indicators are squeezed or have caps that are pushed down to break an internal ampule and subsequently incubated at 55°F. Spore testing should be performed minimally once a week. A control strip or vial that was not put in the sterilizer should be cultured similarly for reference.
Sterilization Procedures Discuss the types of steam sterilizers and the conditions for complete sterilization.
Steam sterilizers kill microorganisms by applying steam under pressure. High temperature is achieved quickly using steam. The three basic types of steam sterilizers or autoclaves are gravity displacement, vacuum pump (type B), and positive steam flush/pressure pulse. Each forces air out before generating steam. Mechanisms of air removal are via a drain for gravity displacement, a vacuum for type B, and repeated cycles of steam flushes and pressure pulses for the method by the same name. Standard sterilizing conditions are for 20 to 30 minutes once a steam temperature of 250°F (121.1°C) is achieved, but shorter times at a higher temperature of 273°F (134°C) are also used. Standard small office sterilizers usually have heat-up, sterilizing, depressurization, and drying cycles. Preset sterilizing cycles of 15 or 30 minutes at 250°For 3 or 10 minutes at 273°F are commonly used. Wrapped packages should be inserted on their edge without stacking and unloaded only after drying to avoid wicking, the drawing in of external microbes. Flash sterilization (described elsewhere) should be done only in emergency situations for 3 to 10 minutes at 273°F. Hospital-type sterilizers are basically larger versions directly connected to a steam line.
Sterilization Procedures Discuss reasons for sterilization failure.
Sterilization failure is an extremely rare occurrence if sterilization is performed correctly. Sterilization failure can be due to improper precleaning or packaging of the instruments, use of an unacceptable method of sterilization, or improper loading, timing or temperature setting related to the sterilization process. Instruments that are not precleaned properly can still have attached debris that prevents contact between the item and the sterilizing agent. If the wrong packaging material is used, the sterilizing agent might be prevented from contact with the contaminated item or the packaging material might melt. Contact with the sterilizing agent can also be retarded if too much packaging or a closed container is used. Cloth wraps are unacceptable is chemical vapor sterilizers as they absorb chemicals. Method problems are generally related to use of sterilization for heat-sensitive items like plastic or attempts to use chemical vapors or dry heat to sterilize things in solution or water. Overloading or failing to separate packages can impede penetration of the sterilizing agent. Insufficient heat or sterilization time will not kill all microorganisms and/or spores.
Sterilization Procedures Explain sterilization.
Sterilization is a means of killing all microorganisms present. There are three methods of sterilization applicable to dentistry. These are sterilization using head, gas, or liquid chemicals. Heat sterilization is performed in a steam sterilizer or autoclave at 250 to 375 degrees Fahrenheit. Gas sterilizers generally use ethylene oxide at a lower temperature of 72 to 140°F but for a longer time period; they are uncommon in dental settings. Articles that will not withstand heat are usually subjected to liquid chemical sterilization at room temperature. Liquid chemical sterilants, also classified as high-level disinfectants, include agents such as glutaraldehyde and hydrogen peroxide often in combination. Heat sterilization is the most effective method because if the sterilizer is working properly it can kill more resistant microorganisms such as Mycobacterium species as well as highly-resistant protein products such as bacterial endospores and fungal spores. The standard for biological monitoring of a sterilizer is whether it in fact can kill bacterial endospores. At present it is difficult to monitor effectiveness of liquid chemical sterilization.
Sterilization Procedures Discuss the components of a complete sterilization monitoring program.
The CDC advocates that dental offices include as part of a complete sterilization monitoring program a chemical indicator on the inside of every package. If the internal chemical indicator is not visible, an external chemical indicator should be placed as well on every package to be processed. Every cycle should also undergo mechanical monitoring, which entails observation of all gauges, displays, and readouts. In addition, biologic monitoring in the form of spore testing appropriate for the type of sterilizer utilized should be carried out at least weekly. Documentation of each type of monitoring is essential for sterility assurance and should be kept in case problems are identified.
Sterilization Procedures Discuss the CDC categorization of patient care items.
The Center for Disease Control and Prevention (CDC) places patient care items into one of three categories in terms of how they must be processed after contamination. The first category is critical items, which are items that pierce soft tissue touch bone, or come in contact with the bloodstream or normally sterile oral tissue. These include items such as scalers, blades, dental burs, and surgical instruments. The CDC mandates critical items must be cleaned and then sterilized using heat. Semicritical patient care items are those that come in contact with mucous membranes but do not penetrate them, or that come in contact with bone, the bloodstream, or normally sterile oral tissue. Semicritical items include things like the mouth mirror, reusable impression trays, and handpieces. They should be processed just like critical items, using cleaning followed by heat sterilization unless they are heat-sensitive. With heat-sensitive items, a high-level disinfectant can be used. Lastly, noncritical items are those that only come in contact with intact skin, such as a blood pressure cuff or stethoscope. These items should be cleaned and disinfected using a low-or intermediate-level disinfectant, depending on whether there is no or some visible blood on them.
Sterilization Procedures Discuss the aluminum foil test.
The aluminum foil test is a method of evaluating the functionality of an ultrasoniuc cleaning unit. A piece of aluminum foil about 1 inch shorter than the length of the chamber by about 1 inch longer than its depth is cut. The foil dipped vertically into the chamber filled with solution without touching the bottom. The unit is turned on for 20 seconds. The foil is taken out and scrutinized for pebbling or small indentations on the foil. If the ultrasonic unit is operating properly, this pebbling will be uniformly found on the previously submerged portion of the foil. If there are areas with no pebbling the unit may need to be serviced.
Sterilization Procedures Outline the process of biologic monitoring or spore testing in a dental office.
The appropriate biological indicator should be inserted into a suitable type of wrapping, placed into the center of a load to be processed in the sterilizer, and treated in exactly the same manner as containing the biological indicator should be clearly marked if necessary, and if a spore strip is utilized, it should not be removed from its blue envelope. The center of the load is usually appropriate for the BI as that is the most difficult area for the sterilization to reach after processing, the test date, sterilizer type, time and temperature used, type of monitor, and operator should be documented. The biological indicator is removed from the sterilizer. It and an unprocessed control indicator are sent to the sterilization monitoring service or incubated and observed for spores in-house to make certain of test reliability and sterilization success. Monitoring results should be recorded and maintained. If a sterilization failure is indicated, the sterilizer must be removed from service and spore testing done under controlled conditions.
Sterilization Procedures Discuss follow-up procedures in the event of a sterilization failure.
The first step in the event of a sterilization failure is the removal of that sterilizer from service and complete re-processing of any instruments sterilized since the previous spore test. Sterilization procedures then need to be scrutinized. This involves review of all chemical monitoring records since the most recent negative spore test. Loading and operating methods should be reviewed to determine if any changes had been made, if anything had been done involved. Any problems identified should be addressed and the sterilizer retested afterwards using the same conditions as during the sterilization failure. All 3 types of monitoring should be included during this cycle and all gauges and readouts should be observed during the process. If biologic and chemical monitoring tests are negative, the sterilizer can be returned to service at this point, but if the spore test is positive the machine must be repaired or replaced. Later a new or repaired sterilizer must be spore tested three times with negative results before any instruments can be sterilized in it.
Sterilization Procedures Discuss handpiece asepsis.
The inside and outside of handpieces and their attachments must be cleaned and sterilized between patients as they may contain patient materials. While still attached to the hose after patient treatment, the handpiece should be wiped free of visible debris. High-speed handpieces should also be flushed 20 to 30 seconds into the vacuum line or some receptacle like the sink or a container. The handpiece is then removed from the hose and externally cleaned, rinsed and dried. Then the internal parts should be cleaned and lubricated per manufacturer's instructions. The handpiece is reconnected to the air/water system for flushing the excess out as before. surplus lubricant on the outside is wiped off. At that point, the handpiece should be packaged and sterilized as directed by the manufacturer. Note that some handpieces cannot withstand extremely high temperatures such as those used in dry heat sterilizers. The handpiece is then dried, cooled, and retained in the packaging until ready for use. Some handpieces need post-sterilization lubrication; if so, using aseptic technique the bag is opened, lubricant is squirted into it, the hose is attached and excess lubricant is extruded.
Sterilization Procedures Discuss the design of an instrument processing area.
The instrument processing area should be distinct from other spaces, yet centrally located. Ideally it should be in a separate room or rooms with no outside doors or windows to let in dust and good ventilation. There should be three separate areas for decontamination, packaging, and sterilizing and storage. There should be a logical work flow within each zone and between zones. Each area should be clearly marked. The decontamination area should be equipped with personal protective equipment, a sharps container, tongs, a sink and handwashing dispenser, an ultra sonic cleaner and detergent, waste containers for biohazardous materials and nonregulated waste, facilities to prepare handpieces (cleaners, lubricants, air and vacuum lines for flushing), and a drainer. The packaging area should be equipped with rust inhibitors, replacement parts, biologic and chemical indicators, packaging materials, a heat sealer, and autoclave tape. The sterilizing should contain the sterilizer(s), appropriate solutions (water, glutaraldehyde, etc.), a glutaraldehyde monitor if used, lubricant for the handpiece, air and vacuum lines for flushing excess lubricant, and incubator for culturing spore strips/vials, and an enclosed storage space.
Sterilization Procedures Briefly summarize the seven steps involved in processing instruments.
There are seven steps involved in preparing contaminated instruments to be reused. They are as follows: Step 1 - brief holding or presoaking of the contaminated instruments in detergent, water, or enzyme solution to keep attached debris from drying Step 2 - precleaning to reduce the bioburden, surface microbial or organic material, before decontamination, generally through use of an ultrasonic cleaner Step 3 - corrosion control measures, drying and/or ;lubrication to moderate potential damage to the instruments Step 4 - packaging of the instruments to preserve sterility after sterilization Step 5 - sterilization or disinfection with a high-level agent to destroy all microorganisms present Step 6 - biological, chemical and/or mechanical monitoring of the sterilization process to ensure the sterilizer is performing properly Step 7 - correct handling of the processed instruments, including procedures like drying and cooling and proper techniques for storage, distribution, and opening of the instrument packages
