Sterilization of the medical equipment is a worldwide problem to ensure patient safety from the spread of diseases or infections. Various situations demand answers regarding your integrity in using sterilized equipment. To make sure your answers are pleasing and supportive, first you must make yourselves sure before you satisfy others.
Although there is no way to absolutely guarantee the sterility of every instrument you process, there are methods Recommended by the Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA), which are mandated in some states, to monitor the effectiveness of the sterilization process and to identify instrument packages that have been processed through the sterilizer. These sterilization monitoring procedures help ensure patient safety.
Types of Sterilization Monitoring
Sterilization is a process designed to kill all microbes. Because we can’t actually test whether all microbes are killed during the sterilization process, the next best thing is to determine whether the process kills the most resistant microbe, which makes us to assume that all others have been killed as well.
Bacterial spores provide the foundation for the process of sterilization. They have been selected as the most resistant type of microbe, over Creutzfeldt-Jakob Disease (CJD) prion protein, and earmarked as the hallmark of resistance for three reasons:
· Bacterial spores are more resistant than all other disease-producing microbes;
· They are considered non-pathogenic;
· They are more easily handled than CJD prion protein.
The main guarantee for sterilization comes from, demonstrating the death of bacterial spores because it evaluates the process directly using live resistant microorganisms. Using bacterial spores to monitor the sterilization process is referred to as biologic monitoring (or spore-testing). The bacterial spores are referred to as biologic indicators (BIs).
Chemical indicators (CIs) that change color or form when exposed to specific high temperatures or to the sterilizing conditions within a sterilizer. This is referred to as chemical monitoring or process monitoring. Mechanical monitoring involves observing and recording the physical aspects (temperature, pressure, or time) of the cycle when the sterilizer is being operated.
Regulations and Recommendations:
Several state dental boards or state departments of health necessitate periodic spore testing of dental office sterilizers. These agencies include those in California, Florida, Indiana, Nebraska, Ohio, Oregon, and Washington. The CDC recommends spore-testing each dental office sterilizer at least weekly using a matching lot control BI along with performing a mechanical monitoring of every sterilizer load and placing a chemical indicator of every package in the load. The ADA also recommends weekly spore testing of all dental office sterilizers.
Failure to Sterilize:
Heat sterilization failure results when no direct contact occurs between the sterilizing agent (e.g., steam, dry heat, or hot chemical vapors) and all surfaces of the items being processed for the appropriate length of time. For example, improper instrument cleaning may leave debris on the instruments that can insulate underlying microbes from the heat. This inadequate cleaning cannot be detected by sterilization monitoring; therefore, cleaning must be performed very thoroughly. Sterilization monitoring usually can detect improper packaging, loading, timing, and temperature.
Biologic Monitoring:
Types of BIs: BIs contain the bacterial spores used for monitoring. The spores used are Geobacillus stearothermophilus or Bacillus subtilis. Currently, no BIs are available for routine testing of liquid chemical sterilants or disinfectants during use in the office.
Spore strips: BIs are packaged in different varieties, which are one-inch paper strips that contain one or both types of monitoring spores, and enclosed in a protective glassine envelope. After processing through the sterilizer, the strip is aseptically removed from the envelope and placed in a tube of appropriate Tryptic-soy broth medium that in turn is incubated for two to seven days at 55°C/131°F (for G. stearothermophilus) or at 37°C/98.6°F (for B. subtilis). If live bacterial spores still are present, they will grow and produce cloudiness and/or change the color of the growth medium, indicating sterilization failure. Spore strip BIs can be used to monitor all forms of heat sterilization.
Self-contained vial: Another type of BI is a self-contained vial, which comprises both a spore strip or disk and an ampoule filled with growth medium, contained in a plastic vial with a vented cap to permit entrance of the sterilizing agent into the vial. After processing through the sterilizer, either the vial is squeezed or the cap is pushed down to break the internal ampoule, which mixes the growth medium with the spores. The vial is then incubated at 55°C/131°F, and if live bacterial spores still are present, they will grow and change the color of the growth medium, indicating sterilization failure.
Using a BI: Biologic monitoring following manufacturer’s directions for spore testing. If these are not available, place a packed BI in the center of the load to be sterilized. Operate a normal cycle. Retrieve the BI and analyze it for live spores. Be sure to include a control BI, one that is not processed through the sterilizer but otherwise is handled the same way as the test BI. The control should be analyzed along with the test BI that is processed through the sterilizer. The control BI also should yield growth of the spores, thereby confirming that any live bacterial spores present could grow and would be detected.
Analyzing a BI: BIs can be analyzed with an incubator and the appropriate self-contained BIs, or by using a spore strips and broth culture system. The office can subscribe to a sterilization monitoring service that is available commercially. These services will send you the proper BIs, instructions for use, a return envelope for mailing results back to the lab, and a report of the results and will intimate if a sterilization failure is detected along with a reason causing the failure. Many services can confirm a sterilization failure by performing certain microbiological procedures regarded as too difficult to perform in the typical dental office.
Chemical Monitoring:
CI types and uses: The use of CIs that change color or physical form when exposed to certain temperatures ensure chemical monitoring. An external indicator used on the outside of every pack, to indicate that the item has at least been processed through a heat sterilizer. This distinguishes the items that have been heat-processed from those that have not and helps to prevent the accidental clinical use of unprocessed items.
These indicators do not prove whether sterilization has been achieved or even that a complete sterilization cycle has occurred. A sterilizer could heat up to the proper temperature, thereby changing the chemical indicator, and then immediately malfunction. Thus, CIs are commonly called process indicators. CI, an integrated indicator, changes color or form more slowly, and responds to a combination of time and temperature or to a process involving time, temperature, and the presence of steam. Integrated indicators commonly are used on the inside of every pack to ensure that the instruments inside the packaging material all have been exposed to sterilizing conditions.
Analysis of CIs: One helpful aspect of chemical monitoring is that the results are available immediately, either as soon as the package is removed from the sterilizer or right after the package is opened. This is unlike biologic monitoring, which requires two to seven days of incubation before results are known.
Mechanical Monitoring:
Observe the machine’s dials and gauges and listen as it functions to make sure it sounds normal. Be watchful and wary during sterilizer operation. Although some sterilizers have recording devices that document these physical parameters of time and temperature for each cycle, handwritten records of the date, run number, time, temperature, and pressure will suffice.
Sterilization failure: Now what?
Be prepared for sterilization failure. In the case of a positive spore test or if the CIs did not properly change color, take the sterilizer out of service and review your office procedures in packaging, loading, and sterilizer operation. Investigating such a failure takes time, so have a back-up sterilizer ready to run while the office analyzes the failed process.
If the sterilizer itself is deemed faulty, be aware that any items processed through the sterilizer may not be sterile. Review chemical and mechanical monitoring results to help determine when the problem may have occurred. Retrieve any items from suspect loads, and re-package and re-sterilize these items in a properly working sterilizer. Repeat the spore test in the suspect sterilizer, using proper sterilization and monitoring procedures; be sure to include chemical indicators in the repeat run. If this spore test’s results read negative and the CIs change appropriately, you may return the sterilizer to service.
If the repeat spore test is positive or the CIs do not properly change, and you have confirmed that the packaging, loading, and operating procedures were performed correctly, contact your sterilizer repair service for unit repair or replacement. The unit should be spore-tested under normal operating procedures and achieve a negative result before either a repaired or a new sterilizer is placed into service.
Ensure safety:
When it comes to instrument processing and sterilization, use all three methods of monitoring—mechanical, chemical, and biologic—to help ensure patient safety. Mechanically monitor each sterilizer load and chemically monitor each package in each load. Biologically monitor every sterilizer at least once a week. Be sure to keep accurate records on all monitoring.
Of the three methods, biologic monitoring is regarded as the most valid for monitoring the sterilization process, for it uses live, highly resistant bacterial spores. Chemical monitoring uses heat-sensitive or heat-time-steam-sensitive chemicals that change color and may help to immediately detect certain sterilizer malfunctions and help to earmark procedural problems.
The use of mechanical monitoring by observing the time, temperature and pressure of sterilizer cycles may provide early detection of a mechanical problem. Keep in mind that effective sterilization helps you reach the ultimate goal of proper instrument processing—delivering sterile instruments to chair side.