INFECTION CONTROL

[Drsumitra]

 What are the basic differences among the variety of chemical indicators available for use in heat sterilization?

Chemical indicators use sensitive chemicals to assess physical conditions (eg, time and temperature) during a sterilization process. Common forms are available as paper strips, labels, and steam pattern cards, which change color when certain temperature, time, and/or pressure conditions are reached during the heat cycle. Since they do not contain bacterial spores as the active agent, chemical indicators are not able to prove that sterilization has been achieved. They are valuable, however, by being able to detect certain malfunctions and can also help to identify procedural errors. Autoclave tape is the historical example of a chemical indicator. It was used for many years as visible proof that items in the chamber had been exposed to a heat sterilization process. Unfortunately, the temperature-sensitive stripes on this tape appear long before sterilizing conditions are reached in the chamber; therefore, this external marker is the least sensitive indicator for heat sterilization.
Recommendations addressing sterilization monitoring continue to include chemical monitoring of cycles. In the comprehensive 2003 CDC guidelines, the following recommendation is made: “Use mechanical, chemical, and biological monitors according to the manufacturer’s instructions to ensure the effectiveness of the sterilization process.” Each load to be sterilized should be monitored with both mechanical and chemical indicators. In a possible event where heat and pressure conditions may not be the same inside and outside the pouch, the guidelines also call for using a chemical indicator on the inside of each package in order to verify that sterilizing vapor has penetrated to reach instruments. A relatively recent innovation has made it easier to accomplish this step. Instrument pouches which contain built-in external and internal multiparameter indicators are now available. Those can provide valuable information to personnel regarding time, temperature, and sufficient exposure of processed instruments to steam.

Question 5. How applicable is “cold sterilization” in today’s world of dental infection control? 
Cold sterilization as related to dentistry refers to the practice of immersion (ie, liquid chemical) disinfection used to reprocess reusable semi-critical instruments or items for patient care. Chemical germicides used in this manner have been either glutaraldehydes, hydrogen peroxide-based, or peracetic acid solutions. There are multiple reasons why chemical immersion sterilization is no longer considered appropriate for reprocessing heat-stable medical instruments. First and foremost, virtually every available reusable dental instrument is heat-stable and should be appropriately cleaned, packaged, and sterilized between uses with a heat-based, biologically monitored process, such as a steam autoclave, dry heat sterilizer, or unsaturated chemical vapor sterilizer. The CDC refers to heat sterilization as the method of choice when sterilizing instruments and devices. If an item is heat sensitive, it is preferable to use a heat-stable alternative or disposable item. While chemical sterilants can sterilize items that would be damaged by heat, the process to accomplish this may require 6 to 10 hours of immersion. Other factors have also precluded the routine use of cold sterilization in current infection control protocols, including: (1) sterilized items must be rinsed with sterile water after removal from the solution in order to remove toxic or irritating chemical residues, and (2) a sterilization process using liquid chemicals cannot be verified by biological, spore test monitors.

Question 6. We are thinking about switching our practice to using cassettes as containers for our instruments. What factors should we consider as we discuss this major step?
The procedural shift away from ungloved healthcare personnel using small scrub brushes to routinely clean contaminated instruments at sinks has been dramatic. As more data have accumulated concerning the potential for personnel to be accidentally stuck with sharp, contaminated instruments, the use of cassettes in hospitals; dental, hygiene, and assisting schools; practices; and other healthcare facilities has increased significantly over the years. A central, precautionary reason for this is the long-standing infection control recommendation that contaminated instruments should be handled carefully, and as little as possible, in order to minimize the occurrence of accidental sharp exposures. Depending on how instruments and packages are handled and subsequently loaded into a sterilizer, there is a potential for personnel to be accidentally stuck with a sharp instrument. Using this concept as a starting point for discussion, the following should be included when discussing incorporation of cassettes into a practice setting:
1. A cassette system can substantially reduce direct handling of contaminated instruments before sterilization.
2. Different cassette sizes are available, whereby they can hold complete sets of instruments for single procedures; this eliminates the need to prepare and process multiple packages.
3. When loaded properly, it is very difficult to overload the cassette; instrument rails or racks inside the cassette are designed to hold a certain number of instruments.
4. Damage to instruments during processing in a cassette can be reduced from that noted with use of bags or pouches, because the items are held more securely in place.
5. Perforated cassettes are preferable over completely solid containers, as the latter may not allow steam or chemical vapor to reach the contents for sterilization to occur.