Remember, for heat sterilization to occur, a sterilizing agent such as steam, dry heat, or hot chemical vapor must exist at a minimum temperature, must directly contact the surface of the item being processed, and must have a minimum contact time with those items. Any aberrations can result in sterilization failure.

By the way, this particular interference caused by inadequate cleaning cannot be detected using the standard sterilization monitoring methods—mechanical, chemical, or biological procedures. In other words, although all monitors could indicate that sterilizing conditions have been met, any improperly cleaned instruments still could contain live microbes. Thus, cleaning must not only be thorough, it also must involve proper procedures.

CHAMBER MAINTENANCE It is important to clean the interior of a steam sterilizer chamber and its various drains and ports at least once per week to prevent debris from accumulating on processed items.

Therefore, FDA-cleared sterilization packaging materials, including paper bags, nylon-plastic tubing, paper/plastic peel pouches, and sterilization wrap, must be used as directed by manufacturers to ensure sterility. What’s more, packaging materials must be used only in the specific type of sterilizer they’re made for. For example, using paper/plastic peel pouches (normally used in a steam autoclave1) in a dry heat sterilizer can cause the seal between the paper and plastic to separate.
Also, non-FDA-cleared packaging material such as plastic freezer bags may not allow the sterilizing agent to penetrate through to the items inside. In fact, any non-FDA-cleared closed container, including metal boxes or glass tubes with tops, will prevent steam and hot chemical vapors from reaching the items inside. But being too open is not always ideal, either. Using woven cloth as a wrapping material may allow penetration of a sterilizing agent, but it does not maintain an inner sterile environment, because the loose weave does not prevent the entrance of microbes from the surrounding atmosphere, spatter, or dust.
In addition, the packaging procedure used must follow manufacturer’s directions. For example, using too many layers of wrapping material can delay sufficient penetration of the sterilizing agent.
Use of chemical and biological monitoring can detect many problems with packaging materials and procedures. As discussed in last month’s Infection Control Report, sterilization indicators should be placed inside packages to measure sterilizing agents’ penetration.2

USE IT, don't lose it! The sterilizer Operator’s Manual offers vital information on unit maintenance and monitoring.

Using chemical and biological monitoring methods can indirectly detect problems with sterilizer loading because these monitoring indicators are placed inside of packages. All packages loaded should include internal chemical indicators. Placement of a package containing a biological indicator should follow the sterilizer manufacturer’s directions, which frequently state this package should be placed near the drain, where the temperature may be the lowest. Another way to assess proper loading is to place the package containing the indicator in the center of the load.

Also, mechanical, chemical, and biological monitoring methods can detect potential problems with sterilizing conditions, but they cannot determine whether the correct cycle has been reselected for the particular items processed.2

Clean and dry The sterilizer’s air filter (at the right of red arrow) prevents package recontamination.

One steam sterilizer manufacturer offers the following maintenance schedule: