Procedures to Follow in the Event of a Positive Spore Test

In case of a positive spore test, the sterilizer should be removed from service. All records of physical and chemical monitoring since the last negative BI test should be reviewed. If the physical (e.g., time, temperature, and pressure) and chemical (i.e., internal or external) indicators demonstrate the sterilizer is functioning correctly, a single positive spore test probably does not indicate sterilizer malfunction, consider the possibility of operator error.

Review cleaning, packaging, loading, and spore testing procedures with all persons who work with the sterilizer. In the absence of mechanical failure of the sterilizer unit, overloading, failure to provide adequate package separation and incorrect or excessive packaging material are all common reasons for a positive BI. Using the same cycle that produced the failure, the spore test should be repeated immediately after correctly loading the sterilizer.

If physical and chemical monitoring indicates adequate processing and the repeat spore test is negative the sterilizer can be put back into service. If packaging, loading, and operating procedures have been confirmed as performed correctly but the repeat BI test is positive, the sterilizer must remain out of service until it has been inspected, repaired, and re-challenged with BI tests in three consecutive empty-chamber sterilization cycles.

A more conservative approach is to assume that a positive BI test is an indication of sterilizer malfunction. As a consequence, all items from suspect loads dating back to the last negative BI should be re-cleaned, re-wrapped, and re-sterilized.^1,2