Since sterilization failure can occur (about 1% for steam sterilizers), a procedure to follow in the event of positive spore tests with steam sterilization has been provided by CDC and the Association of periOperative Registered Nurses (AORN).  The 1981 CDC recommendation is that "objects, other than implantable objects, do not need to be recalled because of a single positive spore test unless the steam sterilizer or the sterilization procedure is defective." The rationale for this recommendation is that single positive spore tests in sterilizers occur sporadically. 

Most “Positive Test Results” occur within 24 hours, with the sterilizer user notified immediately of the test failure.  Most failed tests are caused by operator error – overloading being a common reason for failed tests.  Chemical vapor and Dry Heat sterilizers are especially sensitive to overloading.  Running or testing a sterilizer from a COLD start can also cause sterilizer failure.  Sterilizer manufacturers recommend initially running the sterilizer EMPTY to preheat the chamber before using it and some manufacturers suggest running longer cycles if the sterilizer is used from a COLD start.

If the mechanical (e.g., time, temperature, pressure in the steam sterilizer) and chemical (internal and/or external) indicators suggest that the sterilizer was functioning properly, a single positive spore test probably does not indicate sterilizer malfunction but the spore test should be repeated immediately.  If the spore tests remain positive, use of the sterilizer should be discontinued until it is serviced.  Similarly, AORN states that a single positive spore test does not necessarily indicate a sterilizer failure.  If the test is positive, the sterilizer should immediately be rechallenged for proper use and function.  Items, other than implantable ones, do not necessarily need to be recalled unless a sterilizer malfunction is found.  If a sterilizer malfunction is discovered, the items must be considered nonsterile, and the items from the suspect load(s) should be recalled, insofar as possible, and reprocessed.  

A more conservative approach also has been recommended in which any positive spore test is assumed to represent sterilizer malfunction and requires that all materials processed in that sterilizer, dating from the sterilization cycle having the last negative biologic indicator to the next cycle showing satisfactory biologic indicator challenge results, must be considered nonsterile and retrieved, if possible, and reprocessed.  This more conservative approach should be used for sterilization methods other than steam (e.g., ETO, hydrogen peroxide gas plasma).  However, no action is necessary if there is strong evidence for the biological indicator being defective or the growth medium contained a Bacillus contaminant.  See the complete recommendations on sterilizer and disinfection at www.cdc.gov “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”.

DID YOU KNOW?

§       Autoclave Testing Service, Inc. is one of the first companies nationwide to offer a Mail-In sterilizer monitoring service using biological indicators.  Serving the healthcare industry throughout the United States and Canada since 1986, we have thousands of satisfied customers.

§       We have on-line test results allowing you to access your results at your convenience!  Your Sterilizer Test Report (STR) is posted on-line upon completion of culturing, offering minimum turn-around time.

§       We have 24-hour test results for Steam sterilizers!

§       We have a comprehensive Glossary of Terms related to the sterile processing area (scroll below to view the Glossary).  This is invaluable information, assisting you with this important area of your facility.

ATS, Inc. now stocks sterilization pouches, sterilizer cleaners, chemical indicator products, sterilizers (new and used), ultrasonic cleaners, water distillers, and more!  (see Supplies).