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5/31/2018 » 6/3/2018
2018 OSAP Annual Conference

FAQ - Sterilization - 2016
FAQ - Sterilization - 2016



My question is with regards to "what is the best location for placing an in-house" incubator for monitoring biological indicators (control and test indicators)? Could you please provide some professional resources (CDC, APIC, etc.) with their recommendations? Chris Miller's "Infection Control and Management of Hazardous Materials for the Dental Team, 5th Edition (2014)" recommends placement of the incubator in the same room as the sterilizers. My question, does incubating "control" vials containing unsterilized spores pose any risk for contamination of a "clean" area? 


In general, the 2003 CDC guidelines for infection control in dentistry states the following regarding biological indicators:

Biological indicators (BIs) (i.e., spore tests) are the most accepted method for monitoring the sterilization process (278,279) because they assess it directly by killing known highly resistant microorganisms (e.g., Geobacillus or Bacillus species), rather than merely testing the physical and chemical conditions necessary for sterilization (243). Because spores used in BIs are more resistant and present in greater numbers than the common microbial contaminants found on patient-care equipment, an inactivated BI indicates other potential pathogens in the load have been killed (280).

Correct functioning of sterilization cycles should be verified for each sterilizer by the periodic use (at least weekly) of BIs (2,9,134,243,278,279). Every load containing implantable devices should be monitored with such indicators (248), and the items quarantined until BI results are known. However, in an emergency, placing implantable items in quarantine until spore tests are known to be negative might be impossible.

Manufacturer’s directions should determine the placement and location of BI in the sterilizer. A control BI, from the same lot as the test indicator and not processed through the sterilizer, should be incubated with the test BI; the control BI should yield positive results for bacterial growth.

In-office biological monitoring is available; mail-in sterilization monitoring services (e.g., from private companies or dental schools) can also be used to test both the BI and the control. Although some DHCP have expressed concern that delays caused by mailing specimens might cause false-negatives, studies have determined that mail delays have no substantial effect on final test results (281,282). 1

Ask OSAP is attaching information from Infection Control and Management of Hazardous Materials for the Dental Team. As you noted, this publication does reference the location of the BI incubator. Figure 12-22 places the incubator separately at the very end of the work flow process and on the sterilization side. This comes after closed storage of sterile packages and closed storage of clean disposable items. 2

It is recommended that you consult with the product instruction manual or contact the manufacturer of your product directly in order to obtain further information on the usage of this product, as well as the level of potential pathogenicity of the test spores. The manufacturer’s validated  instructions for use (IFU) may contain further relevant information. There may also be separate laws in your state governing this matter, and you may wish to contact your state public health agency (i.e., state health department) for further information. Requirements can vary by state.


1)     Kohn WG, Collins AS, Cleveland JL, Harte JA, Eklund KJ, Malvitz DM, Centers for Disease Control and Prevention (CDC). Guidelines for infection control in dental health-care settings—2003. MMWR Recomm Rep 2003;52(RR-17):1-61.    Accessed on May 23, 2016.

2)     Miller CH. Infection Control and Management of Hazardous Materials for the Dental Team, 5th edition. Elsevier/Mosby Publishers. Pages 143-145.


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