Biological indicator (BI)

Sterile processing definition

A biological indicator is a test system containing a known population of highly resistant bacterial spores, used to show whether a sterilization process was able to kill microorganisms. After the cycle, the BI is incubated: no growth means the spores were killed; growth (a positive BI) means the process may have failed. Steam BIs use Geobacillus stearothermophilus spores.

On the CRCST exam

Expect questions on which organism goes with which sterilization method, when BIs are run (routinely and with every implant load) and what to do after a positive result.

Exam domain: Sterilization Process (about 21% of the exam)

Sterilization Process practice questions

The conditions steam sterilization needs
Prevacuum steam cycle time and temperature
Wet packs after steam sterilization
How to load basins in a steam sterilizer

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