Infection Control · single question
The biological spore indicator used to test autoclave (steam sterilization) efficacy contains which organism?
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Correct answer: A. Geobacillus stearothermophilus (highly resistant, non-pathogenic)
- A. Correct. Geobacillus stearothermophilus (formerly Bacillus stearothermophilus) is the standard biological indicator for autoclave (steam sterilization) testing. It is highly resistant to moist heat (more resistant than most pathogens) and NON-PATHOGENIC — making it a safe and stringent test organism. If the autoclave kills this organism, it will kill all pathogens.
- B. Bacillus subtilis (less resistant) is used to test DRY HEAT sterilizers, not autoclaves.
- C. G. stearothermophilus is non-pathogenic; marking it as pathogenic is incorrect.
- D. Clostridium perfringens is a pathogen and is not used as a biological indicator for autoclave testing.
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