The sterile supply department validates a new ethylene oxide sterilizer used for heat-sensitive plastic devices. Which biological indicator organism is the accepted standard for monitoring ethylene oxide sterilization?
- A Geobacillus stearothermophilus
- B Bacillus atrophaeus (formerly Bacillus subtilis var niger) ✓
- C Clostridium sporogenes
- D Bacillus pumilus
Correct answer: B. Bacillus atrophaeus (formerly Bacillus subtilis var niger)
Explanation
Bacillus atrophaeus spores are the reference biological indicator for ethylene oxide and also for dry heat sterilization, because they show high resistance to alkylating agents and desiccation. Geobacillus stearothermophilus is the indicator for moist heat and hydrogen peroxide plasma, so it would falsely validate an ethylene oxide failure mode. Clostridium sporogenes is used in food canning studies and Bacillus pumilus historically monitored ionising radiation.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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