Geobacillus stearothermophilus is commonly used as a biological indicator for which of the following sterilization processes?

• A. Ethylene oxide sterilization
• B. Steam sterilization (autoclaving)
• C. Radiation sterilization
• D. Dry heat sterilization

Answer: (B)

Verified step by step guidance

1. Understand the role of Geobacillus stearothermophilus as a biological indicator: it is a microorganism used to test the effectiveness of sterilization processes by its ability to survive under specific conditions.
2. Recall that Geobacillus stearothermophilus is a thermophilic bacterium, meaning it thrives at high temperatures, which makes it particularly resistant to heat-based sterilization methods.
3. Identify the sterilization processes listed: Ethylene oxide sterilization, Steam sterilization (autoclaving), Radiation sterilization, and Dry heat sterilization.
4. Recognize that steam sterilization (autoclaving) uses saturated steam at high temperatures (usually around 121°C) and pressure to kill microorganisms, and Geobacillus stearothermophilus spores are highly resistant to this method, making them ideal for testing autoclave effectiveness.
5. Conclude that because Geobacillus stearothermophilus spores are used to verify the efficacy of steam sterilization, it is the correct biological indicator for the autoclaving process.