Which biological indicator is most commonly used to test the sterility of autoclave processes?

The most commonly used biological indicator for testing the sterility of autoclave processes is Bacillus stearothermophilus spores. This microorganism is particularly well-suited for this purpose because it is a heat-resistant spore-forming bacterium that can survive the high temperatures typically used in autoclaving (121 degrees Celsius or more).

The presence of Bacillus stearothermophilus spores in a test vial indicates the effectiveness of the autoclave: if the spores are killed during the sterilization process, the autoclave is functioning properly. Conversely, if the spores survive, it suggests that the sterilization process was inadequate.

While Bacillus subtilis, Bacillus cereus, and Clostridium botulinum can be involved in various sterility testing applications, they are not the standard for assessing the effectiveness of autoclaves. Bacillus subtilis is often used for other types of sterilization validation, and Clostridium botulinum spores are not a preferred indicator for this application due to their different environmental and growth conditions. Bacillus cereus is also not typically used as a standard biological indicator for autoclave processes. Therefore, Bacillus stearothermophilus remains the preferred choice in laboratories for