Medical Device Reprocessing Association of Ontario (MDRAO) 2025 – 400 Free Practice Questions to Pass the Exam

The correct answer is Geobacillus stearothermophilus because it is widely recognized as an effective biological indicator for steam sterilization processes. This organism is a thermophilic bacterium, meaning it thrives at elevated temperatures, making it particularly suitable for testing the efficacy of steam sterilization, which operates at high temperatures and pressure.

When using Geobacillus stearothermophilus as a biological indicator, the spores of this bacterium are introduced to a sterilization cycle. After the cycle is complete, they are subsequently incubated; if the spores survive, it indicates a failure of the sterilization process. Conversely, if the spores are not viable post-cycling, it demonstrates that the sterilization parameters were adequate.

Other organisms mentioned do not serve as suitable biological indicators for steam sterilization. While E. coli and Staphylococcus aureus are common bacteria that may be used in other contexts, they do not have the same thermal resistance properties as Geobacillus stearothermophilus. Bacillus cereus, although it does produce spores, is not the standard organism used for testing steam sterilization efficacy. The specific choice of Geobacillus stearothermophilus is based on established standards