AST Surgical Technologist Practice Exam

What is the most reliable method for determining the efficiency of moist heat sterilizers?

1. Temperature recordings

2. Time logs

3. Biological indicators containing the organism Bacillus stearothermophilus

4. Chemical indicators

The correct answer is: Biological indicators containing the organism Bacillus stearothermophilus

The most reliable method for determining the efficiency of moist heat sterilizers is the use of biological indicators containing the organism Bacillus stearothermophilus. This organism is a well-established standard for testing steam sterilization processes due to its high resistance to heat and its ability to indicate whether the sterilization conditions were sufficient to kill microbial spores. Biological indicators work by placing these spores in a sterile environment subjected to steam sterilization. After the sterilization cycle, the biological indicator is then incubated. If the spores survive and grow, it indicates that the sterilization process was ineffective. Conversely, if the spores do not grow, it demonstrates that the sterilization process was successful in eliminating the bacterial load. While temperature recordings and time logs are important for monitoring the operation of sterilizers, they do not directly confirm that the sterilization process was effective. Temperature can be met, and time can be logged without achieving sterilization if the conditions necessary to kill spores are not adequately met. Chemical indicators, which change color or appearance based on temperature and time, are useful but are not as definitive as biological indicators since they do not prove that microbial death has occurred. Therefore, using Bacillus stearothermophilus as a biological indicator is the gold standard