Certified Surgical Technologist (CST) Practice Exam

How many hours must the steam sterilization biological indicator incubate?

1. 6

2. 12

3. 18

4. 24

The correct answer is: 24

The steam sterilization biological indicator must incubate for 24 hours to provide an accurate assessment of the effectiveness of the sterilization process. This incubation period is essential because it allows sufficient time for any surviving microorganisms to grow and reveal if the sterilization conditions were adequate for effective microbial destruction. During this time, if there are viable spores present in the biological indicator, they will multiply, leading to a change in the growth medium, which can be observed and evaluated. Shorter incubation periods, such as 6, 12, or 18 hours, may not allow enough time for bacterial growth to occur, potentially leading to false-negative results that could incorrectly indicate that the sterilization process was successful when it was not. Thus, adherence to the full 24-hour incubation timeline is crucial for ensuring patient safety and confirming that the sterilization process was effective.