What is the purpose of biological indicators in sterilization validation?

• A. To measure the time to complete the cycle.
• B. To confirm that the sterilization process achieved the required level of sterility by testing a resistant organism.
• C. To monitor chemical concentrations in the sterilant.
• D. To track the expiration date of sterile supplies.

Answer: (B)

Biological indicators are used to confirm that a sterilization cycle actually achieves microbial destruction by challenging the process with a highly resistant organism. They contain spores of a tough microorganism and are placed in the most challenging spots of the load. After the cycle, the indicator is incubated to see if any organisms survived. If there is no growth, it shows the cycle achieved the required lethality and the sterilization process is validated for that load and conditions. If growth occurs, it indicates the cycle did not meet the necessary sterility level, signaling a failure that requires investigation and corrective action. This focus on actual microbial inactivation differentiates biological indicators from chemical indicators and from measurements of time or stock management factors like expiration dates.