When is a biological indicator considered positive?

A biological indicator is a crucial tool used in sterilization processes to confirm the effectiveness of sterilization methods. It typically consists of a specific type of microorganism that is resistant to the sterilization process being used. After the sterilization process, the biological indicator is incubated to allow any surviving microorganisms to grow.

The indicator is considered positive when there is visible growth in the ampule after incubation. This indicates that the sterilization process was not effective at killing all the microorganisms, meaning that some survived and multiplied. Thus, a positive result serves as a clear signal that the sterilization parameters may not have been met, requiring further investigation, reprocessing, or corrective action.

The other options offer different scenarios related to the biological indicator but do not define a positive test accurately. For instance, completion of the incubation process alone does not indicate a positive result, nor does a lack of growth in the ampule, which would instead signify successful sterilization. Similar reasoning applies to the scenario before sterilization, as it does not pertain to the evaluation of effectiveness post-process.