Routine culturing is indicated for which of the following?

• A. Air sampling in airborne infection isolation rooms (AIIRs)
• B. Biological monitoring of sterilizers
• C. Water sources in oncology unit
• D. Environmental surfaces in NICU

Answer: (B)

Biological monitoring of sterilizers is the routine way to verify that a sterilization cycle actually achieves sterility. It uses indicators containing highly resistant spores placed with the load. After the cycle, the indicators are incubated; no growth means the process worked and the instruments are considered sterilized, while any growth signals a failure that requires reprocessing and equipment checks. This direct confirmation of the sterilization outcome is why routine culturing of sterilizers is performed.

Air sampling in AIIRs is about assessing the room environment, not validating a sterilization process. Water testing in oncology units and environmental surface sampling in the NICU serve other infection-prevention purposes and aren’t used for routine confirmation that sterilization has been effective, though they may be part of broader surveillance programs.