A Type 5 (integrating) chemical indicator strip placed inside a wrapped instrument tray shows the correct endpoint colour change after a prevacuum steam cycle. What does a passed Type 5 indicator actually confirm?

• A That the contents of the tray are sterile
• B That steam penetrated the wrapper but nothing more
• C That all bacterial spores in the chamber have been destroyed
• D That the package was exposed to conditions of time, temperature and saturated steam within the stated performance requirements ✓

Explanation

A Type 5 integrating indicator reacts to all critical variables of a steam cycle, namely exposure time, temperature and the presence of saturated steam, and its response is designed to parallel the performance of a biological indicator. However, it measures physical conditions only. It cannot confirm sterility of the contents (option A) or prove spore killing (option C); biological monitoring with Geobacillus stearothermophilus remains the definitive lethality test.

Reference: Block's Disinfection, Sterilization, and Preservation, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.