Detection of Superheated Steam during Sterilization Using Biological Indicators

Area of Science:

• Sterilization science
• Microbiology
• Medical device reprocessing

Background:

• Saturated steam (SS) is a standard for medical device sterilization, creating a microbicidal environment.
• Superheated steam (SHS), heated beyond its saturation point, is less microbicidal and compromises sterilization efficacy.
• Effective sterilization monitoring systems are crucial for detecting deviations like SHS.

Purpose of the Study:

• To evaluate the capability of rapid-readout self-contained biological indicators (RRSCBIs) to detect superheated steam (SHS).

Main Methods:

• RRSCBIs were exposed to saturated steam (SS) and superheated steam (SHS) under controlled conditions in a BI evaluation resistometer.
• SHS was reproducibly achieved with approximately 12°C or 4.5°C of superheat at nominal 121.75°C and 132.5°C cycles, respectively.
• RRSCBIs were tested in vertical, inverted, and horizontal orientations, with viability assessed via fluorescent readout.

Main Results:

• RRSCBIs exposed to SS were negative, confirming cycle efficacy.
• RRSCBIs detected SHS, but detection rates varied significantly with orientation.
• Higher detection rates of SHS were observed when RRSCBIs were placed horizontally or inverted compared to vertically.

Conclusions:

• RRSCBIs can serve as a detection method for superheated steam during sterilization processes.
• The orientation of RRSCBIs is a critical factor influencing their ability to detect SHS.
• Further research is needed to optimize RRSCBI use and interpret findings in clinical settings.