Sterilization Process Monitoring: Physical, Chemical, and Biological Indicators

Sterilization

A process that aims to destroy all pathogenic microorganisms on surgical instruments to prevent healthcare-associated infections (HAIs).

Quality Assurance Program (QAP)

A comprehensive program essential for ensuring confidence in sterility, as sterility cannot be observed with the naked eye. It includes physical monitors, chemical indicators, and biological indicators.

Physical Monitors

Printouts, displays, and gauges on the outside of the sterilizer that provide immediate verification that sterilization parameters have been met, but do not assess lethality directly.

Chemical Indicators (CIs)

Devices that respond to one or more physical conditions inside the sterilization chamber (e.g., time, temperature, saturated steam) to help verify that the sterilization process occurred as intended. They do not directly measure lethality.

Internal CIs

Chemical indicators placed deep inside a pack or container to verify that steam (or other sterilant) penetrated to the interior of the load.

External CIs

Chemical indicators placed on the outside of each pack or tray to distinguish between processed and unprocessed loads.

Biological Indicators (BIs)

Monitoring devices containing viable microorganisms (spores) with a defined resistance to a specified sterilization process, used to directly monitor the lethality of the sterilization cycle.

Geobacillus stearothermophilus

The organism of choice for biological indicators used in steam, hydrogen peroxide gas plasma, and ozone sterilization processes due to its thermophilic nature and highly resistant spore-forming capability.

Spore

A dormant, highly resistant form of bacteria that can withstand adverse conditions, making it an ideal challenge to test the efficacy of sterilization processes.

Process Challenge Device (PCD)

A device used to challenge the sterilization process in a BI test on a per-load basis, often containing a biological indicator to simulate the most difficult-to-sterilize conditions.

Lethality

The ability of a sterilization process to kill microorganisms, especially highly resistant spores, thereby ensuring that less resistant pathogens would also be destroyed.

Safety Margins