Geobacillus stearothermophilus
Pronunciation: jee-oh-bah-SIL-us steer-oh-ther-MOFF-ih-lus
A heat-resistant bacterial spore used as the standard biological indicator organism for steam sterilization validation.
Full Definition
Geobacillus stearothermophilus is a thermophilic, spore-forming bacterium that serves as the international standard test organism for steam sterilization processes. Its spores demonstrate exceptional resistance to moist heat, making them ideal for validating steam sterilization effectiveness. The organism's D-value (decimal reduction time) at 121°C is well-established, allowing precise calculation of sterilization parameters. Biological indicators containing G. stearothermophilus spores are placed in the most challenging locations within sterilizer loads to verify that sterilization conditions have been achieved throughout the chamber. Spore survival indicates sterilization failure, while spore kill confirms process efficacy.
Usage
Usage note: Genus name should be italicized in formal documents; commonly abbreviated as 'G. stearothermophilus' after first use.
In Context
- "The Geobacillus stearothermophilus biological indicators showed complete spore kill after the 15-minute exposure." — Sterilization validation report
- "Weekly biological indicator testing using Geobacillus stearothermophilus confirmed sterilizer performance." — Quality assurance documentation