Evaluation of a Rapid Biological Spore Test for Dental Instrument Sterilization

Abstract

This study evaluated the reliability of a new rapid biological spore test (BST) for determining the sterilization efficacy of dental steam autoclaves within 20 minutes, as compared to a conventional BST requiring 2 days of incubation after autoclave exposure. A total of 177 pairs of BST, each composed of a rapid test (Celerity™ 20 Steam Biologic Indicator, Steris) and a conventional BST (Attest™ 1262 Biological Indicator, 3M), both containing Geobacillus stearothermophilus spores, were placed into steam autoclaves loaded with instruments, and subjected to either sterilizing (157 pairs) or non-sterilizing conditions (20 pairs). Celerity™ BST was then incubated for 20 minutes at 57°C, with the growth medium evaluated spectrophotometrically for fluorescent α-glucosidase signal changes (no change with successful sterilization; increased fluorescence after failed sterilization). Attest™ BST was incubated for 48 hours at 57°C, after which a pH-based color change in the culture broth was visually assessed (no change in purple color with successful sterilization; change to yellow color with failed sterilization). Celerity™ and Attest™ BST both accurately identified successful sterilization, with no G. stearothermophilus spore growth from either BST after exposure to sterilizing steam autoclave conditions (100% agreement between 157 pairs of each BST). Both BST also accurately detected unsuccessful sterilization, with all tested ampoules positive for G. stearothermophilus spore germination after non-sterilizing steam autoclave time periods. Both BST exhibited 100% sensitivity, specificity, and accuracy for detection of sterilizing steam autoclave conditions. Celerity™ BST, after only 20 minutes incubation, performed equally as well as a BST requiring 48 hours incubation in determining the sterilization efficacy of dental steam autoclaves. Rapid BST offer earlier detection of sterilization failure before potentially contaminated dental instruments are used in clinical patient care.