Test method development to evaluate hot, humid air decontamination of materials contaminated with Bacillus anthracis DeltaSterne and B. thuringiensis Al Hakam spores.

摘要

Aims: To develop test methods and evaluate the survival of Bacillus anthracis ΔSterne and Bacillus thuringiensis Al Hakam spores after exposure to hot, humid air. Methods and Results: Spores (>7 logs) of both strains were dried on six different test materials. Response surface methodology was employed to identify the limits of spore survival at optimal test combinations of temperature (60, 68, 77°C), relative humidity (60, 75, 90%) and time (1, 4, 7 days). No spores survived the harshest test run (77°C, 90% r.h., 7 days), while > 65 logs of spores survived the mildest test run (60°C, 60% r.h., 1 day). Spores of both strains inoculated on nylon webbing and polypropylene had greater survival rates at 68°C, 75% r.h., 4 days than spores on other materials. Electron microscopy showed no obvious physical damage to spores using hot, humid air, which contrasted with pH-adjusted bleach decontamination. Conclusions: Test methods were developed to show that hot, humid air effectively inactivates B. anthracis ΔSterne and B. thuringiensis Al Hakam spores with similar kinetics. Signi?cance and Impact of the Study: Hot, humid air is a potential alternative to conventional chemical decontamination.