Combining spore germination and heat inactivation to decontaminate materials contaminated with Bacillus anthracis spores.

AIMS

To add a spore germination step in order to reduce decontamination temperature and time requirements compared to the current hot, humid air decontamination parameters, which are 75-80°C, ≥72 h, 70-90% RH, down to ≤60°C and ≤24 h total decontamination time.

METHODS AND RESULTS

Bacillus anthracis spore germination with l-alanine+inosine+calcium dipicolinate (CaDPA) was quantified at 0-40°C, several time points and spore concentrations of 5-9 log per ml. Germination efficiency at 0-40°C was >99% at <8 log spores per ml. The temperature optimum was 20°C. Germination efficiency was significantly higher but slower at 0°C compared to ≥30°C at ≥8 log spores per ml. A single germinant application followed by 60°C, 1-h treatment consistently inactivated >2 log (>99%) of spores. However, a repeat application of germinant was needed to achieve the objective of ≥6 log spore inactivation out of a 7 log challenge (≥99·9999%) for ≤24 h total decontamination time for nylon and aircraft performance coating.

CONCLUSIONS

l-alanine+inosine+CaDPA stimulated germination across wide temperature and spore concentration ranges.

SIGNIFICANCE AND IMPACT OF THE STUDY

Germination expands the scope of spore decontamination to include materials from any industry sector that can be sprayed with an aqueous germinant solution.