Hazard Group 3 agent decontamination using hydrogen peroxide vapour in a class III microbiological safety cabinet

Aims: This study investigated the efficacy of hydrogen peroxide vapour (HPV) at inactivating hazard group 3 bacteria that have been presented dried from their growth medium to present a realistic challenge. 

Methods and Results: Hydrogen peroxide vapour technology (Bioquell) was used to decontaminate a class III microbiological safety cabinet containing biological indicators (BIs) made by drying standard working suspensions of the following agents: Bacillus anthracis (Ames) spores, Brucella abortus (strain S99), Burkholderia pseudomallei (NCTC 12939), Escherichia coli O157 ST11 (NCTC 12079), Mycobacterium tuberculosis (strain H37Rv) and Yersinia pestis (strain CO92) on stainless steel coupons. Extended cycles were used to expose the agents for 90 min. The HPV cycle completely inactivated B. anthracis spores, B. abortus, B. pseudomallei, E. coli O157 and Y. pestis when BIs were processed using quantitative and qualitative methods. Whilst M. tuberculosis was not completely inactivated, it was reduced by 4 log₁₀ from a starting concentration of 10⁶ colony-forming units. 

Conclusions: This study demonstrates that HPV is able to inactivate a range of HG3 agents at high concentrations with associated organic matter, but M. tuberculosis showed increased resistance to the process. Significance and Impact of the Study: This publication demonstrates that HPV can inactivate HG3 agents that have an organic load associated with them. It also shows that M. tuberculosis has higher resistance to HPV than other agents. This shows that an appropriate BI to represent the agent of interest should be chosen to demonstrate a decontamination is successful.