Inactivation of Francisella tularensis Schu S4 in a Biological Safety Cabinet Using Hydrogen Peroxide Fumigation

This study evaluated the inactivation of Francisella tularensis Schu S4 on various materials (acrylic, glass, polyamide, polyethylene, polypropylene, silicone rubber, and stainless steel) using hydrogen peroxide fumigation of a Class III Biological Safety Cabinet (BSC III). A suspension of F. tularensis Schu S4 (7 x 10 CFU) was dried on seven different types of test surfaces and exposed to vaporous hydrogen peroxide (VHP) fumigation for a contact time of two hours. Qualitative growth assessment showed that VHP exposure inactivated F. tularensis on all replicates of the seven test materials up to four days post-exposure. The effectiveness of VHP fumigation on the growth of biological indicators (Bacillus subtilis or Geobacillus stearothermophilus) and spore strips (Bacillus atrophaeus) was evaluated in parallel as a qualitative assessment of decontamination. At one and four days post-exposure, decontaminated biological indicators and spore strips exhibited no growth, while the non-decontaminated samples displayed growth. This study provides information for using VHP fumigation as an alternative approach for the decontamination of virulent F. tularensis when the current accepted method of 10% household bleach followed by 70% alcohol may not be practical for decontamination of a BSC III.