Sporicidal efficacy of hydrogen peroxide aerosol

Because of its high sporicidal activity but low toxicity, hydrogen peroxide (H2O2) is a useful agent for gentle antimicrobial treatment of irritable goods. Above all to optimise practical aspects of H2O2 application, sporicidal efficacy of aerosols based on 1% H2O2 solution was tested. Using commercially available bioindicators with Bacillus subtilis spores immobilized on filter paper strips, a 7 h lasting aerosol treatment at room temperature resulted in a reduction of viable count of 2.5 log10 (median, n = 5). By combined application of 0.3% sorbitan monolaurate (Span 20) and 1% H2O2 aerosol at room temperature, a reduction of viable count of >6.3 log10 (median, n = 5) could be reached within 2 h, already. Following aerosol treatment at 60 degrees C, all bioindicators tested (n = 15) have been found without growth after 10 min, corresponding to a reduction of viable count >6.3 log10. However, this efficacy was possible only if the spores were immobilized on filter paper strips. Changing the carrier materials lower sporicidal activity of H2O2 aerosol was found resulting in a reduction of viable count between >5.4 log10 (median, n = 15) on polyethylene foil and 0.4 log10 (median, n = 15) on glass slides. These differences could not be correlated with surface qualities as porosity or wettability.