Determining the efficacy of liquid sporicides against spores of Bacillus subtilis on a hard nonporous surface using the quantitative three step method: collaborative study.

摘要: A collaborative study was conducted to validate the quantitative Three Step Method (TSM), a method designed measure performance of liquid sporicides on hard nonporous surface. Ten laboratories agreed participate in study; data from 8 10 participating were used final statistical analysis. The TSM uses 5x5x1 mm glass coupons (carriers) upon which spores have been inoculated and are introduced into sporicidal agent contained microcentrifuge tube. Following exposure test chemical neutralization agent, removed carriers 3 fractions: passive removal (Fraction A), sonication B), gentle agitation C). Liquid each fraction is serially diluted plated recovery medium for spore enumeration. Control counts compared treated counts, level efficacy determined by calculating logic reduction (LR) spores. main goals evaluate repeatability reproducibility LR values, estimate components variance LR, assess responsiveness. AOAC 966.04-Method II as reference method. scope validation limited testing formulations against Bacillus subtilis, surrogate virulent strains B. anthracis, surface (glass). chemicals sodium hypochlorite, combination peracetic acid hydrogen peroxide, glutaraldehyde. Each evaluated at levels presumed efficacy: high, medium, low. replications required. validated it successfully met parameters methods. Satisfactory parameters, such standard deviation (S r ) R ), obtained control carrier values. Both responsive chemicals. For 72 total tests conducted, mean (± error mean) log density per 6.86 0.08); S low 0.15 0.27, respectively. Across range chemicals, estimates associated with also acceptably ranged 0.17 0.72 0.34 1.43. Overall, within ranges published other methods meet characteristics necessary validation.