Chemical Decontamination of Footwear Soles to Limit Microbial Transfer in a Dry ...
Mar 15, 2014
Decontamination of footwear soles by chemical sanitizers is often used in food processing facilities to control the ingress of pathogenic microorganisms and their spread over floor surfaces, although little has been published to validate effectiveness. This study evaluated four decontamination treatments for efficacy in reducing microbial populations on footwear soles and for reducing transfer of those populations from soles to floors. Boot soles were inoculated with a mixture of equal parts of Citrobacter freundii, Pseudomonas fluorescens, and Serratia marcescens, donned, and subjected to treatment with aqueous quaternary ammonium sanitizer (Aqueous QAC, 1000 ppm) in a footbath mat, dry quaternary ammonium sanitizer (Dry QAC, 1.2% (wt/wt)) in a footbath mat, a spray of sanitizer containing 58.6% isopropyl alcohol and 150 ppm quaternary ammonium compounds (IPA QAC), and an IPA QAC spray followed by Dry QAC in a footbath mat (IPA QAC / Dry QAC). Before and after treatment, footwear soles and floor surfaces were sampled. No significant reductions in microbial populations on soles were observed upon treatment with Aqueous QAC, Dry QAC, compared with no treatment (control). Decontamination with IPA QAC and IPA QAC / Dry QAC resulted in 2.3 and 3.5 log reductions, respectively. Populations recovered from floor surfaces indicated IPA QAC and IPA QAC / Dry QAC treatments significantly reduced transfer of bacteria. Results of this study demonstrate that use of IPA QAC for decontamination of footwear may provide a significant barrier against the spread of microorganisms by foot traffic.