Bactericidal efficacy of peracetic acid in combination with hydrogen peroxide against pathogenic and non pathogenic strains of Staphylococcus spp., Listeria spp. and Escherichia coli

The aim of this research was to evaluate the bactericidal efficacy of peracetic acid in combination with hydrogen peroxide (PAHP) against pathogenic and non pathogenic strains of Staphylococcus spp., Listeria spp. and Escherichia coli. Killing experiments were performed according to the European standard suspension test UNE-EN-1276. The PAHP was tested at five concentrations from 0.05% to 0.4% v/v and three exposure times (10, 20 and 30 min) using sterile semi-skim milk, orange juice, liquid egg and chocolate milk shake as interfering substances. Staphylococcus spp. showed more resistance at low concentrations of disinfectant than strains of E. coli and Listeria spp. Egg was the organic matter with greatest interfering capacity and orange juice was the one with least interfering capacity. However PAHP was effective (reductions of >5 log CFU/ml) at concentrations from 0.1% and 10 min of exposure in all cases. No statistical differences were found between pathogenic and non pathogenic strains in the same group. Consequently, when the utilization of pathogenic strains is not possible, they may be substituted by non pathogenic strains of the same group, obtaining similar reductions.