Effects of Different Sanitizers on the Toxin Production of Non-O157 Shiga Toxin-producing Escherichia coli Serotypes

Introduction: Foodborne outbreaks caused by non-O157 Shiga toxin-producing Escherichia coli (nSTEC) has increased in recent years. STEC strains can cause diarrhea, hemorrhagic colitis and in some severe cases potentially life threatening haemolytic uremic syndrome (HUS). Toxins produced by nSTEC are critical virulence factor that contribute to the intestinal epithelia damage and to the development of HUS. 

Purpose: Investigate the effect of different common chemical decontamination systems on nSTEC toxin production using a quantitative microtiter cytotoxicity assay.

Methods: Shiga toxin-producing E. coli serotypes O26, O103, O45, O111, O121 and O145 (nSTEC) were used in this study. Toxins were partially purified and exposed to different stress (100 ppm peroaxyacetic acid, 25% octanoic acid, 4% lactic acid and 100 ppm sodium hypochlorite solutions). After neutralization, toxin serial dilutions were added to Vero cell cultures. A staining procedure was used to evaluate cells attachment to monolayers and consequently the toxins potency. Cytotoxic effects were quantitatively measured by a spectrophotometer. 

Results: Cell detachment varied as a function of cell concentration, incubation time and stress agent. Significant difference (P < 0.05) between control and stress conditions were observed when toxins were treated with peroaxyacetic acid and sodium hyphochlorite solutions, while no significant effects were observed (P > 0.05) with octanoic acid and lactic acid solutions.

Significance: Findings of this study could be useful to direct future antimicrobial strategies in the food industry.