Attenuation of E. coli O157:H7 virulence by a combination of natural plant extracts and organic acids before and after refrigerated storage

Anti-virulence strategies are an alternative approach to combat zoonotic bacterial pathogens. Although control measures are in place against E. coli O157, it still remains a global health concern with cattle being the most important reservoir. Different feed constituents have varying effects on the virulence of E. coli O157 present in the gut which then are transferred to meat processing surfaces and meat during slaughter. This study explored the anti-virulence properties of a mixture of natural plant extracts and organic acids (citrus, grape and oregano extracts, lactic and citric acid) before and after refrigerated storage as means of reducing the risk from E. coli O157 by reducing its virulence. Assessment of the effects of sub-inhibitory concentrations (0.1 and 0.5 %, v/v) of the antimicrobial mixture before refrigerated storage showed that the pathogen’s motility and adhesion onto HCT-8 cells was significantly reduced (P