Production of Shiga-Toxin by Escherichia coli O157:H7 isolated from Raw Cow Milk obtained within Kaduna Metropolis, Nigeria

Shiga toxin-producing Escherichia coli O157: H7 (STEC) is a food-borne pathogen that is associated with human illnesses from mild gastroenteritis to severe life-threatening hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. Its pathogenesis can be enhanced by the occurrence of certain virulence genes and the ability to produce biofilm. The present study investigates the spectrum of such pathogenesis on the basis of the occurrence of shiga-toxigenic E. coli O157:H7 in raw cow milk obtained from cattle herds. Furthermore, the inhibitory potential of some selected essential oils against their biofilm formation was determined. Results revealed isolated shiga-toxigenic E. coli O157:H7 harboured the stx1 and stx2 virulence genes. Inhibitory assessments of cinnamon, clove, eucalyptus, and tea tree oils also revealed impairment of biofilm formation at 1%, 2% and 3% concentrations, with cinnamon having a higher inhibitory impact. The presence of E. coli 0157:H7 in raw cow milk suggests that they are not restricted to contaminating raw meat only, but can be a contaminant of dairy products as well. The combined effect of stx1, stx2, and biofilm formation is of public health concern as plasmid transfer among strains could result in antimicrobial resistance. Phytochemicals from plants such as cinnamon, clove, eucalyptus, and tea tree could play vital biofilm inhibitory roles in decreasing the virulence of E. coli 0157:H7.