Escherichia coli O157:H7 is among the most pathogenic of all known foodborne pathogens. It causes severe diarrhoea with apparently low infective dose (< 10 cells). This study aimed to determine the prevalence of E. coli O157:H7 in foods of animal sources sold in Sokoto Metropolis, Sokoto, Nigeria. A total of 175 samples were collected from different locations within Sokoto metropolis. Culture and biochemical characterisation revealed E. coli with an overall detection rate of 50.9% (89/175) with percentages of isolation rates of 30% (12/40), 75% (30/40), 43.6% (24/55) and 57.5% (23/40) for fresh milk, fermented milk, egg and raw meat respectively. Further characterization of the isolated E. coli on Sorbitol MarcConkey (SMAC) agar yielded E. coli O157:H7 strain with a positive detection rate of 31.4% (55/175) comprising 22.5% (9/40), 50.0% (20/40), 18.2% (10/55) and 40.0% (16/40) for fresh milk, fermented milk, egg and raw meat respectively. Molecular identification of shiga-toxin 1 (Stx I) and shiga-toxin 2(Stx II) genes in the E. coli O157:H7 isolates by polymerase chain reaction (PCR) yielded 10 amplicons of Stx 1 genes and 6 amplicons of Stx II genes. The study confirmed the presence of toxigenic E. coli O157:H7 in animal products sold within Sokoto metropolis. The application of Hazard Analysis Critical Control Point (HACCP) protocol in the production processes is recommended to identify probable sources of microbial contaminants and to appropriately prevent contamination. The public should be enlightened on the zoonotic potential of this foodborne pathogen and the role of good hygiene practices in food safety.
Keywords: Escherichia coli O157:H7, Shiga-like toxin, Sorbitol MacConkey agar.