Occurrence, pathotypes, and antimicrobial resistance profiles of diarrheagenic Escherichia coli strains in animal source food products from public markets in Mashhad, Iran

Diarrheagenic Escherichia coli (DEC) strains are common pathogens that transmitted through the consumption of contaminated foods, and cause acute intestinal diseases in human. The present study was conducted on 300 samples including raw milk, meat and some of their products from November 2016 to October 2017. Microbiological and molecular diagnostic techniques were used to identification of DEC. A total of 69% (207/300) E. coli was isolated and the frequency of DEC was 25.6% (53/207). The pathogenic groups of DEC recovered from the isolates had the following profile: Shiga-like toxin producing E. coli (STEC): 62.3%, enteropathogenic E. coli (EPEC): 24.5%, enteroaggregative E. coli (EAEC): 9.4%, and enterotoxigenic E. coli (ETEC): 3.8%. Neither enteroinvasive E. coli (EIEC) nor diffusely adherent E. coli (DAEC) were found. The highest incidence values were found in hamburgers (46.7%), and the highest rate of DEC positive prevalence was in March. Of the DEC strains, 90.6% (48/53) displayed resistance to at least one antibiotic and the highest level of resistance was found for tetracycline (69%). The obtained results revealed that the studied animal source food products may easily act as a reservoir of DEC with a potential ability to transfer antibiotic resistance and virulence genes to the gastrointestinal microbiota. Therefore, it is of paramount importance to develop effective strategies for improving food safety and updated guidelines for the prudent use of antimicrobial agents in Iran.