Prevalence of Shiga toxin-producing Escherichia coli (STEC) O157:H7 in beef from a peripheral country

The objective of this study was to diagnose the hygienic-sanitary quality of raw beef sold in supermarkets and street markets in Recôncavo of Bahia. Twenty-four samples of beef from six municipalities located in the region were evaluated between May and July 2023. The samples were evaluated for the presence of mesophilic and psychrotrophic aerobic microorganisms, total coliforms, Escherichia coli and Salmonella spp. The E. coli isolates were subjected to genotypic characterization using Polymerase Chain Reaction (PCR) to verify the E. coli virulence genes, including the gene for Shiga toxin (stx) to identify enterohemorrhagic E. coli (EHEC) and the gene for ST-I toxin (stI) to identify enterotoxigenic E. coli (ETEC). The results indicate a high microbiological count with a total of 75% of the samples not complying with the parameters established in legislation for one or more microorganisms described. Only 25% of the total establishments checked, corresponding to supermarkets, complied with the legislation. The stI gene was not identified in any of the samples studied and the stx gene was identified in two samples sold in street markets in the municipalities of Cachoeira and Santo Amaro. It is concluded that part of the beef sold in supermarkets and street markets in the six municipalities has unsatisfactory microbiological quality, which may pose risks to the health of consumers.