Shiga Toxin-Producing Escherichia coli (STEC) O157:H7 in Beef

Abstract

This study aimed to assess the hygienic-sanitary quality of raw beef sold in supermarkets and street markets in the Recôncavo region of Bahia, Brazil. Between May and July 2023, twenty-four samples were collected from six municipalities. The analyses included counts of mesophilic and psychrotrophic aerobic microorganisms, total coliforms, Escherichia coli , and the detection of Salmonella spp. Isolates of E. coli were subjected to genotypic characterization by Polymerase Chain Reaction (PCR) to identify virulence genes, focusing on the Shiga toxin gene ( stx ), indicative of enterohemorrhagic E. coli (EHEC), and the ST-I toxin gene ( stI ), associated with enterotoxigenic E. coli (ETEC). Results revealed that 75% of the samples did not comply with the microbiological standards established by current legislation for one or more tested microorganisms. Compliance was observed only in 25% of the establishments, exclusively in supermarkets. The stI gene was not detected in any isolate, while the stx gene was identified in two samples collected from street markets in the municipalities of Cachoeira and Santo Amaro. These findings indicate that a significant portion of beef marketed in the region presents unsatisfactory microbiological quality, posing potential risks to consumer health.