Shiga toxin–producing Escherichia coli isolated from pasteurized dairy products from Bahia, Brazil

The presence of pathogenic Shiga toxin–producing Escherichia coli (STEC) in dairy products represents a public health concern because its ability to produce the toxins Stx1 and Stx2, which cause intestinal diseases. Monitoring stages milk production checking for contamination are crucial steps ensure safety. This study aimed report occurrence thermotolerant coliforms, E. coli, STEC strains pasteurized evaluate antibiotic resistance profiles, serotypes, characterizations isolates by pulsed-field gel electrophoresis. We obtained total 138 from 15 processing plants Bahia, Brazil, examine strains. found that 43% samples (59/138) contained 30% (42/138) did not comply with Brazilian regulations. Overall, 6% (9/138) were positive 4% (5/138) STEC. recovered 9 cream (2/9), Minas Padrão cheese Frescal (4/9), ricotta (1/9). All stx2-positive, 2 eae-positive. negative “big 6” serogroups, belonging instead serotypes ONT:HNT, ONT:H12, O148:H−, OR:H40, OR:HNT, O148:HNT. Pulsed-field electrophoresis revealed 100% genetic similarity among 3 different produced same facility, may suggest cross-contamination. As well, we 98% similar but facilities, suggesting mutual source or circulating strain. Two exhibited streptomycin. Although presented low profile no strain belonged group, circulation stx2-positive ready-to-eat highlights importance epidemiological surveillance inside chain.