Frequency of Shiga toxin-producing Escherichia coli (STEC) isolates among diarrheic and non-diarrheic calves in Brazil

The occurrence of Shiga toxin (Stx) gene sequences was examined in 344 fecal samples from diarrheic (n = 139) and non-diarrheic (n = 205) calves from 12 beef farms in São Paulo State, Brazil to study the prevalence of Shiga toxin-producing Escherichia coli (STEC) strains. Forty-four (12.7%) animals were found to be positive for stx. the frequency of carriage of stx was higher in diarrheic calves (28/139, 20%) than in non-diarrheic animals (16/205, 7.8%) (P < 0.001). Among the 24 STEC strains recovered from the animals, 12 isolates carried stx1, four stx2, and 8 carried both stx1 and stx2 genes. the eae and the enterohaemolysin (Ehly) gene sequences occurred at high frequencies in these STEC strains (41.6 and 50.0%, respectively). A total of 16 serotypes were identified. the serotypes O111:NM (four isolates), O111:H8 (two) and O118:H16 (one), currently described as enterohaemorrhagic E. coli (EHEC), were isolated from cattle in Brazil for the first time. These findings reinforce the importance of cattle as a reservoir of EHEC strains in Brazil. (C) 2003 Elsevier B.V. All rights reserved.Univ São Paulo, Inst Ciencias Biomed 2, Dept Microbiol, BR-05508900 São Paulo, BrazilUniv Estadual Campinas, Inst Biol, Dept Microbiol, BR-13081970 Campinas, SP, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilInst Adolfo Lutz Registro, Setor Enterobacterias, Dept Microbiol, BR-01246902 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc