RESUMO
AIMS: To determine the prevalence of Shiga toxin-producing Escherichia coli (STEC) and serotypes and virulence markers of the STEC isolates from beef and dairy cattle in Rio Grande do Sul, Brazil. METHODS AND RESULTS: Faecal samples from beef cattle were collected at slaughterhouses. The isolates were submitted to colony hybridization assay with specific DNA probes for stx1, stx2 and eae genes, and serotyped for the identification of O and H antigens. Thirty-nine per cent of beef cattle surveyed harboured at least one STEC strain. Among the distinct serotypes identified, 10 were shared by both beef and dairy cattle. Most of the strains isolated harboured stx2. Genotypic and phenotypic profiles allowed the identification of 34 and 31 STEC strains, isolated from beef and dairy cattle, respectively. Serotypes O10:H14, O15:H21, O96:H21, O119:H4, O124:H11, O128:H21, O137:H-, O141:H19, O159:H42, O160:H2 and O177:H11, identified in this study, have not been previously reported as STEC isolated from cattle. CONCLUSIONS: Cattle are an important reservoir of STEC strains associated with human diseases in South America. SIGNIFICANCE AND IMPACT OF THE STUDY: Determining the prevalence, genotypic profile and serotypes of STEC strains isolated from cattle enables the prediction of possible risk for public health.
Assuntos
Bovinos/microbiologia , Escherichia coli/classificação , Escherichia coli/patogenicidade , Toxinas Shiga/biossíntese , Animais , Brasil , Indústria de Laticínios , Reservatórios de Doenças , Escherichia coli/isolamento & purificação , Escherichia coli/metabolismo , Infecções por Escherichia coli , Fezes/microbiologia , Humanos , Carne/microbiologia , Sorotipagem , Toxinas Shiga/genética , Fatores de Virulência/genéticaRESUMO
Two distinct diarrheagenic Escherichia coli pathotypes, enteroaggregative E. coli (EAEC) and Shiga toxin-producing E. coli, were observed in association with O113 strains isolated from human and nonhuman sources in Brazil, respectively. The O113 strains from human diarrhea belonged to a diversity of serotypes, and nine (53%) of them harbored virulence traits of typical EAEC.
Assuntos
Doenças dos Bovinos/microbiologia , Diarreia/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli/classificação , Escherichia coli/patogenicidade , Animais , Aderência Bacteriana , Brasil/epidemiologia , Búfalos/microbiologia , Bovinos , Chlorocebus aethiops , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Proteínas de Escherichia coli/genética , Células HeLa , Humanos , Carne/microbiologia , Sorotipagem , Toxina Shiga/metabolismo , Células Vero , VirulênciaRESUMO
In order to determine the occurrence, serotypes and virulence markers of Shiga toxin-producing Escherichia coli (STEC) strains, 153 fecal samples of cattle randomly selected from six dairy farms in Sao Paulo State, Brazil, were examined for Shiga toxin (Stx) production by the Vero cell assay. Feces were directly streaked onto MacConkey Sorbitol Agar and incubated at 37 degrees C overnight. Sorbitol-negative colonies (maximum 20) and up to 10 sorbitol-positive colonies from each plate were subcultured onto presumptive diagnostic medium IAL. Sorbitol-negative isolates were screened with O157 antiserum for identification of O157:H7 E. coli. Isolates presenting cytotoxic activity were submitted to colony hybridization assays with specific DNA probes for stx1, stx2, eae, Ehly and astA genes. The isolation rate of STEC ranged from 3.8 to 84.6% depending on the farm analysed. STEC was identified in 25.5% of the animals, and most of them (64.1%) carried a single STEC serotype. A total of 202 STEC isolates were recovered from the animals, and except for the 2 O157:H7 isolates all the others expressed cytotoxic activity. The great majority of the STEC isolates carried both stx1 and stx2 genes (114/202, 56.4%) or stx2 (82/202, 40.6%); and whereas the Ehly sequence occurred in most of them (88%) eae was only observed in O157:H7 and O111:HNM isolates. Serotypes O113:H21, O178:H19 and O79:H14 were the most frequent STEC serotypes identified and widely distributed among animals from different farms, while others such as O77:H18, O88:H25 and O98:H17 occurred only in particular farms. This is the first report on the occurrence of STEC in dairy cattle in Sao Paulo State, and the results point to substantial differences in rate of isolation, serotypes and genetic profile of STEC that has been previously described among beef cattle in our community. Moreover, to our knowledge O79:H14 and O98:H17 represent new STEC serotypes, while O178:H19 has only been recently reported in Spain.
Assuntos
Doenças dos Bovinos/microbiologia , Infecções por Escherichia coli/veterinária , Escherichia coli O157/classificação , Toxina Shiga I/biossíntese , Toxina Shiga II/biossíntese , Adesinas Bacterianas/genética , Adesinas Bacterianas/metabolismo , Animais , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Brasil , Bovinos , DNA Bacteriano/química , DNA Bacteriano/genética , Indústria de Laticínios , Infecções por Escherichia coli/microbiologia , Escherichia coli O157/genética , Escherichia coli O157/crescimento & desenvolvimento , Escherichia coli O157/patogenicidade , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Fezes/microbiologia , Feminino , Hibridização de Ácido Nucleico , Antígenos O/metabolismo , Sorotipagem , Toxina Shiga I/genética , Toxina Shiga II/genéticaRESUMO
Twenty-nine Shiga toxin-producing Escherichia coli (STEC) strains were identified in a collection of 2,607 isolates from patients with diarrhea in São Paulo, Brazil, from 1976 to 1999. The STEC strains belonged mainly to serotypes O111:HNM (HNM, nonmotile) (13 of 29 [44.8%]), O111:H8 (7 of 29 [24%]), and O26:H11 (4 of 29 [13.8%]); stx(1) eae (26 of 29 [89.6%]), in combination with either enterohemorrhagic E. coli hlyA (11 of 26 [42%]) or astA (24 of 26 [92.3%]), prevailed. The O111 STEC strains were distinguished by their inability to decarboxylate lysine. The predominance of STEC O111 and O26 since the late 1970s and the identification of STEC serotypes O55:H19, O93:H19, and O118:H16 in association with human infections in Brazil are described for the first time.