Characterization of non-Shiga-toxin-producing Escherichia coli O157 strains isolated from dogs.

Shiga toxin-negative Escherichia coli O157 strains of various H types have been associated with diarrhea in children and are considered potentially pathogenic for humans. In this study, we describe non-Shiga toxin-producing E. coli O157 E. coli strains previously obtained from dogs in Argentina. Different E. coli phylogenetic lineages corresponding to flagellar types H16, H29 and H45 were identified. E. coli serotypes O157:H16 and O157:H45 contained intimin subtypes epsilon and alpha 1, respectively. Serotype O157:H45 carried the bfp gene encoding the bundle-forming pilus. Localized adherence-like patterns to HEp-2 cells were observed in O157:H16 strains, while O157:H45 adhered in a typical localized pattern. A total of eight different XbaI-pulse field electrophoresis patterns with more than 74 % similarity were identified among the nine E. coli O157:H16 strains. Our data emphasized the fact that dogs may harbor human pathogenic E. coli O157 which do not correspond to Shiga toxin-producing strains and whose potential human health hazard should not be underestimated.

[Detection and characterization of Shiga toxin-producing Escherichia coli from clinical cases and food in Uruguay]. / Detección y caracterización de Escherichia coli productor de toxina Shiga a partir de casos clínicos y de alimentos en Uruguay.

We have assessed the frequency of Shiga toxin-producing Escherichia coil (STEC) in clinical and food samples as well as studied the genotypic and phenotypic characteristics of the recovered strains. One hundred ninety eight fecal samples from children with bloody diarrhea (BD), 14 from children with hemolytic uremic syndrome (HUS), 220 ground beef samples and 4 STEC isolates from other beef-derived products were analyzed. The STEC strains were isolated from 3 (1.5%) children with bloody diarrhea, 1 (7%) from a child with HUS and 4 (1.8%) from ground beef samples. All strains were eae and ehxA positive. The serotypes found were: O157:H7 (9 strains), O26:H11 (2), O111: NM (1) and O145:HNT (1). All O157:H7 STEC strains harbored the eae subtype gamma1, O26:H11 and O145:HNT strains, subtype beta1 and O111:NM strain, subtype gamma2/theta. The STEC strains of the same serogroup showed high genetic diversity. In Uruguay, STEC is not frequently isolated from cases of bloody diarrhea in children. However, all the recovered STEC strains carried the genes associated with severe disease and 2 out of 3 children infected with STEC developed HUS. Ground beef and other food products might be important vehicles for O157:H7 strains.

Detección y caracterización de Escherichia coli productor de toxina Shiga a partir de casos clínicos y de alimentos en Uruguay / Detection and characterization of Shiga toxin - producing Escherichia coli from clinical cases and food in Uruguay

Establecimos la frecuencia de aislamiento de Escherichia coli productor de toxina Shiga (STEC) a partir de muestras clínicas y de alimentos, así como las características fenotípicas y genotípicas de las cepas recuperadas. Se analizaron 198 muestras fecales de niños con diarrea sanguinolenta (DS), 14 muestras fecales de niños con síndrome urémico hemolítico (SUH) y 220 muestras de carne picada. También se estudiaron 4 cepas STEC aisladas de alimentos embutidos. Se recuperó STEC de 3 (1,5%) de los niños con DS, de 1 (7%) niño con SUH y de 4 (1,8%) de las muestras de carne picada. Todas las cepas fueron eae y ehxA positivas. Los serotipos detectados fueron: O157:H7 (9 cepas), O26:H11 (2 cepas), O111:NM (1 cepa) y O145:HNT (1 cepa). Todas las cepas O157:H7 portaron el subtipo eae-g1; las cepas O26:H11 y O145:HNT portaron el subtipo eae-b1 y la cepa O111:NM portó el subtipo eae-g2/q. Las cepas STEC del mismo serogrupo mostraron alta diversidad genética. En Uruguay STEC no sería agente frecuente de diarrea con sangre en niños. Sin embargo, las cepas recuperadas presentaron los genes asociados con enfermedad severa y 2 de los 3 niños infectados con STEC evolucionaron a SUH. La carne picada y otros alimentos serían vehículos importantes de O157:H7.

We have assessed the frequency of Shiga toxin-producing Escherichia coli (STEC) in clinical and food samples as well as studied the genotypic and phenotypic characteristics of the recovered strains. One hundred ninety eight fecal samples from children with bloody diarrhea (BD), 14 from children with hemolytic uremic syndrome (HUS), 220 ground beef samples and 4 STEC isolates from other beef-derived products were analyzed. The STEC strains were isolated from 3 (1.5%) children with bloody diarrhea, 1 (7%) from a child with HUS and 4 (1.8%) from ground beef samples. All strains were eae and ehxA positive. The serotypes found were: O157:H7 (9 strains), O26:H11 (2), O111: NM (1) and O145:HNT (1). All O157:H7 STEC strains harbored the eae subtype g1, O26:H11 and O145:HNT strains, subtype b1 and O111:NM strain, subtype g2/q. The STEC strains of the same serogroup showed high genetic diversity. In Uruguay, STEC is not frequently isolated from cases of bloody diarrhea in children. However, all the recovered STEC strains carried the genes associated with severe disease and 2 out of 3 children infected with STEC developed HUS. Ground beef and other food products might be important vehicles for O157:H7 strains.