Serotypes and Shiga toxin genotypes among Escherichia coli isolated from animals and food in Argentina and Brazil

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains isolated from animals and food in Argentina (n = 44) and Brazil (n = 20) were examined and compared in regard to their phenotypic and genotypic characteristics to evaluate their pathogenic potential. the clonal relatedness of STEC O157 isolates (n = 22) was established by phage typing (PT) and pulsed-field gel electrophoresis (PFGE). All O157 strains studied carried eae and enterohemorrhagic E. coli (EHEC)-hly sequences. in Argentina, these strains occurred both in cattle and meat, and 50% of them carried stx2/stx2vh-a genes, whereas in Brazil the O157 strains were isolated from animals, and most harbored the stx2vh-a sequence. At least 13 different O:H serotypes were identified among the non-O157 strains studied, with serotype O113:H21 being found in both countries. All but one non-O157 strains did not carry eae gene, but EHEC-hlyA gene was found in 85.7% of them, and the stx2 genotype was also more prevalent in Argentina than in Brazil (P = 80%) to Argentinean strains of cluster I. Differences in the pathogenic potential, especially in regard to serotypes and stx genotypes, were observed among the STEC strains recovered from animals and food in both countries. (C) 2002 Elsevier Science B.V. All rights reserved.ANLIS Dr Carlos G Malbran, Inst Nacl Enfermedades Infecciosas, Serv Fisiopatogenia, RA-1281 Buenos Aires, DF, ArgentinaUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilUniv Fed Fluminense, Dept Microbiol & Parasitol, Niteroi, RJ, BrazilUNiv Estado Rio de Janeiro, Disciplina Microbiol & Imunol, Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilWeb of Scienc

Biochemical properties, enterohaemolysin production and plasmid carriage of Shiga toxin-producing Escherichia coli strains

Thirty-eight strains of Shiga toxin-producing Escherichia coli (STEC) were characterised in terms of biochemical properties, enterohaemolysin production and plasmid carriage. A wide variation in the biochemical properties was observed among the STEC, with 14 distinct biotypes identified. Biotype 1 was the most common, found in 29% of the strains. Enterohaemolysin production was detected in 29% of the strains. Most of the bacterial strains (95%) carried one or more plasmids and considerable heterogeneity in size and combinations was observed. Seven distinct plasmid profiles were identified. The most common profile, characterised by the presence of a single plasmid of ~90 kb, was found in 50% of these strains. These data indicate extensive diversity among STEC strains. No correlation was found among biotype, serotype, enterohaemolysin production and plasmid profile