Shiga toxin-producing and attaching and effacing Escherichia coli in cats and dogs in a high hemolytic uremic syndrome incidence region in Argentina

Shiga toxin-producing Escherichia coli (STEC), responsible for the hemolytic uremic syndrome, is an endemic pathogen in Argentina. We studied the prevalence of STEC in fecal samples from cats and dogs of Buenos Aires city and suburbs. Cultures were used for screening stx1/stx2 and rfbO157 by multiplex PCR. All E. coli-positive colonies for these genes were further characterized for the eae gene and for serotypes. In dogs, 17 (3.7%), 19 (4.2%) and 34 (7.5%) of samples were positive for stx2, stx1 and rfb, respectively. In cats, six (4.0%) of the samples were positive for stx2, three (2.0%) for stx1 and four (2.7%) for rfbO157. In 18 (4.0%) of the dog samples, a bacteriological diagnosis was obtained by isolation. The percentage of positive isolates corresponding to the rfbO157 and to the stx2 genotypes were 2.9% and 1.1%, respectively. In four of the cat samples, the bacteriological diagnosis for stx2 (2.6% prevalence of STEC) was confirmed. Although these data suggest that the high infection index of STEC in children in Argentina does not seem to be due mainly to the role of cats and dogs, there are some strains with virulence genes in common for humans and their domestic animals.