PREVALENCE OF BOVINE VEROTOXIN-PRODUCING ESCHERICHIA-COLI IN ARGENTINA

Faecal swabs obtained from 126 calves and 118 cows in Argentina were i nvestigated for the presence of verotoxin-producing Escherichia coli ( VTEC), VTEC strains were recovered from 10 (23%) of 43 calves with dia rrhoea, from 24 (29%) of 83 healthy calves, from 40 (44%) of 91 health y cows waiting at the slaughterhouse, and from 6 (22%) of 27 healthy g razing cattle. PCR showed that 21 (9%) of animals carried VT1(+) strai ns, 49 (20%) VT2(+) strains and 10 (4%) VT1(+) VT2(+) strains. VT1(+) strains predominated among calves (16% versus 0.8%; p < 0.001). The pr esence of eae gene was significantly more frequent among VTEC strains isolated from calves (78%; 46/59) than from cows (2%; 1/65) (p < 0.001 ). Furthermore, eae gene was more prevalent in VT1(+) strains (97%; 32 /33) than in VT2(+) strains (14%; 10/70) (p < 0.001) and in VT1(+) VT2 (+) strains (24%; 5/21) (p < 0.001). Sorbitol negative high virulent s trains serogroups O157 were not detected. This study indicates that ca ttle are a reservoir of VTEC strains, and that eae gene is associated with VT1(+) strains that are predominating among young animals. Fortun ately, only adult animals are taken to the slaughterhouse, among which VTEC strains negative for eae gen are predominating.