Prevalence of Bovine Verotoxin-Producing Escherichia coli in Argentina

Faecal swabs obtained from 126 calves and 118 cows in Argentina were investigated for the presence of verotoxin-producing Escherichia coli (VTEC). VTEC strains were recovered from 10 (23%) of 43 calves with diarrhoea, from 24 (29%) of 83 healthy calves, from 40 (44%) of 91 healthy cows waiting at the slaughterhouse, and from 6 (22%) of 27 healthy grazing cattle. PCR showed that 21 (9%) of animals carried${\rm VT1}^{+}$strains, 49 (20%)${\rm VT2}^{+}$strains and 10 (4%)${\rm VT1}^{+}\ {\rm VT2}^{+}$strains.${\rm VT1}^{+}$strains predominated among calves (16% versus 0.8%; p < 0.001). The presence 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${\rm VT1}^{+}$strains (97%; 32/33) than in${\rm VT2}^{+}$strains (14%; 10/70) (p < 0.001) and in${\rm VT1}^{+}\ {\rm VT2}^{+}$strains (24%; 5/21) (p < 0.001). Sorbitol negative high virulent strains serogroups O157 were not detected. This study indicates that cattle are a reservoir of VTEC strains, and that eae gene is associated with${\rm VT1}^{+}$strains that are predominating among young animals. Fortunately, only adult animals are taken to the slaughterhouse, among which VTEC strains negative for eae gen are predominating.