An investigation into Escherichia coli O157:H7 and other shiga toxin-producing Escherichia coli in white veal calves .

摘要

This study determined the prevalence of Escherichia coli O157:H7 and other Shiga toxin-producing E. coli (STEC) in white veal calves and investigated factors that might affect prevalence. Fecal samples from cohorts of 21, 21, and 20 white veal calves were collected weekly for 20 weeks and processed using immunomagnetic separation for isolation of O157:H7 STEC and PCR for stx genes and ELISA for Shiga toxins in fecal broth cultures for detection of STEC. The prevalence rates for O157:H7 STEC were 0.17% of 1151 fecal samples and 3.2% of 62 calves, and 73% and 68% for STEC, by PCR and ELISA, respectively. Examination of sera from some calves indicated that approximately 40% of the calves were exposed to O157 LPS or cross-reactive antigens. The milk-based feed had antibodies to O157 LPS and other surface antigens as well as antibiotics that may contribute to the low fecal excretion of O157:H7 in the calves.