Characterization of eae(+) Escherichia coli isolated from healthy and diarrheic calves

Strains of Escherichia coli from 101 healthy and 114 diarrheic calves were screened by PCR for the ene (intimin) gene and Shiga toxin genes (stx.). Ea ch eae(+) and eae/stx(+) strain was examined for antimicrobial susceptibili ty, enterohemolysin activity, and the somatic O antigen was determined. An immunoassay was used to detect Shiga toxin antigens for the eae/stx(+) E. c oli. Significantly more (p = 0.005) of the healthy calves carried eae(+) an d eae/stx(+) E, coli in their feces when compared to strains from diarrheic calves. Moreover, Shiga toxin antigens were detected significantly more (p = 0.001) often among the ene/stx(+) strains from healthy calves when compa red to eae/stx(+) strains from diarrheic calves. However, significantly mor e (p = 0.001) of the eae(+) and eae/stx(+) strains from diarrheic calves we re resistant to at least one of the antimicrobials tested, and the strains from diarrheic calves had a significantly (p = 0.05) higher rate of antimic robial resistance to at least two different antimicrobial classes. No signi ficant difference (p greater than or equal to 0.05) was detected among the eae(+) and eae/stx(+) strains from healthy and diarrheic calves for enteroh emolysin production. Serogroups O-negative, O5, O26, and O111 were predomin ate among both healthy and diarrheic calves. (C) 1999 Elsevier Science B.V. All rights reserved.