Isolation and genomic characterization of Escherichia coli O157:H7 in bile of cattle

Abstract

A total of 200 bile samples of cattle collected from two slaughterhouses from May to September 2007 were analyzed by immunomagnetic separation (IMS)-based cultivation technique. Two (1.0%) of the samples were found to be contaminated with E. coli O157:H7. One of the two isolates was found to carry all five virulence genes (fliCh7, stx1, stx2, eaeA and hly), and the other isolate was positive for these genes except st x2 by multiplex PCR. According to the PFGE, the strains isolated from two different bile samples displayed different XbaI REDP. Antibiotic susceptibility profiles indicated that two isolates were resistant to cephalothin and intermediately resistant to ampicillin, streptomycin and sulphamethoxazole. Also, one isolate was intermediately resistant to kanamycin. It is concluded that the gallbladder should be considered as a possible site and source of E. coli O157:H7 in cattle. © Springer-Verlag and the University of Milan 2010.