OCCURRENCE, VIRULENCE GENES AND ANTIMICROBIAL RESISTANCE OF ESCHERICHIA COLI O157 IN BOVINE, CAPRINE, OVINE AND PORCINE CARCASSES IN GREECE

One thousand and two hundred carcasses (620 bovine, 130 caprine, 230 ovine and 220 porcine) from several slaughterhouses throughout Greece were examined for the presence of Escherichia coli O157 after evisceration and before chilling. Twelve E. coli O157 strains (1.0%) were isolated of which eight were from bovine (1.3%), one from caprine (0.8%) and three from ovine (1.3%) meat. None was isolated from pork meat. Six out of the 12 E. coli O157 isolates (50.0%) could be classified as Shigatoxigenic based on polymerase chain reaction (PCR), belonged to the E. coli O157:H7 serotype and were PCR-positive for the stx(1), stx(2) and eae genes except one isolate that was stx(1)-negative. The remaining six E. coli O157 isolates tested negative for Shiga-toxin production, both by immunoassay and by PCR, were PCR-negative for the eae gene, and all except one (strain LFH34, a bovine carcass isolate) were also PCR-negative for the H7 flagellar gene. Among the 15 antimicrobials tested, the E. coli O157 isolates were the most frequently resistant to ticarcillin (9 out of the 12 isolates, 75%).