Superficial contamination of bovine carcasses by Escherichia coli O157:H7 in a slaughterhouse in Normandy (France)

In 1997, analyses were carried out on 255 bovine carcasses to determine the extent of superficial contamination by E. coli O157. A 50-cm2 meat sample taken from all carcasses was collected and tested using immunomagnetic separation method to detect E. coli O157. One strain of E. coli O157 bacterium was isolated and sent to the reference national center (Institut Pasteur, Paris). The strain was confirmed as E. coli O157:H7 and found to contain two out of the three pathogenicity genes (eae and EHEC-hlyA) necessary for enteropathogenicity. Shiga toxin genes were not detected. Superficial contamination of E. coli O157:H7 was established, but at low level (0.4%).