[Detection of verotoxin-producing E. coli (VTEC) in healthy cattle and swine with the DNA-DNA colony hybridization method].

With the DNA-DNA colony hybridization technique using specific gene probes for Verotoxin 1 (VT 1) and Verotoxin 2 (VT 2) 2100 E. coli strains from healthy animals were tested. Ten out of 82 milk cows (21.2%), 20 out of 212 beef cattle (9.4%) and five out of 75 pigs (6.7%) were found to carry genes for VT 1, VT 2 or both toxins, respectively. Among these strains the biotypes 5 and 6 were predominant. Some of the serotyped isolates have been described to be pathogenic for humans, like O157:H7, 082:H8, 0116, 0113, 0126 and 091, respectively. The unexpected high incidence of VTEC positive healthy animals possibly indicates a health hazard for human beings. Further investigations on the incidence of VTEC in food are necessary.