Incidence of common DNA sequences in bovine and porcine Escherichia coli strains causing diarrhoea.

Abstract Seventeen bovine and 56 porcine Escherichia coli isolates from cases of diarrhoea and from healthy animals were examined for DNA sequences homologous to the genes for verocytotoxins ( VT ), enterotoxins and human enterohaemorrhagic E coli /enteropathogenic E coli ( EHEC/SPEC ) sequences. VT -1 was the most common toxin among the bovine isolates and VT -2 the most common in the porcine isolates. No isolates had homologous sequences to enteropathogenic adherence factor, but 71·2 per cent hybridised to the DNA probe encoding specific EHEC sequences, and 95·9 per cent showed homology with a 23 kb DNA fragment common to EHEC and SPEC plasmids.