Differentiation of verotoxigenic strains of Escherichia coli isolated frompiglets and calves in the Czech Republic

A set of 451 and 115 strains of Escherichia coli isolated from piglets and calves affected by diarrhoea, respectively, were tested for verotoxin produ ction and type. The production was tested on Vero cells and the type was id entified by PCR. The production of verotoxin was demonstrated in 189 of the porcine strains and 13 of the bovine strains. Most of the porcine verotoxi genic strains belonged to the serogroups O139, O141, O157, and O138. Positi ve for verotoxin production were 83.3% and 78.2% of the strains of the sero groups O139 and O141, respectively. The type VT2e was identified in 184 str ains and a sequence corresponding to VT2c was found in 2 strains. However, the latter yielded negative results in the Vero cells test. Furthermore an unidentified toxin type was demonstrated in three strains positive in the V ero cell culture. The bovine verotoxigenic strains belonged to the serogrou ps O20, O26, O103, O111, and O157. Both VT1 and VT2 were produced by 6 (46. 2%) of the 13 verotoxigenic strains. Only one verotoxin type was produced b y each of the remaining verotoxigenic strains.