Gene typing of the colonisation factors F18 of Escherichia coli isolated from piglets suffering from post-weaning oedema disease

Production of verotoxin Stx2e and expression of F18 and K88 colonisation factors were investigated in 222 strains of Escherichia coli isolated from weaned piglets. Sixty-two, 30, and 11 of the 129 verotoxigenic strains were classified to the serogroups O139, O141, and O157, respectively. Other serogroups were identified only sporadically and sixteen strains were unclassifiable. No colonisation factors were detectable in 15 (24.2%) of the 62 verotoxigenic strains classified with the serogroup O139. The fedA gene shared by the colonisation factors F18 was detected by PCR in 47 of the O139 strains (all but one F18ab). Gene fedA, in which the amplification product was digested with endonuclease NgoMI (F18ac), was peculiar to the serogroup O141. No colonisation factors were detected in 19 (14.7%) strains. Genes encoding the colonisation factors F18ac and F18ab were demonstrated in 22 (23.7%) and 11 (11.8%), of the 93 non-verotoxigenic and mostly enterotoxigenic strains, respectively.