Human uropathogenic and bovine septicaemic Escherichia coli strains carry an identical F17-related adhesin.

Pathogenic Escherichia coli produce fimbriae which mediate binding to mucosal cells. Generally, different fimbriae are associated with different tissular tropisms and different host specificities. Genes encoding for pilin and adhesin subunits of two F17-related fimbriae were cloned and sequenced. The first, G fimbriae, are synthesized by a human uropathogenic E. coli strain, and the second, 20K fimbriae, by a bovine septicaemic E. coli strain. We showed that both fimbriae are identical and present a high homology with F17a and F17b fimbriae synthesized by bovine enterotoxigenic E. coli strains. Furthermore, data showed that the G adhesin did not mediate adhesion to human uroepithelial cells, suggesting that it is not responsible for the urinary tropism of the strain and confirming the intestinal tropism specificity of F17-related adhesins.