ADHESINS OF ESCHERICHIA-COLI ASSOCIATED WITH EXTRAINTESTINAL PATHOGENICITY CONFER BINDING TO COLONIC EPITHELIAL-CELLS

Escherichia coli adhesins are virulence factors in intestinal and extr a-intestinal infections, but their role in normal intestinal colonizat ion has not been defined. We investigated the intestinal adherence of E. coli with Dr hemagglutinin, S fimbriae, CFA/I or CFA/II, using fres hly isolated ileal or colonic enterocytes and cells from the human col onic cell line HT-29. E. coli with S-fimbrial adhesins (Sfa I or Sfa I I), P or type 1 fimbriae, adhered in a non-polarized manner, and in si milar numbers to colonic and ileal enterocytes. S fimbriae of the vari ety Sfa II (originating from a meningitis isolate), mediated a stronge r binding than Sfa I (of uropathogenic origin). Strains expressing Dr hemagglutinin adhered preferentially to the brush borders, slightly be tter to colonic than ileal enterocytes. Strains expressing CFA/I or II adhered to colonic and ileal enterocytes, although brush border adher ence was predominantly observed with ileal cells. Binding to HT-29 cel ls parallelled binding to colonic enterocytes for all adhesin specific ities except CFA/I. The results suggest that Dr hemagglutinin, P-, typ e 1- and S-fimbrial adhesins mediate binding to both colonic and ileal enterocytes. These specificities may contribute to the establishment of E. coli in the intestinal microflora, which precedes their spread t o extra-intestinal sites.