Adhesins ofEscherichia coliassociated with extra–intestinal pathogenicity confer binding to colonic epithelial cells

Abstract

Escherichia coliadhesins are virulence factors in intestinal and extra–intestinal infections but their role in normal intestinal colonization has not been defined. We investigated the intestinal adherence ofE. coliwith Dr hemagglutinin S fimbriae CFA/I or CFA/II using freshly isolated ileal or colonic enterocytes and cells from the human colonic cell line HT–29.E. coliwith S–fimbrial adhesins (Sfa I or Sfa II) P or type 1 fimbriae adhered in a non–polarized manner and in similar numbers to colonic and ileal enterocytes. S fimbriae of the variety Sfa II (originating from a meningitis isolate) mediated a stronger binding than Sfa I (of uropathogenic origin). Strains expressing Dr hemagglutinin adhered preferentially to the brush borders slightly better to colonic than ileal enterocytes. Strains expressing CFA/I or II adhered to colonic and ileal enterocytes although brush border adherence was predominantly observed with ileal cells. Binding to HT–29 cells parallelled binding to colonic enterocytes for all adhesin specificities except CFA/I. The results suggest that Dr hemagglutinin P– type 1– and S–fimbrial adhesins mediate binding to both colonic and ileal enterocytes. These specificities may contribute to the establishment ofE. coliin the intestinal microflora which precedes their spread to extra–intestinal sites.