The role of P fimbriae for colonization and host response induction in the human urinary tract.

Abstract

Bacterial attachment is thought to enhance virulence by promoting colonization of the urinary tract and by attacking tissue [1]. Uropathogenic Escherichia coli express several classes of fimbriae-associated adhesins that mediate attachment through specific binding to different glycoconjugate receptors [2] (for review see Mirelman [3]). P fimbriae, encoded by the pap gene cluster, show the most clear-cut association with virulence as defined by acute disease severity [4]. It has been proposed that P fimbriae augment the virulence of uropathogenic E. coli at different stages during the pathogenesis of urinary tract infection (UTI). pap+ strains remain longer in the intestinal flora and spread more efficiently to the urinary tract than do papstrains [5]. Once in the urinary tract, P-fimbriated strains establish bacteriuria and may cross the epithelial barrier into the bloodstream [6]. P fimbriae enhance epithelial cytokine responses in vitro [7] and in the mouse UTI model [8]. The role of P fimbriae per se for colonization and host response induction is not clear and has been the subject of some discussion. While fimbriae-mediated attachment enhances bac-