Adhesive and invasive factors of uropathogenic Escherichia coli strains -: urinary tract infections and mechanisms of pathogenesis

The urinary tract is a common site of bacterial infection, and Escherichia coli is by far the most common infecting agent at this site (80%). Surface virulence factors of pathogenic bacteria include various adhesive polymeric structures (pili/fimbriae) responsible for the recognition of specific cellular receptors. The interaction between adhesin and the selected receptor is a crucial step in pathogenesis. The most common adhesive structures of E. coli are type I pili and type P pili causing cystitis and pyelonephritis, respectively. The third group of E. coli adhesive factors (30-50% of cases of cystitis and 30% of cases of pyelonephritis in pregnant women and diarrhoea in infants) are adhesins belonging to the Dr family. The members of this family of adhesins are able to bind to human-decay accelerating factor (DAF) on the surface of urinary epithelial cells and promote DAF mobilization. The physiologic agent which enables a colonization of urinary tract by E. coli in pregnant women is the pregnancy. Pyelonephritis in pregnant women is a serious complication leading to bacteremia, urosepsis, acute respiratory distress syndrome and even death. The course of the pregnancy may be affected and may result in preterm labor and intrauterine growth retardation. The biogenesis of the adhesive polymeric structures is highly conserved among Gram-negative bacteria. Recently, compounds that inhibit pilus biogenesis and interfere with chaperone-subunit interactions have been discovered and termed pilicides. The pilicides target key virulence factors in pathogenic bacteria and thus are a promising cobdidate for developing drugs that would function by targeting virulence factors.