Determination of Adhesion Encoding Genes of Uropathogenic Escherichia coli

Abstract

BackgroundUropathogenic Escherichia coli (UPEC), the causative agent of urinary tract infections (UTIs) in otherwise healthy individuals, is a frequently encountered pathogen (1). The UPEC belongs to a subgroup of extraintestinal pathogenic E. coli's which causes a broad spectrum of conditions including bacteraemia, UTIs, and neonatal meningitis in man and colibacillosis in poultry (2). Eighty percent of acute UTIs is associated with E. coli. The infection initiates when the bacteria adhere to the uroepithelial cell receptors through specific fimbrial adhesins (3). E. coli is part of the normal microbiota of the enteric tract of humans and animals. The mutually beneficial symbiotic association of E. coli with its host helps maintaining normal intestinal homeostasis and promoting the stability of the intestinal microbial flora (4).UTI results in substantial medical costs. UPEC is associated with community acquired UTIs and nosocomial UTIs, as well as with considerable morbidity and mortality worldwide (5). The UPEC ability to cause symptomatic UTIs is dependent on the expression of broad spectrum virulence factors (6). Molecules of adhesion and toxins account for the most important mediators of pathogenicity.UPEC receptor binding protein can be differentiated on the basis of their receptor identifying capabilities. The P-fimbriae which is encoded by the pap operon of E. coli will bind to digalactoside containing receptors (7). Sialic acid containing receptors are those for S-fimbriae which is encoded by sfa operon. Afimbrial adhesin is encoded by afa operon and is associated with recurrent UTIs (8). The virulence factors are helpful in colonization and persistence of bacteria in the urinary tract. Adhesins or Fimbriae, toxins, and siderophore systems are involved in initiation of UTI by colonization to host tissues (9).Extraintestinal infections causing E. coli expresses mannose resistant adhesins and pap fimbriae is the most common one (10). The pap (pyelonephritis associated pilus) operon mediates galactosyl galactose specific binding to epithelial surfaces of intestine, vagina, urinary tract, and moiety of the P blood group by their tip adhesion molecule (11,12). The S fimbrial adhesins are frequently expressed in E. coli strains involved in extraintestinal infections (13). The S fimbriae are also mannose resistant and associated with E. coli strains that cause sepsis, meningitis, and ascending UTIs; they help in the bacterial spread within host tissues (14). The E. coli