Uropathogenic Escherichia coli

Abstract

Uropathogenic Escherichia coli (UPEC) strains are responsible for the majority of uncomplicated urinary tract infections, which can present clinically as cystitis or pyelonephritis. UPEC strain CFT073, isolated from the blood of a patient with acute pyelonephritis, was most cytotoxic and most virulent in mice among our strain collection. Based on the genome sequence of CFT073, microarrays were utilized in comparative genomic hybridization (CGH) analysis of a panel of uropathogenic and fecal/commensal E. coli isolates. Genomic DNA from seven UPEC (three pyelonephritis and four cystitis) isolates and three fecal/commensal strains, including K-12 MG1655, was hybridized to the CFT073 microarray. The CFT073 genome contains 5,379 genes; CGH analysis revealed that 2,820 (52.4%) of these genes were common to all 11 E. coli strains, yet only 173 UPEC-specific genes were found by CGH to be present in all UPEC strains but in none of the fecal/commensal strains. When the sequences of three additional sequenced UPEC strains (UTI89, 536, and F11) and a commensal strain (HS) were added to the analysis, 131 genes present in all UPEC strains but in no fecal/commensal strains were identified. Seven previously unrecognized genomic islands (>30 kb) were delineated by CGH in addition to the three known pathogenicity islands. These genomic islands comprise 672 kb of the 5,231-kb (12.8%) genome, demonstrating the importance of horizontal transfer for UPEC and the mosaic structure of the genome. UPEC strains contain a greater number of iron acquisition systems than do fecal/commensal strains, which is reflective of the adaptation to the iron-limiting urinary tract environment. Each strain displayed distinct differences in the number and type of known virulence factors. The large number of hypothetical genes in the CFT073 genome, especially those shown to be UPEC specific, strongly suggests that many urovirulence factors remain uncharacterized.Escherichia coli strains capable of causing disease outside the gastrointestinal tract belong to a diverse group of isolates referred to as extraintestinal pathogenic E. coli (ExPEC) (50, 84). ExPEC strains are responsible for a variety of diseases, including urinary tract infections (UTIs), newborn meningitis, septicemia, nosocomial pneumonia, intra-abdominal infections, osteomyelitis and wound infections (22,27,49,84). Uropathogenic E. coli (UPEC), a prominent member of the ExPEC family, is responsible for up to 90% of uncomplicated UTIs in otherwise healthy individuals (108). An infection occurs primarily by the ascending route following the contamination of the periurethral area, presumably via a fecal reservoir. Bacteria ascend the urethra and colonize the bladder, resulting in cystitis, and in severe cases, infection may spread up the ureters to the kidneys, causing pyelonephritis (15). A serious and potentially life-threatening complication of pyelonephritis occurs when bacteria invade the bloodstream and produce a systemic infection. Due to anatomical differences, UTIs are significantly mo...

Characterization of 17 chaperone-usher fimbriae encoded by Proteus mirabilis reveals strong conservation

“…Instead, it may be possible that while most of these fimbriae are ubiquitous in P. mirabilis , amino acid variations within a given fimbria confer an advantage in specific environments. This phenomenon has already been observed for the type I fimbria, which is present in the vast majority of E. coli isolates (Mobley et al , 2009). Specific amino acid sequences of the FimH adhesin are more likely to be found in uropathogenic E. coli compared with faecal E. coli , and these variations alter binding characteristics (Sokurenko et al , 1995, 1998).…”

Presence of Putative Repeat-in-Toxin Gene tosA in Escherichia coli Predicts Successful Colonization of the Urinary Tract

“…In contrast, papA (coding for the structural subunit of pyelonephritis-associated pili), although less prevalent overall (56.5%), was significantly more prevalent among all urine isolates combined (59.2%) than among fecal isolates (26.4%) ( P < 0.0001). Both of these findings are in general agreement with results from previous studies ( 4 ).…”

“…The infection may be confined to the bladder, or bacteria may ascend the ureters to infect the kidneys causing pyelonephritis. In severe cases, bacteria can further disseminate across the proximal tubular epithelium and capillary endothelium to the bloodstream, causing bacteremia ( 4 ). A significant proportion of UTIs occur in patients with no known abnormalities of the urinary tract, so-called “uncomplicated UTIs.” However, certain host characteristics, such as the presence of an indwelling Foley catheter or congenital defect in urinary tract anatomy, are considered complicating factors for UTI, and increase susceptibility to this infection, as well as affecting diagnosis and management ( 5 ).…”

Host–pathogen interactions in urinary tract infection

“…Uropathogenic E. coli are a specific subset of extraintestinal pathogenic E. coli; that is, not all strains of E. coli are capable of causing UTI. 9 By contrast, it appears that all strains of P. mirabilis, regard less of isolate origin, are capable of infecting the urinary tract. 10 Prototypical strains of each pathogen have been sequenced: E. coli strains CFT073, 11 536, 12 UTI89, 13 IAI 39, 14 and Umn026, 14 and P. mirabilis strain HI4320.…”