Pathogenicity island sequences of pyelonephritogenic Escherichia coli CFT073 are associated with virulent uropathogenic strains

Abstract

Urinary tract infection is the most frequently diagnosed kidney and urologic disease, and Escherichia coli is by far the most common etiologic agent. Defined blocks of DNA termed pathogenicity islands have been found in uropathogenic strains to carry genes not generally found in fecal strains. We have identified one of these regions of DNA within the chromosome of the highly virulent E. coli CFT073, isolated from the blood and urine of a woman with acute pyelonephritis. This strain, which is cytotoxic for cultured renal cells and causes acute pyelonephritis in transurethrally infected CBA mice, contains two distinct copies of the pap operon and is hemolytic. One pap operon was localized on a cosmid clone which was used to identify three overlapping cosmid clones. By using restriction mapping, DNA hybridization, sequencing, and PCR amplification, a region of approximately 50 kb was found to be present in this uropathogenic strain and to have no corresponding sequences in E. coli K-12. This gene block also carries hemolysin genes hlyCABD. The pathogenicity island begins 7 bp downstream of dadX (catabolic alanine racemase; 26.55 min) and ends at a position in the K-12 genome 75 bp downstream of the metV tRNA gene (62.74 min); this suggests that a chromosomal rearrangement has occurred relative to the K-12 linkage map. The junctions of the pathogenicity island were verified by PCR amplification directly from the genomic DNA of strain CFT073. DNA sequencing within the boundaries of the junctions revealed genes not previously identified in E. coli or in some cases bearing no known homologs. When used as probes for DNA hybridization, these sequences were found significantly more often in strains associated with the clinical syndromes of cystitis (82%) and acute pyelonephritis (79%) than in fecal strains (19%; P < 0.001).

Distribution of Open Reading Frames of Plasticity Region of Strain J99 in Helicobacter pylori Strains Isolated from Gastric Carcinoma and Gastritis Patients in Costa Rica

“…In this study, we show, for the first time, that 20 selected plasticity region ORFs may also be present in other H. pylori strains. This is an important point, because among these genes, 16 were previously classed as J99 specific based solely on the comparison between the J99 and 26695 strains. Furthermore, the ends of the plasticity zone were defined only by the comparison of these two strains, and they were therefore not precise.…”

“…Environment-, host-, and strain-dependent factors could play a role in the evolution of the infection. Similarly to other bacterial pathogens which present pathogenic and nonpathogenic variants of the same species, such as uropathogenic (16,28) and enteropathogenic (22) Escherichia coli, Salmonella enterica serovar Typhimurium (11,23), and highly pathogenic Yersinia species (4,25), H. pylori strains isolated from patients suffering from the most severe gastric diseases possess a pathogenicity island in their genome named the cag pathogenicity island (1,6,7,15,19). The term "pathogenicity island" is used to indicate the presence of a large chromosomal segment (30 kb or more in size) containing a cluster of virulence genes and presenting several characteristics suggesting a possible origin by horizontal transfer from another bacterial species, such as a GϩC content different from that of the rest of the genome, the presence of repeated sequences, and a possible insertion within tRNA genes (10,11).…”

Molecular characterization of extraintestinal pathogenic (ExPEC) pathogenicity islands in F165-positive strain from a diseased animal

“…Pulsed-field gel electrophoresis (PFGE) was used to determine the physical locations of genes representative of PAI-like genetic elements [6,25]. DNA from E. coli strain 4787 digested by XbaI and NotI were subjected to PFGE.…”

Absence of ZnuABC-mediated zinc uptake affects virulence-associated phenotypes of uropathogenicEscherichia coli CFT073 under Zn(II)-depleted conditions

“…Both pathogenic and nonpathogenic E. coli have evolved through a complex process so that only about 39% of genes have a common ancestor (Welch et al, 2002). Most of the other genes are newly acquired via horizontal gene transfer events (Kao et al, 1997). Uropathogenic E. coli (UPEC) are uniquely endowed with various virulence traits, enabling them to survive and grow in urine and other extraintestinal environments.…”