Multiple Insertional Events, Restricted by the Genetic Background, Have Led to Acquisition of Pathogenicity Island II _J96 -Like Domains among Escherichia coli Strains of Different Clinical Origins

Abstract

We investigated the dissemination of pathogenicity island (PAI) II J96 -like elements (hra, hly, cnf1, and pap) among 455 Escherichia coli isolates from children and adults with urinary tract infection (UTI), neonates with meningitis or colonized healthy neonates, and 74 reference strains by means of PCR phylogenetic grouping, ribotyping, and PCR analysis of virulence genes. Colocalization of these genes was documented by pulsed-field gel electrophoresis followed by Southern hybridization and long-range PCR (LRPCR) between the hra and the papG alleles. Site-specific insertion of the PAI was determined by LRPCR between hra and tRNA flanking sequences. hra, hly, and cnf1 were found in 113 isolates and consistently colocalized, constituting the backbone of PAI II J96 -like domains. The prevalence of PAI II J96 -like domains was significantly higher among UTI isolates than among neonatal meningitis and commensal isolates. These domains were restricted to a few ribotypes of group B2. In contrast to the consistent colocalization of hra, hly, and cnf1, the pap operon was varied: 12% of strains exhibited an allelic exchange of the papG class III allele (papGIII) for the papG class II allele (papGII) (only UTI isolates), and the pap operon was deleted in 23% of strains. No strains harbored papGIII outside the PAI, which appears to be the only source of this allele. PAI II J96 -like domains were inserted in the vicinities of three different tRNAs-pheU (54%), leuX (29%), and pheV (15%)-depending on the genetic backgrounds and origins of the isolates. Multiple insertional events restricted by the genetic background have thus led to PAI II J96 acquisition. Specific genetic backgrounds and insertion sites may have played a role in additional recombination processes for E. coli adaptation to different ecological niches.

Virulence Factors in Urinary Escherichia coli Strains: Phylogenetic Background and Quinolone and Fluoroquinolone Resistance

“…We also confirmed previous knowledge about the genes mostly present in all isolates (fimA), those nearly absent both in non-B2 isolates and in resistant isolates (hlyA and cnf1, which show a physical linkage in PAI II J96 ) (4,38,41), and the intermediate percentages of papC presence (8,16,22,23,33,44).…”

The Escherichia coli argW-dsdCXA Genetic Island Is Highly Variable, and E. coli K1 Strains Commonly Possess Two Copies of dsdCXA

“…Because of the general genetic content of prf fimbrial and hlyCABD virulence genes, this island has also been identified as PAI I C5 and PAI II J96 (5,8,22). The prf fimbria-and hlyCABD-containing island does vary in significant ways because the dsdCXA, hra, and cnf-1 loci are not consistently present.…”

Distribution Pattern of EcoR Phylogenetic Groups Among Shiga Toxin-Producing and Enteropathogenic Escherichia coli Isolated From Healthy Goats

“…Bidet et al (6) categorized their STEC isolates, like O157:H7, into group D and showed that cattle are the main reservoir. There are few studies about the phylogenetic affiliation of STEC and EPEC strains isolated from goats.…”

“…Phylogenetic analysis have indicated that E. coli can be categorized into four major phylogenetic groups (A, B1, B2, and D) which can be divided into seven subgroups A 0 , A 1 , B1, B2 2 , B2 3 , D 1 and, D 2 using a rapid polymerase chain reaction (PCR)-based method for the detection of chuA (the outer-membrane hemin receptor gene), yjaA (the gene encodes an uncharacterized protein) and TSPE4.C2 (an anonymous DNA fragment) (2)(3)(4)(5). Recently, relationships have been demonstrated between E. coli phylogenetic characteristics and obtaining virulence genes (6,7). Virulence factors may be found more commonly in strains of groups B2 and D, whereas majority of A and B1 strains are nonpathogenic and isolated from nondiarrheic fecal samples (8)(9)(10).…”