Clonal relationships and extended virulence genotypes among Escherichia coli isolates from women with a first or recurrent episode of cystitis.

To identify bacterial predictors of recurrence and/or persistence in acute cystitis, extended virulence genotypes were compared with clonal background and epidemiologic status among 74 Escherichia coli urine isolates from women with first or recurrent episodes of urinary tract infection (UTI). Sequential isolates from patients with recurrent UTI were classified, using macrorestriction analysis, as having caused an isolated recurrence versus a single or multiple same-strain recurrences. papA, papG allele II, iha, and iutA predicted multiple same-strain recurrences, whereas nfaE and the absence of sfaS or fyuA predicted isolated recurrences. Phylogenetic group B2 accounted for 70% of isolates and for most of the putative virulence factors (VFs) studied. The meningitis-associated O18:K1:H7 clonal group comprised 18% of isolates, exhibited multiple VFs, and caused "once-only" recurrences less commonly than did other strains. These findings identify specific VFs and clonal groups against which preventive interventions might be beneficial and illustrate the importance of delineating pathogenetically relevant subgroups within the "recurrent cystitis" population.

Phylogenetic and pathotypic similarities between Escherichia coli isolates from urinary tract infections in dogs and extraintestinal infections in humans.

Seventeen Escherichia coli isolates from dogs with urinary tract infection (UTI) were characterized with respect to phylogenetic background and virulence genotype and were compared with the E. coli reference (ECOR) collection and with human clinical isolates with similar serotypes from patients with diverse extraintestinal infections. Most of the canine urine isolates were from (virulence-associated) E. coli phylogenetic groups B2 or D, expressed papG allele III, and exhibited numerous other putative virulence genes that are characteristic of human extraintestinal pathogenic E. coli (ExPEC). Close phylogenetic and pathotypic correspondence was documented within 5 clonal groups among individual canine and human isolates, including archetypal human ExPEC strains CFT073 (O6:K2:H1), 536 (O6:K15:H31), and J96 (O4:K-:H5). These findings suggest that canine UTI isolates, rather than being dog-specific pathogens, as previously suspected, may pose an infectious threat to humans. Commonality between canine and human ExPEC has potentially important implications for disease prevention, antibiotic resistance avoidance, and studies of pathogenesis.

Canine feces as a reservoir of extraintestinal pathogenic Escherichia coli.

To test the canine reservoir hypothesis of extraintestinal pathogenic Escherichia coli (ExPEC), 63 environmental canine fecal deposits were evaluated for the presence of ExPEC by a combination of selective culturing, extended virulence genotyping, hemagglutination testing, O serotyping, and PCR-based phylotyping. Overall, 30% of canine fecal samples (56% of those that yielded viable E. coli) contained papG-positive E. coli, usually as the predominant E. coli strain and always possessing papG allele III (which encodes variant III of the P-fimbrial adhesin molecule PapG). Multiple other virulence-associated genes typical of human ExPEC were prevalent among the canine fecal isolates. According to serotyping, virulence genotyping, and random amplified polymorphic DNA analysis, over 50% of papG-positive fecal E. coli could be directly correlated with specific human clinical isolates from patients with cystitis, pyelonephritis, bacteremia, or meningitis, including archetypal human ExPEC strains 536, CP9, and RS218. Five canine fecal isolates and (clonally related) archetypal human pyelonephritis isolate 536 were found to share a novel allele of papA (which encodes the P-fimbrial structural subunit PapA). These data confirm that ExPEC representing known virulent clones are highly prevalent in canine feces, which consequently may provide a reservoir of ExPEC for acquisition by humans.

Escherichia coli O18:K1:H7 isolates from patients with acute cystitis and neonatal meningitis exhibit common phylogenetic origins and virulence factor profiles.

Escherichia coli isolates of serotype O18:K1:H7, taken from women with acute cystitis, healthy control patients, and infants with neonatal bacterial meningitis (NBM), were analyzed and were compared with phylogenetically diverse control strains from the E. coli Reference collection. Clonal relationships were defined by amplification phylotyping, nicotinamide auxotrophy, and outer membrane protein patterns (OMPs). Virulence factor profiles were determined by multiplex polymerase chain reaction, probe hybridization, and hemagglutination testing. The O18:K1:H7 cystitis, fecal, and NBM isolates were clonally derived. The cystitis isolates and archetypal NBM isolates RS218 and C5 were from the OMP6 subclone of E. coli O18:K1:H7 and exhibited a consensus virulence genotype that included papG allele III (cystitis-associated P fimbrial adhesin), sfaS (S fimbrial adhesin), hlyA (hemolysin), cnf1 (cytotoxic necrotizing factor), iroN (putative siderophore), and ibeA (invasion of brain endothelium). The demonstrated commonality between O18:K1:H7 isolates from cystitis and NBM suggests common pathogenetic mechanisms and the possibility of new approaches to prevention.

Phylogenetic distribution of extraintestinal virulence-associated traits in Escherichia coli.

The 72 member strains of the Escherichia coli Reference collection were assessed as to genotype for 31 putative extraintestinal virulence factor (VF) genes and DNA sequence for papA, the P fimbrial structural subunit gene. Although most VFs were concentrated in phylogenetic group B2 or jointly in groups B2 and D, others were concentrated primarily in group D, were broadly distributed (without group-specific associations), and/or occurred only outside of group B2. Statistical correlations among VFs suggested linkage on pathogenicity-associated islands or plasmids. Isolates from humans and nonhuman primates had more VFs than did isolates from other animals. Sequence diversity was minimal within each F type-specific papA allele group but was substantial among different papA allele groups. The distribution patterns of papA variants and other VFs suggested multiple horizontal transfer events. These findings provide new insights into the phylogenetic origins of extraintestinal VFs in E. coli.

Molecular comparison of extraintestinal Escherichia coli isolates of the same electrophoretic lineages from humans and domestic animals.

Molecular typing methods were used to characterize 38 Escherichia coli strains that originally were isolated from extraintestinal infections and represented 5 multilocus enzyme electrophoretic types (ETs) recovered from both humans and animals. Within each ET, the human and animal isolates did not consistently segregate by host group, according to individual virulence factors (VFs), composite VF-serotype profiles, or pulsed-field gel electrophoresis profiles. Several close matches with respect to VF-serotype profiles were identified between human and canine isolates from different locales. One canine and 2 human isolates of serogroup O6 closely resembled archetypal human pyelonephritis isolate 536 (O6:K15:H31), according to papA sequence and VF-serotype profile. These findings support the hypothesis that certain pathogenic lineages of E. coli cause disease in both humans and animals and that humans may acquire pathogenic E. coli from domestic pets.

Evidence of commonality between canine and human extraintestinal pathogenic Escherichia coli strains that express papG allele III.

Although dogs have been proposed as carriers of extraintestinal pathogenic Escherichia coli (ExPEC) with infectious potential for humans, presumed host species-specific differences between canine and human ExPEC strains have cast doubt on this hypothesis. The recent discovery that allele III of papG (the P fimbrial adhesin gene) predominates among human cystitis isolates and confers an adherence phenotype resembling that of canine ExPEC prompted the present reevaluation of the canine-human ExPEC connection. Sixteen paired pap-positive urine and rectal E. coli isolates from dogs with urinary tract infection were studied. papG (adhesin) and papA (pilin) allele type, agglutination phenotypes, virulence factor genotypes, and randomly amplified polymorphic DNA and pulsed-field gel electrophoresis fingerprints were analyzed and compared with those of human ExPEC controls. The 16 canine strains contained predominantly papG allele III. Agglutination phenotypes segregated strictly according to papG allele status and were homogeneous among strains with the same papG allele profile irrespective of their human versus canine origin. Canine and human PapG variant III peptide sequences were highly homologous, without host species-specific differences. The most prevalent canine papA allele was F48, a novel variant recently identified among human urosepsis isolates. In addition to pap, human ExPEC-associated virulence genes detected among the canine strains included sfa/focDE, sfaS, fyuA, hlyA, cnf1, cdtB, kpsMT-II and -III, rfc, traT, ompT, and a marker for a pathogenicity-associated island from archetypal human ExPEC strain CFT073. Molecular fingerprinting confirmed the fecal origin of all but one canine urine isolate and showed one pair of O6 canine urine and fecal isolates to be extremely similar to an O6 human urosepsis isolate with which they shared all other genotypic and phenotypic characteristics analyzed. These data demonstrate that canine ExPEC strains are similar to, and in some instances essentially indistinguishable from, human ExPEC strains, which implicates dogs and their feces as potential reservoirs of E. coli with infectious potential for humans.

Activities of a nitrofurazone-containing urinary catheter and a silver hydrogel catheter against multidrug-resistant bacteria characteristic of catheter-associated urinary tract infection.

The in vitro inhibitory activity of a nitrofurazone-coated urinary catheter (NFC) against 86 recently obtained susceptible and multidrug-resistant (MDR) clinical isolates of Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Staphylococcus aureus, coagulase-negative staphylococci, and Enterococcus faecium, which are species implicated in catheter-associated urinary tract infection and which traditionally have been susceptible to nitrofuran derivatives, was determined using an agar diffusion assay. In a subset of these strains, the activity of the NFC was compared with that of a silver hydrogel urinary catheter (SHC), and the durability of each catheter's inhibitory activity was assessed during serial daily transfers of catheter segments to fresh culture plates. Except for vancomycin-resistant E. faecium, the NFC was active against all isolates tested and showed comparable inhibition zones with susceptible and MDR strains of each species. In contrast, the SHC inhibited only certain staphylococci (P < 0.01 versus the NFC), and among these strains, the SHC produced smaller inhibition zones than did the NFC (P < 0.01). Inhibition was evident for up to 5 days with the NFC, but for only 1 day (if at all) with the SHC (P < 0.01). These data document that, for most genera which traditionally have been susceptible to nitrofuran derivatives, the NFC remains active against contemporary MDR isolates. They also demonstrate that the in vitro antibacterial activity of the NFC is markedly superior to that of the SHC in several respects. Thus, the NFC shows promise for clinical use in the current era of MDR bacteria.