What Makes<i>Escherichia coli</i>Pathogenic?

Siitonen, Anja

doi:10.3109/07853899409147895

Cited by 21 publications

(14 citation statements)

References 27 publications

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“…Of note, papG allele III is epidemiologically associated with cystitis in humans (10, 19) but has not been well evaluated for its contribution to bladder colonization (48) or explored as a vaccine target for the prevention of cystitis. S and F1C fimbriae (sfa/foc) have received little attention as possible contributors to urovirulence (31,32), and S fimbriae in particular have been regarded as pathogenetically relevant principally in neonatal meningitis (43). The in vivo experimental evidence for hemolysin as a urovirulence factor is positive but quite limited (36).…”

Section: Discussionmentioning

confidence: 99%

Identification of Urovirulence Traits inEscherichia coliby Comparison of Urinary and RectalE. coliIsolates from Dogs with Urinary Tract Infection

Johnson¹,

Kaster²,

Kuskowski

et al. 2003

J Clin Microbiol

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Spontaneously occurring urinary tract infection (UTI) in dogs was exploited as an experiment of nature to gain insights into UTI pathogenesis in humans. Concurrent urinary and rectal Escherichia coli isolates from 37 dogs with UTI were compared with respect to phylogenetic background, O antigens, and extended virulence genotype. In 54% of the UTI episodes, the dog's urinary and rectal isolates represented the same strain. Urinary isolates differed dramatically from rectal-only isolates in that they derived predominantly from E. coli phylogenetic group B2, expressed typical (human) UTI-associated O antigens, and possessed many virulenceassociated genes, most notably pap elements (P fimbriae), papG (adhesin) allele III, sfa/foc and sfaS (S fimbriae), hly (hemolysin), fyuA (yersiniabactin), iroN (siderophore), and ompT (outer membrane protease T). The 20 urinary isolates that corresponded with the host's predominant rectal strain were no less virulent according to the markers analyzed than were the 17 urinary isolates that differed from the host's predominant rectal strain. These findings suggest that UTI pathogenesis is similar in dogs and humans, provide added support for the special-pathogenicity over the prevalence hypothesis of UTI pathogenesis, and identify numerous specific virulence-associated factors as significant correlates of urovirulence. Dogs spontaneously develop urinary tract infection (UTI)due to strains of Escherichia coli similar to those that cause UTI in humans (4, 6, 7, 15, 18, 25, 30, 42, 45-47, 50, 51). In both host groups, the urinary pathogens typically derive from specific clonal groups within virulence-associated E. coli phylogenetic group B2, express one of several UTI-associated O antigens, and possess specialized virulence-associated factors (VFs) that directly contribute to, or are markers for, an enhanced ability to overcome host defenses and cause extraintestinal disease (15,18,25,41). In both dogs (18, 30) and humans (8,40,49) at the time of a UTI episode, the infecting urinary strain is often the host's predominant rectal E. coli strain, consistent with the fecal reservoir as the proximate source from which pathogens enter the urinary tract. Even healthy dogs are frequently intestinally colonized with uropathogenic E. coli and shed these organisms in their feces (23,50,51).These observations are potentially relevant to human health because they suggest that dogs may pose an infectious threat to humans by providing a reservoir of "human" uropathogenic E. coli for acquisition by susceptible human hosts (15,18,23,25,30,45). In addition, they suggest that the pathogenesis of UTI is similar in dogs and humans, so that dogs might serve as a pathogenetically relevant model system for observational or experimental studies of UTI pathogenesis (15,25).Accordingly, in the present study we took advantage of spontaneously occurring UTI in dogs to address several questions regarding the pathogenesis of UTI in humans. In 37 dogs with UTI, which served as their own controls, we compared concurre...

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Section: Discussionmentioning

confidence: 99%

Identification of Urovirulence Traits inEscherichia coliby Comparison of Urinary and RectalE. coliIsolates from Dogs with Urinary Tract Infection

Johnson¹,

Kaster²,

Kuskowski

et al. 2003

J Clin Microbiol

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“…For example, can elevated coliform counts be attributed to human or animalderived faecal contamination, or can the geographical source of the contamination be identified? Much of this work focuses on Escherichia coli, as it is the dominant member of the aerobic flora of most humans and the cause of a significant fraction of human bacterial disease (Siitonen, 1994 ;Leclerc et al, 2001 D. M. Gordon, S. Bauer and J. R. Johnson Savageau (1983) observed that the life cycle of enteric bacteria such as E. coli involves a transition between two distinct environments. He considered the primary habitat of E. coli to be the gastrointestinal tract of mammals, whilst soil, water and sediment represents the species' secondary habitat.…”

Section: Abbreviationsmentioning

confidence: 99%

The genetic structure of Escherichia coli populations in primary and secondary habitats

2002

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Escherichia coli were recovered from the members of two two-person households and their associated septic tanks. The E. coli were isolated using selective and non-selective isolation techniques, characterized using the method of multi-locus enzyme electrophoresis and screened for the presence of virulence factors associated with extra-intestinal disease by using PCR. The growth rate-temperature relationships of strains from the two habitats were also determined. Temporal variation explained 25 % of the observed electrophoretic type (ET) diversity in the humans. Among-host variation accounted for 29 % of the observed allelic diversity. In one household, ET diversity of the E. coli population in the septic tank was significantly lower than ET diversity in the humans providing the inputs to the septic tank. Molecular analysis of variance revealed that, on average, strains recovered from the septic tank of this household were genetically distinct from strains recovered from the humans providing the faecal inputs to the septic tank. Further, the growth rate-temperature response of strains differed between strains isolated from the septic tank and strains isolated from the humans. Septic tank isolates grew better at low temperatures than strains isolated from humans, but more slowly at high temperatures compared to the human isolates. By contrast, no real differences in ET diversity, allelic diversity, or the growth charcteristics of strains could be detected between strains from the humans and strains from the septic tank of the other household. The results of this study suggest there are strains of E. coli that are better ' adapted ' to conditions found in the external environment compared to strains isolated from the gastrointestinal habitat. Further, the finding that the numerically dominant clones and clonal diversity in secondary habitats can differ substantially from those found in the source populations will confound efforts to identify the sources of faecal pollution in the environment.

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“…For example, can elevated coliform counts be attributed to humanderived or animal-derived faecal contamination, or can the geographical source of the contamination be identified? Much of this work focuses on E. coli, as it is the dominant member of the aerobic flora of humans and the cause of a significant fraction of human bacterial disease (Siitonen, 1994). The techniques in use include examining antibiotic resistance profiles and genotyping bacteria using ribotyping or PCR-based methods such as rep-PCR (Parveen et al, 1997(Parveen et al, , 1999Dombek et al, 2000).…”

Section: Tracing the Source Of Environmental E Coli Contaminationmentioning

confidence: 99%

Geographical structure and host specificity in bacteria and the implications for tracing the source of coliform contamination

2001

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OverviewThis mini-review presents the results of recent studies examining the extent to which among-population variation accounts for the genetic diversity of Escherichia coli and other members of the Enterobacteriaceae. The available population genetic data for E. coli are discussed in relation to an issue perceived to be of public health importance -the coliform contamination of water and efforts to trace the source of such contamination. For E. coli, the data suggest that geographical structure or host specificity accounts for little of the observed genetic diversity. Furthermore, the evidence indicates that there is little temporal stability in the clonal composition of E. coli populations. Consequently, most of the assumptions implicit in any programme attempting to identify the source of coliform contamination that focuses on commensal isolates of E. coli appear to be invalid. Other species of enteric bacteria appear to exhibit greater host specificity and geographical structure. The results of recent studies concerning the distribution of virulence factors among the clonal lineages of E. coli are highlighted and discussed in regard to alternative strategies for tracing the source of coliform contamination.

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What MakesEscherichia coliPathogenic?

Cited by 21 publications

References 27 publications

Identification of Urovirulence Traits inEscherichia coliby Comparison of Urinary and RectalE. coliIsolates from Dogs with Urinary Tract Infection

Identification of Urovirulence Traits inEscherichia coliby Comparison of Urinary and RectalE. coliIsolates from Dogs with Urinary Tract Infection

The genetic structure of Escherichia coli populations in primary and secondary habitats

Geographical structure and host specificity in bacteria and the implications for tracing the source of coliform contamination

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