Occurrence of verotoxin (Shiga-like toxin) producingEscherichia coli in human urinary tract infection

Beutin, Lothar; Karch, Helge; Aleksic, S.; Spencker, F.-B.; Rosenbaum, Ute

doi:10.1007/bf01715504

Cited by 9 publications

(6 citation statements)

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“…Despite the fact that the frequency of UTIs caused by IPEC appears to be quite low (58,(66)(67)(68)(69), our results indicate that E. coli-associated UTIs may be caused by a diverse group of E. coli variants, some of which represent STEC, aEPEC, and EAEC, or heteropathogenic strains that combine IPEC and ExPEC virulence traits. The ability of such organisms to colonize the host and cause infection is not only dependent on their virulence-associated traits but also on risk factors that are highly relevant to infections in hospital patients, such as immunosuppression, underlying diseases, age, and long-term indwelling catheterization (23,(70)(71)(72).…”

Section: Discussioncontrasting

confidence: 54%

Characterization of Escherichia coli Isolates from Hospital Inpatients or Outpatients with Urinary Tract Infection

et al. 2014

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e Uropathogenic Escherichia coli (UPEC) is the most common cause of community-and hospital-acquired urinary tract infections (UTIs). Isolates from uncomplicated community-acquired UTIs express a variety of virulence traits that promote the efficient colonization of the urinary tract. In contrast, nosocomial UTIs can be caused by E. coli strains that differ in their virulence traits from the community-acquired UTI isolates. UPEC virulence markers are used to distinguish these facultative extraintestinal pathogens, which belong to the intestinal flora of many healthy individuals, from intestinal pathogenic E. coli (IPEC). IPEC is a diarrheagenic pathogen with a characteristic virulence gene set that is absent in UPEC. Here, we characterized 265 isolates from patients with UTIs during inpatient or outpatient treatment at a hospital regarding their phylogenies and IPEC or UPEC virulence traits. Interestingly, 28 of these isolates (10.6%) carried typical IPEC virulence genes that are characteristic of enteroaggregative E. coli (EAEC), Shiga toxin-producing E. coli (STEC), and atypical enteropathogenic E. coli (aEPEC), although IPEC is not considered a uropathogen. Twenty-three isolates harbored the astA gene coding for the EAEC heat-stable enterotoxin 1 (EAST1), and most of them carried virulence genes that are characteristic of UPEC and/or EAEC. Our results indicate that UPEC isolates from hospital patients differ from archetypal community-acquired isolates from uncomplicated UTIs by their spectrum of virulence traits. They represent a diverse group, including EAEC, as well as other IPEC pathotypes, which in addition contain typical UPEC virulence genes. The combination of typical extraintestinal pathogenic E. coli (ExPEC) and IPEC virulence determinants in some isolates demonstrates the marked genome plasticity of E. coli and calls for a reevaluation of the strict pathotype classification of EAEC.

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Section: Discussioncontrasting

confidence: 54%

Characterization of Escherichia coli Isolates from Hospital Inpatients or Outpatients with Urinary Tract Infection

et al. 2014

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“…EHEC strains have occasionally been documented to be the causative agents of UTIs in humans (9,(50)(51)(52)(53)(54)(55). Many questions regarding the urovirulence mechanisms and the uropathogenicity of EHEC strains remain unanswered.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, cases of urinary tract infection (UTI) where EHEC isolates have been isolated from the corresponding urine samples have been reported. The first report of EHEC urine isolates was released in 1994 (9). Although the frequency of UTI caused by EHEC seems to be low (10), many questions regarding the virulence potential and pathogenicity of EHEC isolates in the urinary tract still remain unanswered.…”

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Characterization of Urinary Tract Infection-Associated Shiga Toxin-Producing Escherichia coli

et al. 2014

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c Enterohemorrhagic Escherichia coli (EHEC), a subgroup of Shiga toxin (Stx)-producing E. coli (STEC), is a leading cause of diarrhea and hemolytic-uremic syndrome (HUS) in humans. However, urinary tract infections (UTIs) caused by this microorganism but not associated with diarrhea have occasionally been reported. We geno-and phenotypically characterized three EHEC isolates obtained from the urine of hospitalized patients suffering from UTIs. These isolates carried typical EHEC virulence markers and belonged to HUS-associated E. coli (HUSEC) clones, but they lacked virulence markers typical of uropathogenic E. coli. One isolate exhibited a localized adherence (LA)-like pattern on T24 urinary bladder epithelial cells. Since the glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) are well-known receptors for Stx but also for P fimbriae, a major virulence factor of extraintestinal pathogenic E. coli (ExPEC), the expression of Gb3Cer and Gb4Cer by T24 cells and in murine urinary bladder tissue was examined by thin-layer chromatography and mass spectrometry. We provide data indicating that Stxs released by the EHEC isolates bind to Gb3Cer and Gb4Cer isolated from T24 cells, which were susceptible to Stx. All three EHEC isolates expressed stx genes upon growth in urine. Two strains were able to cause UTI in a murine infection model and could not be outcompeted in urine in vitro by typical uropathogenic E. coli isolates. Our results indicate that despite the lack of ExPEC virulence markers, EHEC variants may exhibit in certain suitable hosts, e.g., in hospital patients, a uropathogenic potential. The contribution of EHEC virulence factors to uropathogenesis remains to be further investigated. Escherichia coli is one of the most versatile microorganisms that rapidly colonizes the gastrointestinal tract of newborns (1). Although E. coli usually represents an important commensal of the normal intestinal microbiota, other variants that are able to cause infections exist (1, 2). On the basis of their virulence properties and the site of infection, these bacteria are classified as intestinal pathogenic E. coli (IPEC), which are associated with diarrhea, and extraintestinal pathogenic E. coli (ExPEC), which cause infections beyond the intestinal tract (3). Enterohemorrhagic E. coli (EHEC) belongs to the IPEC group of bacteria and represents one of the main causative agents of diarrhea, hemorrhagic colitis (HC), and hemolytic-uremic syndrome (HUS) in humans (4). The characteristic main EHEC virulence markers include the locus of enterocyte effacement (LEE) pathogenicity island and Shiga toxin (Stx)-encoding bacteriophages. Additionally, other toxins, including the cytolethal distending toxin (CDT), EHEC hemolysin (Hly), serine protease EspP, subtilase cytotoxin, cyclomodulin Cif, and different siderophore systems, as well as adhesins can also contribute to EHEC pathogenesis (5). These EHEC virulence factors are absent from archetypal ExPEC strains.Similarly, the main ExPEC virulence fa...

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“…This mutation in the FimH mannose‐binding pocket in a subset of E. coli O157:H7 might limit the urovirulence potential of those isolates even if the switch configuration permitted the expression of FimH. However, it is notable that EHEC as a group, including those that can express type 1 pili, are almost never found among collections of urinary tract isolates (Beutin et al , 1994; Johnson et al , 2002). Perhaps they have not sustained a variety of pathoadaptive mutations in FimH that enable urovirulence (Sokurenko et al , 1999, 2004; Hommais et al , 2003; Weissman et al , 2006), and have not acquired a sufficient repertoire of additional virulence loci that augment uropathogenicity (Bahrani‐Mougeot & Gunter, 2002; Johnson & Russo, 2004, 2005).…”

Section: Discussionmentioning

confidence: 99%

Fimoperon variation in the emergence of EnterohemorrhagicEscherichia coli: an evolutionary and functional analysis

Shaikh

Holt

Johnson

et al. 2007

FEMS Microbiology Letters

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Fim operons were examined to illuminate the emergence of Escherichia coli O157:H7 from the less-virulent E. coli O55:H7. A fim invertible element deletion occurred only after O157:H7 descended from O55:H7, and after sorbitol nonfermenting O157 diverged. Type 1 pili nonexpression correlates with this deletion in all enterohemorrhagic E. coli (EHEC) tested. An N135K FimH mutation in the two most evolved O157:H7 clusters is not found in other EHEC. These data refine the evolutionary history of an emerging pathogen.

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Occurrence of verotoxin (Shiga-like toxin) producingEscherichia coli in human urinary tract infection

Cited by 9 publications

References 2 publications

Characterization of Escherichia coli Isolates from Hospital Inpatients or Outpatients with Urinary Tract Infection

Characterization of Escherichia coli Isolates from Hospital Inpatients or Outpatients with Urinary Tract Infection

Characterization of Urinary Tract Infection-Associated Shiga Toxin-Producing Escherichia coli

Fimoperon variation in the emergence of EnterohemorrhagicEscherichia coli: an evolutionary and functional analysis

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