Atypical enteropathogenic<i>Escherichia coli</i>genomic background allows the acquisition of non-EPEC virulence factors

Bando, Sílvia Yumi; Andrade, Fernanda B.; Guth, Beatriz E. C.; Elias, Waldir P.; Moreira-Filho, Carlos Alberto; Castro, AntÃ´nio Fernando Pestana de

doi:10.1111/j.1574-6968.2009.01735.x

Cited by 29 publications

(37 citation statements)

References 38 publications

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“…All of the other eae-positive E. coli O157 strains with fliCH16, -H34, -H39, or -H45 are distinct from the O157:H7 complex; these clones are also distinct from each other. This finding is in agreement with the genetic diversity reported for other atypical EPEC strains (14,35). In our previous study, we showed that atypical EPEC strains consist, in general, of two major groups (12,14).…”

Section: Discussionsupporting

confidence: 82%

Molecular Characterization of Human Atypical Sorbitol-Fermenting Enteropathogenic Escherichia coli O157 Reveals High Diversity

Kossow¹,

Zhang²,

Bielaszewska³

et al. 2016

J Clin Microbiol

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Alongside the well-characterized enterohemorrhagic Escherichia coli (EHEC) O157:H7, serogroup O157 comprises sorbitolfermenting typical and atypical enteropathogenic E. coli (EPEC/aEPEC) strains that carry the intimin-encoding gene eae but not Shiga toxin-encoding genes (stx). Since little is known about these pathogens, we characterized 30 clinical isolates from patients with hemolytic uremic syndrome (HUS) or uncomplicated diarrhea with respect to their flagellin gene (fliC) type and multilocus sequence type (MLST). Moreover, we applied whole-genome sequencing (WGS) to determine the phylogenetic relationship with other eae-positive EHEC serotypes and the composition of the rfbO157 region. fliC typing resulted in five fliC types (H7, H16, H34, H39, and H45). Isolates of each fliC type shared a unique ST. In comparison to the 42 HUS-associated E. coli (HUSEC) strains, only the stx-negative isolates with fliCH7 shared their ST with EHEC O157:H7/H ؊ strains. With the exception of one O157:H ؊ fliCH16 isolate, HUS was exclusively associated with fliCH7. WGS corroborated the separation of the fliCH7 isolates, which were closely related to the EHEC O157:H7/H ؊ isolates, and the diverse group of isolates exhibiting different fliC types, indicating independent evolution of the different serotypes. This was also supported by the heterogeneity within the rfbO157 region that exhibited extensive recombinations. The genotypic subtypes and distribution of clinical symptoms suggested that the stx-negative O157 strains with fliCH7 were originally EHEC strains that lost stx. The remaining isolates form a distinct and diverse group of atypical EPEC isolates that do not possess the full spectrum of virulence genes, underlining the importance of identifying the H antigen for clinical risk assessment.

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Section: Discussionsupporting

confidence: 82%

Molecular Characterization of Human Atypical Sorbitol-Fermenting Enteropathogenic Escherichia coli O157 Reveals High Diversity

Kossow¹,

Zhang²,

Bielaszewska³

et al. 2016

J Clin Microbiol

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“…The detection of these genes, particularly in the aEPEC subgroup, is in accordance with a study showing that aEPEC strains belonging to particular phylogenetic clusters have genetic similarity to enterohemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), diffusely adherent E. coli (DAEC), or enteroaggregative E. coli (EAEC) (8).…”

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confidence: 50%

“…Indeed, phylogenetic studies have indicated that aEPEC strains have a genomic background with characteristics that allow the acquisition, retention, and expression of genes encoding virulence factors of other DEC pathotypes (7,8).…”

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confidence: 99%

Autotransporter Protein-Encoding Genes of Diarrheagenic Escherichia coli Are Found in both Typical and Atypical Enteropathogenic E. coli Strains

Abreu

Bueris

Porangaba

et al. 2013

Appl Environ Microbiol

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c Autotransporter (AT) protein-encoding genes of diarrheagenic Escherichia coli (DEC) pathotypes (cah, eatA, ehaABCDJ, espC, espI, espP, pet, pic, sat, and tibA) were detected in typical and atypical enteropathogenic E. coli (EPEC) in frequencies between 0.8% and 39.3%. Although these ATs have been described in particular DEC pathotypes, their presence in EPEC indicates that they should not be considered specific virulence markers.

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“…On the other hand, except for one isolate, all stx-negative EHEC derivative and aEPEC isolates carrying several of the virulence factors studied belonged to the B1 group, and most were isolated from diarrheic children. The classification of O26 aEPEC and EHEC isolates into the B1 group has also been described by others (62,63).…”

Section: Discussionmentioning

confidence: 99%

Molecular and Phenotypic Characterization of Escherichia coli O26:H8 among Diarrheagenic E. coli O26 Strains Isolated in Brazil

Piazza¹,

Delannoy²,

Fach³

et al. 2013

Appl Environ Microbiol

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f Escherichia coli strains of serogroup O26 comprise two distinct groups of pathogens, characterized as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC). Among the several genes related to type III secretion system-secreted effector proteins, espK was found to be highly specific for EHEC O26:H11 and its stx-negative derivative strains isolated in European countries. E. coli O26 strains isolated in Brazil from infant diarrhea, foods, and the environment have consistently been shown to lack stx genes and are thus considered atypical EPEC. However, no further information related to their genetic background is known. Therefore, in this study, we aimed to discriminate and characterize these Brazilian O26 stx-negative strains by phenotypic, genetic, and biochemical approaches. Among 44 isolates confirmed to be O26 isolates, most displayed flagellar antigen H11 or H32. Out of the 13 nonmotile isolates, 2 tested positive for fliC H11 , and 11 were fliC H8 positive. The identification of genetic markers showed that several O26:H11 and all O26:H8 strains tested positive for espK and could therefore be discriminated as EHEC derivatives. The presence of H8 among EHEC O26 and its stx-negative derivative isolates is described for the first time. The interaction of three isolates with polarized Caco-2 cells and with intestinal biopsy specimen fragments ex vivo confirmed the ability of the O26 strains analyzed to cause attaching-and-effacing (A/E) lesions. The O26:H32 strains, isolated mostly from meat, were considered nonvirulent. Knowledge of the virulence content of stx-negative O26 isolates within the same serotype helped to avoid misclassification of isolates, which certainly has important implications for public health surveillance.

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Atypical enteropathogenicEscherichia coligenomic background allows the acquisition of non-EPEC virulence factors

Cited by 29 publications

References 38 publications

Molecular Characterization of Human Atypical Sorbitol-Fermenting Enteropathogenic Escherichia coli O157 Reveals High Diversity

Molecular Characterization of Human Atypical Sorbitol-Fermenting Enteropathogenic Escherichia coli O157 Reveals High Diversity

Autotransporter Protein-Encoding Genes of Diarrheagenic Escherichia coli Are Found in both Typical and Atypical Enteropathogenic E. coli Strains

Molecular and Phenotypic Characterization of Escherichia coli O26:H8 among Diarrheagenic E. coli O26 Strains Isolated in Brazil

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