Occurrence of
 hlyA
 and
 sheA
 Genes in Extraintestinal
 Escherichia coli
 Strains

Kerényi, Mónika; Allison, Heather E.; Bátai, I.; Sonnevend, Ágnes; Emödy, Levente; Plaveczky, Nóra; Pál, Tibor

doi:10.1128/jcm.43.6.2965-2968.2005

Cited by 41 publications

(28 citation statements)

References 26 publications

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“…As described previously, we could confirm the presence of the EAEC marker genes astA and pic in other E. coli pathotypes (21). Since these strains harbor at least one other major virulence factor indicative of a particular pathotype, they have been grouped into the associated pathogroup.…”

Section: Resultssupporting

confidence: 75%

Identification of Unconventional Intestinal Pathogenic Escherichia coli Isolates Expressing Intermediate Virulence Factor Profiles by Using a Novel Single-Step Multiplex PCR

Müller

Greune

Heusipp

et al. 2007

Appl Environ Microbiol

200

159

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Intestinal pathogenic Escherichia coli represents a global health problem for mammals, including humans. At present, diarrheagenic E. coli bacteria are grouped into seven major pathotypes that differ in their virulence factor profiles, severity of clinical manifestations, and prognosis. In this study, we developed and evaluated a one-step multiplex PCR (MPCR) for the straightforward differential identification of intestinal pathotypes of E. coli. The specificity of this novel MPCR was validated by using a subset of reference strains and further confirmed by PCR-independent pheno-and genotypic characterization. Moreover, we tested 246 clinical E. coli isolates derived from diarrhea patients from several distinct geographic regions. Interestingly, besides strains belonging to the defined and well-described pathotypes, we identified five unconventional strains expressing intermediate virulence factor profiles. These strains have been further characterized and appear to represent intermediate strains carrying genes and expressing factors associated with enteropathogenic E. coli, Shiga toxin-producing E. coli, enterotoxigenic E. coli, and enteroaggregative E. coli alike. These strains represent further examples of the extraordinary plasticity of the E. coli genome. Moreover, this implies that the important identification of specific pathotypes has to be based on a broad matrix of indicator genes. In addition, the presence of intermediate strains needs to be accounted for.

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Section: Resultssupporting

confidence: 75%

Identification of Unconventional Intestinal Pathogenic Escherichia coli Isolates Expressing Intermediate Virulence Factor Profiles by Using a Novel Single-Step Multiplex PCR

Müller

Greune

Heusipp

et al. 2007

Appl Environ Microbiol

200

159

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“…Furthermore, derepression of the hly determinant, as well as the amount of secreted alpha-hemolysin, In addition to alpha-hemolysin, some enterobacteria express another type of pore-forming toxin, namely, ClyA (also known as SheA/HlyE), which could also contribute to the hemolytic phenotype (34), and clyA expression was found to be silenced by H-NS in nonpathogenic E. coli K-12 (14,47). However, in UPEC strain 536 as well as in most other uropathogenic isolates, a large portion (217 bp) of the clyA gene is deleted (21,24). Therefore, we assume that alpha-hemolysin is solely mediating the hyperhemolytic phenotype of the hns mutants.…”

Section: Discussionmentioning

confidence: 99%

Role of Histone-Like Proteins H-NS and StpA in Expression of Virulence Determinants of Uropathogenic Escherichia coli

et al. 2006

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The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli isolate by using DNA arrays. Expression profiling revealed that more than 500 genes were affected by an hns mutation, whereas no effect of StpA alone was observed. An hns stpA double mutant showed a distinct gene expression pattern that differed in large part from that of the hns single mutant. This suggests a direct interaction between the two paralogues and the existence of distinct regulons of H-NS and an H-NS/StpA heteromeric complex. hns mutation resulted in increased expression of alpha-hemolysin, fimbriae, and iron uptake systems as well as genes involved in stress adaptation. Furthermore, several other putative virulence genes were found to be part of the H-NS regulon. Although the lack of H-NS, either alone or in combination with StpA, has a huge impact on gene expression in pathogenic E. coli strains, its effect on virulence is ambiguous. At a high infection dose, hns mutants trigger more sudden lethality due to their increased acute toxicity in murine urinary tract infection and sepsis models. At a lower infectious dose, however, mutants lacking H-NS are attenuated through their impaired growth rate, which can only partially be compensated for by the higher expression of numerous virulence factors.Uropathogenic Escherichia coli (UPEC) is the leading cause of uncomplicated urinary tract infections, the most common bacterial infection in industrialized countries (28). The ability of these pathogenic variants to colonize the urinary tract is linked to the presence of virulence factors encoded by horizontally acquired genes not present in their nonpathogenic relatives. These factors include adhesins, cytotoxins, iron uptake systems, capsular polysaccharide, and serum resistance. In E. coli strain 536 (

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“…The eae, pEAF, bfp, and ehxA sequences were detected by colony hybridization assays with specific DNA probes, as previously described (40). The primers and conditions employed in the PCR assays for identification of gene sequences related to efa1 (23), iha (22), saa (42), lpfA O113 (21), toxB (24), paa (25), katP (43), espP (43), espI (44), lpf (45), astA (46), ldaH (27), sheA (47), espC (48), and hlyA (49) were reported previously.…”

Section: Methodsmentioning

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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Occurrence of hlyA and sheA Genes in Extraintestinal Escherichia coli Strains

Cited by 41 publications

References 26 publications

Identification of Unconventional Intestinal Pathogenic Escherichia coli Isolates Expressing Intermediate Virulence Factor Profiles by Using a Novel Single-Step Multiplex PCR

Identification of Unconventional Intestinal Pathogenic Escherichia coli Isolates Expressing Intermediate Virulence Factor Profiles by Using a Novel Single-Step Multiplex PCR

Role of Histone-Like Proteins H-NS and StpA in Expression of Virulence Determinants of Uropathogenic Escherichia coli

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

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