Phylogenetic relationships of Shiga toxin-producing Escherichia coli isolated from Peruvian children

Aim: To determine the occurrence and characteristics of Shiga toxinproducing Escherichia coli (STEC) in drinking water supplies treated and untreated. Methods and Results: Drinking water samples (n = 1850) were collected from 41 municipalities in the north of Paran a State between February 2005 and January 2006. Escherichia coli isolates (n = 300) were recovered from water and investigated for the presence of virulence markers related to STEC by PCR. STEC isolates recovered were then characterized for both phenotypic and genotypic traits. A total of 12 isolates (11 from untreated water and one from treated water) were positive for stx, including five positive for both stx1 and stx2, two positive for stx1 and five positive for stx2. None of the STEC isolates contained eae, but other virulence genes were observed such as ehxA (100%), saa (100%), lpfA O113 (75%), iha (42%), subAB (25%) and cdtV (8%). Multidrug resistance was identified in 25% of the STEC isolates. The 12 STEC isolates belonged to seven distinct serotypes and pulsed-field gel electrophoresis typing revealed the presence of two clusters and two clones in this region. Conclusion: Drinking water, especially from untreated water supplies, can be source of STEC strains potentially pathogenic for humans. Significance and Impact of the Study: The investigation of the drinking water supplies for pathogenic E. coli, as STEC, may be useful to prevent waterborne outbreaks.

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“…; Contreras et al . ). In contrast, 50% of the STEC isolates of this study segregated mainly in B2 group.…”

Section: Discussionmentioning

confidence: 97%

Shiga toxin-producing Escherichia coli in drinking water supplies of north Paraná State, Brazil

et al. 2013

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“…Particularly, with respect to the two O26:H11 isolates, they did not cluster together (one of them was a singleton) and none were assigned to ST106, a ST commonly associated with this serotype (Ziebell et al, 2008; Abu-Ali et al, 2009; Contreras et al, 2011). Genetic diversity of O26:H11 has also been demonstrated in previous studies analyzing different genomic regions (Zhang et al, 2000; Bonanno et al, 2015; Krüger et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Genetic Relatedness and Novel Sequence Types of Non-O157 Shiga Toxin-Producing Escherichia coli Strains Isolated in Argentina

Cadona

Bustamante

González

et al. 2016

Front. Cell. Infect. Microbiol.

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Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen responsible for severe disease in humans such as hemolytic uremic syndrome (HUS) and cattle, the principal reservoir. Identification of the clones/lineages is important as several characteristics, among them propensity to cause disease varies with STEC phylogenetic origin. At present, we do not know what STEC clones, especially of non-O157:H7, are circulating in Argentina. To fill this knowledge gap we assessed the genetic diversity of STEC strains isolated in Argentina from various sources, mostly cattle and food, using multilocus sequence typing (MLST). Our objectives were to determine the phylogenetic relationships among strains and to compare them with strains from different geographic origins, especially with those from clinical human cases, in order to evaluate their potential health risk. A total of 59 STEC isolates from 41 serotypes were characterized by MLST. Analysis using EcMLST database identified 38 sequence types (ST), 17 (45%) of which were new STs detected in 18 serotypes. Fifteen out of 38 STs identified were grouped into 11 clonal groups (CGs) and, 23 not grouped in any of the defined CGs. Different STs were found in the same serotype. Results highlighted a high degree of phylogenetic heterogeneity among Argentinean strains and they showed that several cattle and food isolates belonged to the same STs that are commonly associated with clinical human cases in several geographical areas. STEC is a significant public health concern. Argentina has the highest incidence of HUS in the world and this study provides the first data about which STEC clones are circulating. Data showed that most of them might pose a serious zoonotic risk and this information is important for developing public health initiatives. However, the actual potential risk will be defined by the virulence profiles, which may differ among isolates belonging to the same ST.

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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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Phylogenetic relationships of Shiga toxin-producing Escherichia coli isolated from Peruvian children

Cited by 19 publications

References 32 publications

Shiga toxin-producing Escherichia coli in drinking water supplies of north Paraná State, Brazil

Shiga toxin-producing Escherichia coli in drinking water supplies of north Paraná State, Brazil

Genetic Relatedness and Novel Sequence Types of Non-O157 Shiga Toxin-Producing Escherichia coli Strains Isolated in Argentina

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

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