Phylogenetic Backgrounds and Virulence Profiles of Atypical Enteropathogenic Escherichia coli Strains from a Case-Control Study Using Multilocus Sequence Typing and DNA Microarray Analysis

Abstract

Atypical enteropathogenetic Escherichia coli (EPEC) strains are frequently detected in children with diarrhea but are also a common finding in healthy children. The aim of this study was to compare the phylogenetic ancestry and virulence characteristics of atypical (eae positive, stx and bfpA negative) EPEC strains from Norwegian children with (n ‫؍‬ 37) or without (n ‫؍‬ 19) diarrhea and to search for an association between phylogenetic ancestry and diarrhea. The strains were classified in phylogenetic groups by phylogenetic marker genes and in sequence types (STs) by multilocus sequence typing. Phylogenetic ancestry was compared to virulence characteristics based on DNA microarray analysis. Serotyping and pulsed-field gel electrophoresis (PFGE) were also performed. All four phylogenetic groups, 26 different STs, and 20 different clonal groups were represented among the 56 atypical EPEC strains. The strains were separated into three clusters by overall virulence gene profile; one large cluster with A, B1, and D strains and two clusters with group B2 strains. There was considerable heterogeneity in the PFGE profiles and serotypes, and almost half of the strains were O nontypeable. The efa1/lifA gene, previously shown to be statistically linked with diarrhea in this strain collection (J. E. Afset et al., J. Clin. Microbiol. 44:3703-3711, 2006), was present in 8 of 26 STs. The two phylogenetic groups B1 and D were weakly associated with diarrhea (P ‫؍‬ 0.06 and P ‫؍‬ 0.09, respectively). In contrast, group B2 was isolated most frequently from healthy controls (P ‫؍‬ 0.05). In conclusion, the atypical EPEC strains were heterogeneous both phylogenetically and by virulence profile. Phylogenetic ancestry was less useful as a predictor of diarrhea than were specific virulence genes.

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

“…Whether O157 isolates with fliC types other than H7 and H16 can be rated as only low pathogenic is difficult to say from the data presented here since the numbers of isolates of these serotypes were quite low; it is clear, however, that they were very unlikely to have originated from formerly stx-positive O157 strains. Several other studies corroborate our findings since the vast majority of O157 isolates with fliCH34, -H39, and -H45 were isolated either from animals or food only or from humans without HUS (3,(39)(40)(41)(42)(43)(44)(45)(46). Recently, Sanjar et al performed a similar analysis, focusing on the phylogenomic classification of O157:non-H7 isolates (31).…”

Caracterização molecular de Escherichia coli enteropatogênica atípica em animais silvestres capturados na Região Amazônica

“…Estudos com aEPEC têm focado principalmente na comparação entre cepas isoladas de casos diarreicos e de pacientes saudáveis 24,25,26 . Mais recentemente, a identificação da presença de tipos de EPEC potencialmente patogênicos para humanos, isolados de animais, pode indicar que a transmissão desses microrganismos entre animais e seres humanos ocorre e tem um impacto sobre a saúde pública 6 ; porém pouco se tem avaliado acerca da ocorrência desses patógenos em animais silvestres.…”

“…Dessa forma, o presente estudo buscou a identificação das subclasses de intiminas em animais silvestres e observou a ocorrência das subclasses ζ, β1, β2 e ε, como aquelas que estão neles circulando. Como essas subclasses já foram descritas em seres humanos e animais de criação 6,24,25,26 , os dados podem apontar para uma possível contaminação da fauna silvestre por cepas provenientes da contaminação ambiental ou que esses espécimes estão servindo de reservatórios naturais para esse patógeno.…”

Phylogenetic and pathotype analysis of Escherichia coli swine isolates from Southern Brazil

“…coli isolates are characterized into different pathotypes according to the presence of speciϐic virulence factors. The main pathotypes in swine diseases are enterotoxigenic E. coli (ETEC), characterized by the presence of the toxins STa, STb and LT and F4,F5,F6,F18 or F41 ϐimbria;enteropathogenic E. coli (EPEC), which carries the eae gene; Shiga toxigenic or Verotoxigenic E. coli (STEC or VTEC), characterized by the presence of factors such as F18a/b ϐimbria and Stx2 toxin, and ϐinally uropathogenic E. coli (UPEC), which carries at least one of the following genes: cnf, hly, bfp, eae, sfa, pap, iha and usp (Brito et al 1999, Campos et al 2008, Afset et al 2008.…”