Association of Virulence Genotype with Phylogenetic Background in Comparison to Different Seropathotypes of Shiga Toxin-Producing Escherichia coli Isolates

Abstract

, stx 2-vha , and stx 2-vhb ) were concentrated in seropathotypes associated with disease, others (astA, HPI, stx 1c , and stx 2-NV206 ) were concentrated in seropathotypes that are not associated with disease. Taken together with the observation that the STEC-A group was exclusively composed of strains lacking eae recovered from seropathotypes that are not associated with disease, the "atypical" virulence pattern suggests that STEC-A strains comprise a distinct category of STEC strains. A practical benefit of our phylogenetic analysis of STEC strains is that phylogenetic group A status appears to be highly predictive of "nonvirulent" seropathotypes.

Genomic analysis of the PAI ICL3 locus in pathogenic LEE-negative Shiga toxin-producing Escherichia coli and Citrobacter rodentium

“…A striking phylogenetic distribution of the PAI I CL3 genotypes could explain this distinction. While six major phylogenetic groups of E. coli (A, B1, C, E, D and B2) form the core of the E. coli species (Escobar-Paramo et al, 2004), we showed in a previous study that LEE-negative STEC strains in seropathotype C belong exclusively to the ECOR group B1 (Girardeau et al, 2005). Therefore, the observed link between complete PAI I CL3 genotype and seropathotype C demonstrates a striking phylogenetic link between intact PAI I CL3 and ECOR group B1.…”

“…Recent studies have demonstrated that determination of the seropathotype distribution of virulence factors allows identification of DNA targets for selective detection of strains that present a risk to public health (Gilmour et al, 2006;Karmali et al, 2003). As we have shown, there is a link between seropathotype, prevalence of various virulence factors, phylogeny and Shiga toxin gene expression (de Sablet et al, 2008;Girardeau et al, 2005).…”

“…In a recent study we found a clear association of certain virulence factors with seropathotypes linked to disease (Girardeau et al, 2005). Consistent with these findings, this study showed a significantly higher prevalence of the PAI I CL3 in the virulent seropathotype C than in the non-virulent seropathotypes D and E. In addition, the presence of the PAI I CL3 element in most strains belonging to the virulent clonal group STEC-1 indicates that PAI I CL3 is a common component of the genome of certain E. coli lineages.…”

“…Although the LEE seems to confer enhanced virulence, LEE-negative STEC strains are also associated with severe human disease (Girardeau et al, 2005;Johnson et al, 1996;WHO, 1999). These observations suggest that other unknown factors, possibly GEIs or PAIs, enhance the virulence potential of STEC strains (Boerlin et al, 1999;Kaper et al, 1999;Karmali et al, 2003).…”

Shiga toxins and stx phages: highly diverse entities

“…A correlation has been observed between the stx 2 genotype and severity of disease, as several studies have shown that some stx 2 subtypes are frequently associated with a higher risk of developing HUS, whilst others are present mainly in strains isolated from patients with uncomplicated diarrhoea or in those not isolated from humans (Eklund, et al, 2002;Friedrich et al, 2002;Zhang et al, 2002;Jenkins et al, 2003;Leung et al, 2003;Beutin et al, 2004;Girardeau et al, 2005;Bielaszewska et al, 2006;Persson et al, 2007). By applying the recently proposed nomenclature to previous studies, it is possible to correlate stx 2a with high virulence and HUS, and stx 2e , stx 2f and stx 2g with low pathogenicity in humans.…”