Association of virulence genotype with phylogenetic background in comparison to different seropathotypes of Shiga toxin-producing Escherichia coli isolates.
The distribution of virulent factors (VFs) in 287 Shiga toxin-producing Escherichia coli (STEC) strains that were classified according to Karmali et al. into five seropathotypes (M. A. Karmali, M. Mascarenhas, S. Shen, K. Ziebell, S. Johnson, R. Reid-Smith, J. Isaac-Renton, C. Clark, K. Rahn, and J. B. Kaper, J. Clin. Microbiol. 41:4930-4940, 2003) was investigated. The associations of VFs with phylogenetic background were assessed among the strains in comparison with the different seropathotypes. The phylogenetic analysis showed that STEC strains segregated mainly in phylogenetic group B1 (70%) and revealed the substantial prevalence (19%) of STEC belonging to phylogenetic group A (designated STEC-A). The presence of virulent clonal groups in seropathotypes that are associated with disease and their absence from seropathotypes that are not associated with disease support the concept of seropathotype classification. Although certain VFs (eae, stx(2-EDL933), 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.
Girardeau
Jean Pierre
JP
Institut National de Recherches Agronomiques, Laboratoire de Microbiologie, Centre de Recherche INRA de Clermont Ferrand Theix, 63122 Saint-Genès Champanelle, France. girard@clermont.inra.fr
Dalmasso
Alessandra
A
Bertin
Yolande
Y
Ducrot
Christian
C
Bord
Séverine
S
Livrelli
Valérie
V
Vernozy-Rozand
Christine
C
Martin
Christine
C
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D004783:Environmental Microbiology; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005516:Food Microbiology; D005838:Genotype; D006801:Humans; D010802:Phylogeny; D012703:Serotyping; D022603:Shiga Toxins / Q000096:biosynthesis*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
D029968:Escherichia coli Proteins; D022603:Shiga Toxins; D037521:Virulence Factors