title: Geographically distinct Escherichia coli O157 isolates differ by lineage, Shiga toxin genotype, and total shiga toxin production.
abstract: While the differential association of Escherichia coli O157 genotypes with animal and human hosts has recently been well documented, little is known about their distribution between countries and how this might affect regional disease rates. Here, we used a 48-plex single nucleotide polymorphism (SNP) assay to segregate 148 E. coli O157 isolates from Australia, Argentina, and the United States into 11 SNP lineages. We also investigated the relationship between SNP lineages, Shiga toxin (Stx) gene profiles, and total Stx production. E. coli O157 isolates clearly segregated into SNP lineages that were differentially associated with each country. Of the 11 SNP lineages, seven were detected among isolates from a single country, two were detected among isolates from all three countries, and another two were detected only among U.S. and Argentinean isolates. A number of Australian (30%) and Argentinean (14%) isolates were associated with novel, previously undescribed SNP lineages that were unique to each country. Isolates within SNP lineages that were strongly associated with the carriage of stx2a produced comparatively more Stx on average than did those lacking the stx2a subtype. Furthermore, the proportion of isolates in stx2a-associated SNP lineages was significantly higher in Argentina and the United States than Australia (P < 0.05). This study provides evidence for the geographic divergence of E. coli O157 and for a prominent role of stx2a in total Stx production. These results also highlight the need for more comprehensive studies of the global distribution of E. coli O157 lineages and the impacts of regionally predominant E. coli O157 lineages on the prevalence and severity of disease.
authors.affiliation: CSIRO Food and Nutrition Flagship, Archerfield, QLD, Australia glen.mellor@csiro.au.
authors.forename: Glen E
authors.initials: GE
authors.lastname: Mellor
authors.affiliation: CSIRO Food and Nutrition Flagship, Werribee, VIC, Australia.
authors.forename: Narelle
authors.initials: N
authors.lastname: Fegan
authors.affiliation: CSIRO Food and Nutrition Flagship, Werribee, VIC, Australia.
authors.forename: Kari S
authors.initials: KS
authors.lastname: Gobius
authors.affiliation: Forensic and Scientific Services, Department of Health, Archerfield, QLD, Australia.
authors.forename: Helen V
authors.initials: HV
authors.lastname: Smith
authors.affiliation: Forensic and Scientific Services, Department of Health, Archerfield, QLD, Australia.
authors.forename: Amy V
authors.initials: AV
authors.lastname: Jennison
authors.affiliation: Servicio Fisiopatogenia, Instituto Nacional de Enfermedades Infecciosas-ANLIS "Dr. Carlos G. Malbrán," Buenos Aires, Argentina.
authors.forename: Beatriz A
authors.initials: BA
authors.lastname: D'Astek
authors.affiliation: Servicio Fisiopatogenia, Instituto Nacional de Enfermedades Infecciosas-ANLIS "Dr. Carlos G. Malbrán," Buenos Aires, Argentina.
authors.forename: Marta
authors.initials: M
authors.lastname: Rivas
authors.affiliation: Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, Washington, USA.
authors.forename: Smriti
authors.initials: S
authors.lastname: Shringi
authors.affiliation: Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, Washington, USA.
authors.forename: Katherine N K
authors.initials: KN
authors.lastname: Baker
authors.affiliation: Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, Washington, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Besser
mesh_terms: D000818:Animals; D001118:Argentina / Q000453:epidemiology; D001315:Australia / Q000453:epidemiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary; D019453:Escherichia coli O157 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D058974:Phylogeography; D020641:Polymorphism, Single Nucleotide; D022621:Shiga Toxin / Q000235:genetics* / Q000378:metabolism; D014481:United States / Q000453:epidemiology
chemical_list: D022621:Shiga Toxin