title: Subtyping Escherichia coli Virulence Genes Isolated from Feces of Beef Cattle and Clinical Cases in Alberta.
abstract: Clinical outcomes of Shiga toxin (stx)-producing Escherichia coli infection are largely determined by virulence gene subtypes. This study used a polymerase chain reaction (PCR)-pyrosequencing assay to analyze single-nucleotide polymorphisms for subtyping three major virulence genes (stx1, stx2, eae) of pathogenic E. coli (O157, O26, O111, and O103) isolated from cattle over a 2-year interval (n = 465) and human clinical cases (n = 42) in western Canada. Most bovine isolates were PCR positive for at least one target virulence gene (367/465), whereas 100% of human isolates harbored eae in combination with at least one stx gene. Four Shiga toxin (1a, 2a, 2c, and 2e) and four eae (λ/γ1-eae, ɛ-eae, θ/γ2-eae, and β-eae) subtypes were identified in over 25 distinct virulence genotypes. Among cattle isolates, every serogroup, but O103, presented a dominant genotype (O157: stx1a+stx2a+λ/γ1-eae, O26: β-eae alone, and O111: stx1a+θ/γ2-eae). Similar patterns were found in human isolates, although it was not possible to establish a clear genotypic association between the two sources. Many O157 and non-O157 cattle isolates lacked stx genes; the absence was greater in non-O157 (75/258) and O157:non-H7 (19/40) than in O157:H7 strains (1/164). In addition, there was a greater diversity of virulence genotypes of E. coli isolated from cattle than those of human diseases, which could be due to sample characteristics (e.g., source and clinical condition). However, the majority of cattle strains had virulence profiles identical to those of clinical cases. Consequently, determining the presence of certain stx (stx1aand stx2a) and eae (λ/γ1-eae) subtypes known to cause human disease would be a valuable tool for risk assessment and prediction of disease outcome along the farm-to-fork continuum.
authors.affiliation: 1 Department of Microbiology, Immunology and Infectious Diseases, University of Calgary , Calgary, Canada .
authors.forename: Renata
authors.initials: R
authors.lastname: Tostes
authors.affiliation: 2 Lethbridge Laboratory, National Centres for Animal Disease, Canadian Food Inspection Agency , Lethbridge, Canada .
authors.forename: Noriko
authors.initials: N
authors.lastname: Goji
authors.affiliation: 2 Lethbridge Laboratory, National Centres for Animal Disease, Canadian Food Inspection Agency , Lethbridge, Canada .
authors.forename: Kingsley
authors.initials: K
authors.lastname: Amoako
authors.affiliation: 3 Alberta Provincial Laboratory for Public Health , Edmonton, Canada .
authors.forename: Linda
authors.initials: L
authors.lastname: Chui
authors.affiliation: 4 Faculty of Veterinary Medicine, Production Animal Health, University of Calgary, Calgary, Canada .
authors.forename: John
authors.initials: J
authors.lastname: Kastelic
authors.affiliation: 1 Department of Microbiology, Immunology and Infectious Diseases, University of Calgary , Calgary, Canada .
authors.forename: Rebekah
authors.initials: R
authors.lastname: DeVinney
authors.affiliation: 5 Alberta Agriculture and Forestry , Lethbridge, Canada .
authors.forename: Kim
authors.initials: K
authors.lastname: Stanford
authors.affiliation: 5 Alberta Agriculture and Forestry , Lethbridge, Canada .
authors.forename: Tim
authors.initials: T
authors.lastname: Reuter
mesh_terms: D000416:Alberta; D000818:Animals; D002238:Carbohydrate Epimerases / Q000235:genetics; D002417:Cattle / Q000382:microbiology; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology*; D005506:Food Contamination; D005516:Food Microbiology; D005798:Genes, Bacterial; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D000069466:Red Meat / Q000382:microbiology*; D012703:Serotyping; D022603:Shiga Toxins / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D000637:Transaminases / Q000235:genetics
chemical_list: D022603:Shiga Toxins; D000637:Transaminases; D002238:Carbohydrate Epimerases; C061272:perosamine synthetase
keywords: STEC; Shiga toxin; genotype; intimin; pyrosequencing; subtyping