title: Genotypic characterization and prevalence of virulence factors among Canadian Escherichia coli O157:H7 strains.
abstract: In this study, the association between genotypic and selected phenotypic characteristics was examined in a collection of Canadian Escherichia coli O157:H7 strains isolated from humans and cattle in the provinces of Alberta, Ontario, Saskatchewan, and Quebec. In a subset of 69 strains selected on the basis of specific phage types (PTs), a strong correlation between the lineage-specific polymorphism assay (LSPA6) genotype and PT was observed with all strains of PTs 4, 14, 21, 31, 33, and 87 belonging to the LSPA6 lineage I (LSPA6-LI) genotype, while those of PTs 23, 45, 67, and 74 belonged to LSPA6 lineage II (LSPA6-LII) genotypes. This correlation was maintained when additional strains of each PT were tested. E. coli O157:H7 strains with the LSPA6-LI genotype were much more common in the collection than were the LSPA6-LII or lineage I/II (LSPA6-LI/II)-related genotypes (82.6, 11.2, and 5.8%, respectively). Of the strains tested, proportionately more LSPA6-LI than LSPA6-LII genotype strains were isolated from humans (52.7% versus 19.7%) than from cattle (47.8% versus 80.2%). In addition, 96.7% of the LSPA6-LII strains carried the stx(2c) variant gene, while only 50.0% of LSPA6-LI/II and 2.7% of LSPA6-LI strains carried this gene. LSPA6-LII strains were also significantly more likely to possess the colicin D gene, cda (50.8% versus 23.2%), and have combined resistance to streptomycin, sulfisoxazole, and tetracycline (72.1% versus 0.9%) than were LSPA6-LI strains. The LSPA6 genotype- and PT-related characteristics identified may be important markers of specific ecotypes of E. coli O157:H7 that have unique epidemiological and virulence characteristics.
authors.affiliation: Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, Guelph, Ontario N1G 3W4, Canada.
authors.forename: Kim
authors.initials: K
authors.lastname: Ziebell
authors.forename: Marina
authors.initials: M
authors.lastname: Steele
authors.forename: Yongxiang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Andrew
authors.initials: A
authors.lastname: Benson
authors.forename: Eduardo N
authors.initials: EN
authors.lastname: Taboada
authors.forename: Chad
authors.initials: C
authors.lastname: Laing
authors.forename: Scott
authors.initials: S
authors.lastname: McEwen
authors.forename: Bruce
authors.initials: B
authors.lastname: Ciebin
authors.forename: Roger
authors.initials: R
authors.lastname: Johnson
authors.forename: Victor
authors.initials: V
authors.lastname: Gannon
mesh_terms: D000818:Animals; D001434:Bacteriophage Typing; D002170:Canada / Q000453:epidemiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D003087:Colicins / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D019453:Escherichia coli O157 / Q000145:classification* / Q000235:genetics; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D010641:Phenotype; D010957:Plasmids; D011110:Polymorphism, Genetic; D022641:Shiga Toxin 2 / Q000235:genetics; D037521:Virulence Factors / Q000145:classification* / Q000235:genetics
chemical_list: D003087:Colicins; D022641:Shiga Toxin 2; D037521:Virulence Factors