title: Escherichia coli O157:H7 lineages in healthy beef and dairy cattle and clinical human cases in Alberta, Canada.
abstract: The aim of this study was to examine the prevalence and distribution of Escherichia coli O157:H7 lineage-specific polymorphism assay (LSPA) 6 genotypes from cattle (n = 313) and clinical human (n = 203) isolates from northern and southern Alberta, Canada, to understand possible associations of genotypes with host and geographic location. The majority of cattle isolates (feedlot and dairy) typed as LSPA-6 111111 (72.2%), with proportionately higher LSPA-6 222222 (19.4%) than other LSPA-6 genotypes (10.7%). Clinical human isolates also typed primarily as LSPA-6 111111 (90.1%), but a higher percentage of genotypes (6.8%) other than LSPA-6 222222 (3.1%) was observed. A significantly higher frequency of LSPA-6 111111 in southern Alberta cattle (P < 0.0001) and a significant difference in LSPA-6 genotypes between human versus feedlot cattle from northern Alberta (P < 0.0001) were detected. LSPA-6 211111 genotype was third and second most common in cattle and humans, respectively, and several new LSPA-6 genotypes (n = 19) were also discovered. Despite avoiding over-representation of isolates from specific farms or outbreaks, higher strain diversity among cattle by pulsed-field gel electrophoresis (PFGE; 50 genotypes) in contrast to human (9 PFGE genotypes) isolates was observed. The majority of cattle (74.4%) and human (90.6%) isolates were susceptible to the antimicrobials tested. Within resistant cattle isolates, sulfisoxazole-tetracycline resistance was common (62.5%) and was accounted for by the presence of sul1 and sul2, and tet(A) and tet(B) determinants. An association between LSPA-6 and PFGE genotypes but not between geographic location and PFGE genotype for both hosts was evident.
authors.affiliation: Agriculture and Agri-Food Research Centre, P.O. Box 3000, Lethbridge, Alberta, Canada T1J 4B1. sharmar@agr.gc.ca
authors.forename: Ranjana
authors.initials: R
authors.lastname: Sharma
authors.forename: Kim
authors.initials: K
authors.lastname: Stanford
authors.forename: Marie
authors.initials: M
authors.lastname: Louie
authors.forename: Krysty
authors.initials: K
authors.lastname: Munns
authors.forename: S Jacob
authors.initials: SJ
authors.lastname: John
authors.forename: Yongxiang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Victor
authors.initials: V
authors.lastname: Gannon
authors.forename: Linda
authors.initials: L
authors.lastname: Chui
authors.forename: Ron
authors.initials: R
authors.lastname: Read
authors.forename: Edward
authors.initials: E
authors.lastname: Topp
authors.forename: Tim
authors.initials: T
authors.lastname: McAllister