title: Potentially human-pathogenic Escherichia coli O26 in Norwegian sheep flocks.
abstract: A national survey of Escherichia coli O26 in Norwegian sheep flocks was conducted, using fecal samples to determine the prevalence. In total, 491 flocks were tested, and E. coli O26 was detected in 17.9% of the flocks. One hundred forty-two E. coli O26 isolates were examined for flagellar antigens (H typing) and four virulence genes, including stx and eae, to identify possible Shiga toxin-producing E. coli (STEC) and enteropathogenic E. coli (EPEC). Most isolates (129 out of 142) were identified as E. coli O26:H11. They possessed eae and may have potential as human pathogens, although only a small fraction were identified as STEC O26:H11, giving a prevalence in sheep flocks of only 0.8%. Correspondingly, the sheep flock prevalence of atypical EPEC (aEPEC) O26:H11 was surprisingly high (15.9%). The genetic relationship between the E. coli O26:H11 isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA), identifying 63 distinct PFGE profiles and 22 MLVA profiles. Although the MLVA protocol was less discriminatory than PFGE and a few cases of disagreement were observed, comparison by partition mapping showed an overall good accordance between the two methods. A close relationship between a few isolates of aEPEC O26:H11 and STEC O26:H11 was identified, but all the E. coli O26:H11 isolates should be considered potentially pathogenic to humans. The present study consisted of a representative sampling of sheep flocks from all parts of Norway. This is the first large survey of sheep flocks focusing on E. coli O26 in general, including results of STEC, aEPEC, and nonpathogenic isolates.
authors.affiliation: Norwegian Veterinary Institute, Oslo, Norway.
authors.forename: C
authors.initials: C
authors.lastname: Sekse
authors.forename: M
authors.initials: M
authors.lastname: Sunde
authors.forename: B-A
authors.initials: BA
authors.lastname: Lindstedt
authors.forename: P
authors.initials: P
authors.lastname: Hopp
authors.forename: T
authors.initials: T
authors.lastname: Bruheim
authors.forename: K S
authors.initials: KS
authors.lastname: Cudjoe
authors.forename: B
authors.initials: B
authors.lastname: Kvitle
authors.forename: A M
authors.initials: AM
authors.lastname: Urdahl
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis* / Q000276:immunology; D015373:Bacterial Typing Techniques; D016521:Electrophoresis, Gel, Pulsed-Field; D054308:Enteropathogenic Escherichia coli / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000662:veterinary*; D029968:Escherichia coli Proteins; D005243:Feces / Q000382:microbiology; D058885:Multilocus Sequence Typing; D009664:Norway / Q000453:epidemiology; D019081:O Antigens / Q000032:analysis* / Q000276:immunology; D012703:Serotyping; D012756:Sheep / Q000382:microbiology*; D012757:Sheep Diseases / Q000453:epidemiology*; D022621:Shiga Toxin / Q000096:biosynthesis; D037521:Virulence Factors
chemical_list: D000942:Antigens, Bacterial; D029968:Escherichia coli Proteins; C022863:H antigen; D019081:O Antigens; D037521:Virulence Factors; D022621:Shiga Toxin