Occurrence of potentially human-pathogenic Escherichia coli O103 in Norwegian sheep.
The investigation of an outbreak of hemorrhagic-uremic syndrome in Norway in 2006 indicated that the outbreak strain Escherichia coli O103:H25 could originate from sheep. A national survey of the Norwegian sheep population was performed, with the aim of identifying and describing a possible reservoir of potentially human-pathogenic E. coli O103, in particular of the H types 2 and 25. The investigation of fecal samples from 585 sheep flocks resulted in 1,222 E. coli O103 isolates that were analyzed for the presence of eae and stx genes, while a subset of 369 isolates was further examined for flagellar antigens (H typing), stx subtypes, bfpA, astA, and molecular typing by pulsed-field gel electrophoresis (PFGE). The total ovine E. coli O103 serogroup was genetically diverse by numbers of H types, virulotypes, and PFGE banding patterns identified, although a tendency of clustering toward serotypes was seen. The flocks positive for potentially human-pathogenic E. coli O103 were geographically widely distributed, and no association could be found with county or geographical region. The survey showed that eae-negative, stx-negative E. coli O103, probably nonpathogenic to humans, is very common in sheep, with 27.5% of flocks positive. Moreover, the study documented a low prevalence (0.7%) of potentially human-pathogenic Shiga toxin-producing E. coli O103:H2, while STEC O103:H25 was not detected. However, 3.1% and 5.8% of the flocks were positive for enteropathogenic E. coli O103 belonging to H types 2 and 25, respectively. These isolates are of concern as potential human pathogens by themselves but more importantly as possible precursors for human-pathogenic STEC.
Norwegian Veterinary Institute, Oslo, Norway.
Camilla
C
Sekse
Marianne
M
Sunde
Petter
P
Hopp
Torkjel
T
Bruheim
Kofitsyo Sewornu
KS
Cudjoe
Bjørg
B
Kvitle
Anne Margrete
AM
Urdahl
D018829:Adhesins, Bacterial / Q000235:genetics; D000818:Animals; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D029968:Escherichia coli Proteins / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D005408:Flagellin / Q000235:genetics; D014644:Genetic Variation; D017720:Molecular Epidemiology; D058889:Molecular Typing; D009664:Norway; D012703:Serotyping; D012756:Sheep / Q000382:microbiology*; D022621:Shiga Toxin / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D037521:Virulence Factors; D005408:Flagellin; C073819:eaeA protein, E coli; D022621:Shiga Toxin