title: The diversity of Listeria monocytogenes strains from 10 Icelandic sheep farms.
abstract: OBJECTIVE
  The purpose of this study was to examine the diversity of Listeria monocytogenes strains from healthy sheep, winter feed and environment of sheep farms in Iceland.
  
  
  RESULTS
  A total of 104 L. monocytogenes isolates from animals, winter feed and environment on 10 Icelandic sheep farms were compared by serotyping, ribotyping, and pulsed-field gel electrophoresis with ApaI and AscI. The isolates were divided into 24 genotypes, all identified as serovars 1/2a, 1/2b, or 4b. Nine genotypes were detected on more than one farm. On three of the farms there seemed to be a dominant strain of L. monocytogenes. Isolates from incidents of listeriosis in animals occurring on two of the farms belonged to the genotype most commonly found on the particular farm. Nine of the 24 genotypes found on the sheep farms have been associated with disease in animals and/or humans elsewhere in Iceland.
  
  
  CONCLUSIONS
  Certain strains of L. monocytogenes seem to be widely distributed on Icelandic sheep farms. On some farms there appears to be a dominant strain of L. monocytogenes. Incidents of listeriosis in animals may tend to be associated with strains commonly found on the farm.
  
  
  CONCLUSIONS
  This study demonstrates the diversity of L. monocytogenes present in healthy sheep and their environment.
authors.affiliation: Institute for Experimental Pathology, University of Iceland, Reykjavik, Iceland. kristigu@hi.is
authors.forename: K B
authors.initials: KB
authors.lastname: Gudmundsdottir
authors.forename: B
authors.initials: B
authors.lastname: Aalbaek
authors.forename: S
authors.initials: S
authors.lastname: Sigurdarson
authors.forename: E
authors.initials: E
authors.lastname: Gunnarsson
mesh_terms: D000821:Animal Feed / Q000382:microbiology*; D000818:Animals; D044822:Biodiversity; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D004777:Environment; D005243:Feces / Q000382:microbiology; D005838:Genotype; D007055:Iceland; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D008088:Listeriosis / Q000175:diagnosis / Q000662:veterinary*; D021521:Ribotyping / Q000379:methods; D012703:Serotyping / Q000379:methods; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology*