title: Characterization of European Yersinia enterocolitica 1A strains using restriction fragment length polymorphism and multilocus sequence analysis.
abstract: Yersinia enterocolitica is currently divided into two subspecies: subsp. enterocolitica including highly pathogenic strains of biotype 1B and subsp. palearctica including nonpathogenic strains of biotype 1A and moderately pathogenic strains of biotypes 2-5. In this work, we characterized 162 Y. enterocolitica strains of biotype 1A and 50 strains of biotypes 2-4 isolated from human, animal and food samples by restriction fragment length polymorphism using the HindIII restriction enzyme. Phylogenetic relatedness of 20 representative Y. enterocolitica strains including 15 biotype 1A strains was further studied by the multilocus sequence analysis of four housekeeping genes (glnA, gyrB, recA and HSP60). In all the analyses, biotype 1A strains formed a separate genomic group, which differed from Y. enterocolitica subsp. enterocolitica and from the strains of biotypes 2-4 of Y. enterocolitica subsp. palearctica. Based on these results, biotype 1A strains considered nonpathogenic should not be included in subspecies palearctica containing pathogenic strains of biotypes 2-5.
  
  
  CONCLUSIONS
  Yersinia enterocolitica strains are currently divided into six biotypes and two subspecies. Strains of biotype 1A, which are phenotypically and genotypically very heterogeneous, are classified as subspecies palearctica. In this study, European Y. enterocolitica 1A strains isolated from both human and nonhuman sources were characterized using restriction fragment length polymorphism and multilocus sequence analysis. The European biotype 1A strains formed a separate group, which differed from strains belonging to subspecies enterocolitica and palearctica. This may indicate that the current division between the two subspecies is not sufficient considering the strain diversity within Y. enterocolitica.
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland. anna.murros@helsinki.fi.
authors.forename: A
authors.initials: A
authors.lastname: Murros
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: E
authors.initials: E
authors.lastname: Säde
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Johansson
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Korkeala
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Fredriksson-Ahomaa
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Björkroth
mesh_terms: D000818:Animals; D018834:Chaperonin 60 / Q000235:genetics; D027081:DNA Gyrase / Q000235:genetics; D005516:Food Microbiology; D005838:Genotype; D005974:Glutamate-Ammonia Ligase / Q000235:genetics; D006801:Humans; D058885:Multilocus Sequence Typing / Q000379:methods*; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length / Q000235:genetics*; D011938:Rec A Recombinases / Q000235:genetics; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000378:metabolism; D015009:Yersinia Infections / Q000382:microbiology; D015008:Yersinia enterocolitica / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D018834:Chaperonin 60; C090528:DNA modification methylase HindIII; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D011938:Rec A Recombinases; D027081:DNA Gyrase; C081173:glutamine synthetase I; D005974:Glutamate-Ammonia Ligase
keywords: Yersinia enterocolitica; biotype 1A; multilocus sequence analysis; restriction fragment length polymorphism; subspecies enterocolitica; subspecies palearctica