title: Genetic relatedness of commensal Escherichia coli from nursery pigs in intensive pig production in Denmark and molecular characterization of genetically different strains.
abstract: OBJECTIVE
  To determine the genetic relatedness and the presence of virulence and antibiotic resistance genes in commensal Escherichia coli from nursery pigs in Danish intensive production.
  
  
  RESULTS
  The genetic diversity of 1000 E. coli strains randomly picked (N = 50 isolates) from cultured faecal samples (N = 4 pigs) from five intensive Danish pigs farms was analysed by repetitive extragenic palindromic-PCR (REP-PCR) and 42 unique REP-profiles were detected (similarity <92%). One profile was dominant (67.2% of strains) but farms differed significantly in the diversity of commensal E. coli: between eight and 21 different profiles per farm were detected. One to three strains representing each REP-profile were characterized by multilocus typing scheme-typing, as well as for presence of antimicrobial and virulence genes and serogrouping through microarray analysis. The 42 REP-profiles were classified into 22 different sequence types (ST) with ST10 being the most common, encompassing 10 REP-profiles. Resistance and virulence genes were detected in most of the isolates. Genes encoding AmpC-β-lactamases and quinolone resistance were found in one and three isolates, respectively. Toxin-producing genes were observed in 20 isolates.
  
  
  CONCLUSIONS
  A low genetic diversity was found in commensal gut E. coli from nursery pigs in Denmark. No correlation was observed between REP-profiles, ST-types and resistance/virulence patterns.
  
  
  CONCLUSIONS
  This is the first study analysing in depth the genetic variability of commensal E. coli from pigs in Danish intensive pig production. A tendency for higher diversity was observed with in nursery pigs that were treated with zinc oxide only, in absence of other antimicrobials. Strains with potential to disseminate virulence and antibiotic resistance genes to pathogenic subgroups of E. coli were found to be wide-spread.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Herrero-Fresno
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: I
authors.initials: I
authors.lastname: Larsen
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: J E
authors.initials: JE
authors.lastname: Olsen
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003718:Denmark; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D005243:Feces / Q000382:microbiology; D005260:Female; D014644:Genetic Variation; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D034421:Sus scrofa / Q000254:growth & development / Q000382:microbiology*; D013552:Swine; D013559:Symbiosis; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: E. coli; MLST-typing; REP-PCR; antimicrobial resistance; genetic relatedness; microarrays; serogrouping; virulence