title: Persistence of vancomycin resistance in multiple clones of Enterococcus faecium isolated from Danish broilers 15 years after the ban of avoparcin.
abstract: The occurrence and diversity of vancomycin-resistant Enterococcus faecium (VREF) were investigated in 100 Danish broiler flocks 15 years after the avoparcin ban. VREF occurred in 47 flocks at low fecal concentrations detectable only by selective enrichment. Vancomycin resistance was prevalently associated with a transferable nontypeable plasmid lineage occurring in multiple E. faecium clones. Coselection of sequence type 842 by tetracycline use only partly explained the persistence of vancomycin resistance in the absence of detectable plasmid coresistance and toxin-antitoxin systems.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark vbo@sund.ku.dk.
authors.forename: Valeria
authors.initials: V
authors.lastname: Bortolaia
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Manuela
authors.initials: M
authors.lastname: Mander
authors.affiliation: Division of Food Microbiology, National Food Institute, Technical University of Denmark, Lyngby, Denmark.
authors.forename: Lars B
authors.initials: LB
authors.lastname: Jensen
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: John E
authors.initials: JE
authors.lastname: Olsen
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Luca
authors.initials: L
authors.lastname: Guardabassi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002645:Chickens / Q000382:microbiology; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics; D006020:Glycopeptides / Q000494:pharmacology*; D010957:Plasmids / Q000235:genetics; D020713:Vancomycin Resistance / Q000235:genetics / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides; C016249:avoparcin