title: Hospital and community ampicillin-resistant Enterococcus faecium are evolutionarily closely linked but have diversified through niche adaptation.
abstract: BACKGROUND
  Ampicillin-resistant Enterococcus faecium (ARE) has emerged as a nosocomial pathogen. Here, we quantified ARE carriage in different community sources and determined genetic relatedness with hospital ARE.
  
  
  RESULTS
  ARE was recovered from rectal swabs of 24 of 79 (30%) dogs, 11 of 85 (13%) cats and 0 of 42 horses and from 3 of 40 (8%) faecal samples of non-hospitalized humans receiving amoxicillin. Multi-locus Sequence Typing revealed 21 sequence types (STs), including 5 STs frequently associated with hospital-acquired infections. Genes previously found to be enriched in hospital ARE, such as IS16, orf903, orf905, orf907, were highly prevalent in community ARE (≥79%), while genes with a proposed role in pathogenesis, such as esp, hyl and ecbA, were found rarely (≤5%) in community isolates. Comparative genome analysis of 2 representative dog isolates revealed that the dog strain of ST192 was evolutionarily closely linked to two previously sequenced hospital ARE, but had, based on gene content, more genes in common with the other, evolutionarily more distantly related, dog strain (ST266).
  
  
  CONCLUSIONS
  ARE were detected in dogs, cats and sporadically in healthy humans, with evolutionary linkage to hospital ARE. Yet, their accessory genome has diversified, probably as a result of niche adaptation.
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands. mjaderegt@gmail.com
authors.forename: Marieke J A
authors.initials: MJ
authors.lastname: de Regt
authors.forename: Willem
authors.initials: W
authors.lastname: van Schaik
authors.forename: Miranda
authors.initials: M
authors.lastname: van Luit-Asbroek
authors.forename: Huberta A T
authors.initials: HA
authors.lastname: Dekker
authors.forename: Engeline
authors.initials: E
authors.lastname: van Duijkeren
authors.forename: Catherina J M
authors.initials: CJ
authors.lastname: Koning
authors.forename: Marc J M
authors.initials: MJ
authors.lastname: Bonten
authors.forename: Rob J L
authors.initials: RJ
authors.lastname: Willems
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D000667:Ampicillin / Q000494:pharmacology*; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D005075:Biological Evolution; D002415:Cats; D004285:Dogs; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation / Q000187:drug effects; D006736:Horses; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D012111:Residence Characteristics; D014774:Virulence / Q000187:drug effects / Q000235:genetics
chemical_list: D000890:Anti-Infective Agents; D000667:Ampicillin