title: Complete nucleotide sequence of pVQS1 containing a quinolone resistance determinant from Salmonella enterica serovar Virchow associated with foreign travel.
abstract: OBJECTIVE
  Nalidixic acid-resistant Salmonella enterica serovars Kentucky (n = 5) and Virchow (n = 6) cultured from individuals were investigated for the presence of plasmid-mediated quinolone resistance (PMQR) determinants.
  
  
  METHODS
  PMQR markers and mutations within the quinolone resistance-determining regions of the target genes were investigated by PCR followed by DNA sequencing. Conjugation, plasmid profiling and targeted PCR were performed to demonstrate the transferability of the qnrS1 gene. Subsequently, a plasmid was identified that carried a quinolone resistance marker and this was completely sequenced.
  
  
  RESULTS
  A Salmonella Virchow isolate carried a qnrS1 gene associated with an IncN incompatibility group conjugative plasmid of 40 995 bp, which was designated pVQS1. The latter conferred resistance to ampicillin and nalidixic acid and showed sequence similarity in its core region to plasmid R46, whilst the resistance-encoding region was similar to pAH0376 from Shigella flexneri and pINF5 from Salmonella Infantis and contained an IS26 remnant, a complete Tn3 structure, a truncated IS2 element and a qnrS1 marker, followed by IS26. In contrast to pINF5, IS26 was identified immediately downstream of the qnrS1 gene.
  
  
  CONCLUSIONS
  This is the first known report of a qnrS1 gene in Salmonella spp. in Switzerland. Analysis of the complete nucleotide sequence of the qnrS1-containing plasmid showed a novel arrangement of this antibiotic resistance-encoding region.
authors.affiliation: UCD Centre for Food Safety & Centre for Food-borne Zoonomics, UCD Veterinary Sciences Centre,  School of Public Health, Physiotherapy & Population Science, University College Dublin, Belfield, Dublin 4,  Ireland.
authors.forename: Maria
authors.initials: M
authors.lastname: Karczmarczyk
authors.forename: Roger
authors.initials: R
authors.lastname: Stephan
authors.forename: Herbert
authors.initials: H
authors.lastname: Hächler
authors.forename: Séamus
authors.initials: S
authors.lastname: Fanning
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D022761:Gene Transfer, Horizontal; D006801:Humans; D008969:Molecular Sequence Data; D010957:Plasmids / Q000032:analysis*; D016133:Polymerase Chain Reaction; D015363:Quinolones / Q000494:pharmacology*; D012480:Salmonella Infections / Q000382:microbiology*; D019779:Salmonella enterica / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013557:Switzerland; D014195:Travel
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D015363:Quinolones