title: Plasmid-mediated quinolone resistance in typhoidal Salmonellae: a preliminary report from South India.
abstract: BACKGROUND
  Fluoroquinolones are the drugs extensively employed for the treatment of Salmonella infections. Over the couple of decades that have elapsed since the introduction of fluoroquinolones, resistance to these agents by Enterobacteriaceae family members has become common and widespread. Although fluoroquinolone resistance is mediated by genomic DNA (deoxyribonucleic acid) as well as plasmid DNA, the plasmid-mediated quinolone resistance (PMQR) facilitates higher level resistance by interacting with genomic mechanism and is capable of horizontal spread.
  
  
  METHODS
  During a period of 1-year, 63 typhoidal Salmonellae were isolated from 14,050 blood cultures and one parietal wall abscess. 36 (56.25%) were Salmonella Typhi and 27 (42%) were Salmonella Paratyphi A. They were all screened for resistance by the disc diffusion method and their minimum inhibitory concentrations were determined using agar dilution, broth dilution and E-strip method. Ciprofloxacin resistant isolates were screened for PMQR determinants by polymerase chain reaction assay.
  
  
  RESULTS
  All the 63 isolates were resistant to nalidixic acid. Among the 36 S. Typhi isolates 20 were resistant to ciprofloxacin, of which 14 carried the plasmid gene qnrB and one carried the aac(6')-Ib-cr gene. qnrA and qnrS genes were not detected. Ciprofloxacin resistance was not seen in any of the S. Paratyphi A isolates.
  
  
  CONCLUSIONS
  The antibiotic sensitivity pattern of typhoidal Salmonellae shows an increasing trend of PMQR. The allele B of qnr gene was found to be the predominant cause of PMQR in this study.
authors.forename: V K
authors.initials: VK
authors.lastname: Geetha
authors.forename: T
authors.initials: T
authors.lastname: Yugendran
authors.forename: R
authors.initials: R
authors.lastname: Srinivasan
authors.affiliation: Department of Microbiology, Jawaharlal Institute of Post Graduate Medical Education and Research, Gorimedu, Puducherry, India.
authors.forename: B N
authors.initials: BN
authors.lastname: Harish
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D006801:Humans; D007194:India / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D010284:Paratyphoid Fever / Q000453:epidemiology / Q000382:microbiology*; D010957:Plasmids; D016133:Polymerase Chain Reaction; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D012482:Salmonella paratyphi A / Q000187:drug effects* / Q000302:isolation & purification; D012485:Salmonella typhi / Q000187:drug effects* / Q000302:isolation & purification; D014435:Typhoid Fever / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D015363:Quinolones