title: Identification of plasmid-mediated quinolone resistance genes qnrA1, qnrB1 and aac(6')-1b-cr in a multiple drug-resistant isolate of Klebsiella pneumoniae from Chennai.
abstract: OBJECTIVE
  Resistance to fluoroquinolones, a commonly prescribed antimicrobial for Gram-negative and Gram-positive microorganisms, is of importance in therapy. The purpose of this study was to screen for the presence of Plasmid-Mediated Quinolone Resistance (PMQR) determinants in clinical isolates of Klebsiella pneumoniae.
  
  
  METHODS
  Extended-Spectrum Beta-Lactamase (ESBL) isolates of K. pneumoniae collected during October 2009 were screened by the antimicrobial susceptibility test. The plasmids from these isolates were analysed by specific Polymerase chain Reaction (PCR) for qnrA, qnrB and aac(6')-1b. The amplified products were sequenced to confirm the allele.
  
  
  RESULTS
  Our analysis showed that 61% out of the 23 ESBL K. pneumoniae isolates were resistant to ciprofloxacin and 56% to levofloxacin. The PMQR was demonstrated by transforming the plasmids from two isolates P12 and P13 into E. coli JM109. The PMQR gene qnrA was found in 16 isolates and qnrB in 11 isolates. The plasmid pKNMGR13 which conferred an minimum inhibitory concentration (MIC) of more than 240 μg/ml in sensitive E. coli was found to harbour the qnrA1 and qnrB1 allele. Furthermore, the gene aac(6')-1b-cr encoding a variant aminoglycoside 6'-N Acetyl transferase which confers resistance to fluoroquinolones was found in the same plasmid.
  
  
  CONCLUSIONS
  Our report shows the prevalence of PMQR mediated by qnrA and qnrB in multidrug-resistant K. pneumoniae isolates from Chennai. A multidrug-resistant plasmid conferring high resistance to ciprofloxacin was found to harbour another PMQR gene, aac(6')-1b-cr mutant gene. This is the first report screening for PMQR in K. pneumoniae isolates from India.
authors.affiliation: Department of Biotechnology, Dr. MGR Educational and Research Institute, Maduravoyal, Chennai - 600 095, Tamil Nadu, India.
authors.forename: H
authors.initials: H
authors.lastname: Magesh
authors.forename: C
authors.initials: C
authors.lastname: Kamatchi
authors.forename: R
authors.initials: R
authors.lastname: Vaidyanathan
authors.forename: G
authors.initials: G
authors.lastname: Sumathi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D007194:India; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000032:analysis; D016133:Polymerase Chain Reaction; D015363:Quinolones / Q000494:pharmacology*; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones