Purpose: 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
.
Materials and 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 ΅g/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.
