European Journal of Biomedical and Pharmaceutical Sciences

EMERGENCE OF PLASMID-MEDIATED QUINOLONE RESISTANCE (PMQR) DETERMINANT FROM CLINICAL ISOLATES OF PSEUDOMONAS AERUGINOSA

*Dhiraj Kumar Sah and Lavanya Mohanam

ABSTRACT

Introduction: Due to intrinsic resistance of Pseudomonas aeruginosa to many antibacterial agents, treatment of pseudomonal infections are difficult. Ciprofloxacin is the most effective quinolone against P. aeruginosa infection. However resistance developing to quinolones may become an important problem and is often a result of chromosomal mutations and by the effect of efflux pumps. Although there are reports on the plasmid-mediated quinolone resistance (PMQR) inthe members of Enterobacteriaceae family, they have not been detected in P. aeruginosa isolates until now. Hence this study was designed to determine the PMQR determinant in P. aeruginosa. Objectives: The aim of the study was to investigate the occurrence of PMQR determinant in clinical isolates of P. aeruginosa by phenotypic and molecular methods. Materials and Methods: A total of 34 strains of P. aeruginosa isolated from various clinical specimens such as pus (82.3%), urine (14.7%) and blood (2.9%) were included in the study. All isolates were tested for susceptibility to the following fluroquinolones: ciprofloxacin, levofloxacin and ofloxacin by Kirby Bauer disc diffusion method. MIC of ciprofloxacin was determined by agar dilution method according to CLSI guidelines. DNA extraction was done by boiling lysis method. Molecular detection of PMQR determinants (qnr A, qnr B and qnr S) was done for all the isolates. Results: Disc diffusion tests showed resistance to ciprofloxacin, levofloxacin and ofloxacin. Of the 34 isolates screened, qnr A and qnr S genes were not detected in any of the tested isolates. 25(73.5%) isolates were positive for qnr B gene and these isolates showed MIC ranging from 32 μg/ml to 256μg/ml. Conclusion: Plasmid mediated quinolone resistance genes have so far not been identified in P. aeruginosa. However, recent studies have detected qnr B in P. fluorescens and P. putida. This is the first report of qnr B gene identified in P. aeruginosa clinical isolates.

Keywords: P. aeruginosa, fluroquinolones: ciprofloxacin, levofloxacin and ofloxacin.