Prevalence and fluoroquinolone resistance of pseudomonas aeruginosa in a hospital of South China.

Pseudomonas aeruginosa is an opportunistic pathogen that poses a threat in clinical settings. This study aimed to investigate the molecular characterization and epidemiology of fluoroquinolones (FQs) resistance in P. aeruginosa isolated from South China. A total of 256 P. aeruginosa strains isolated from outpatients, emergency patients and inpatients were collected from January 2010 to December 2010 in the hospital of South China. The resistance profile of all isolated strains was screened by antibiotic-susceptibility testing, and the molecular characteristics of plasmid-mediated quinolone resistance (PMQR) and the quinolone resistance determining region (QRDR) were determined using PCR in combination with DNA sequencing. The result of antibiotic-susceptibility tests showed that most strains were sensitive to polymyxin B, piperacillin, piperacillin/tazobactam, ceftazidime and amikacin. Moreover, 65 isolates were identified as resistant to ciprofloxacin. Further analysis of QRDR revealed that the resistant strains carried at least one mutation in the gyrA (The83Ile), gyrB (Ser467Phe, Gln468His) and parC (Ser87Leu) genes, but no mutation was detected in parE. For the first time, we report here that the qnrA1 gene is associated with low levels of resistance to ciprofloxacin from clinical P. aeruginosa isolates in South China. The mutation of gyrA (at position 83) is clearly linked to the FQs resistance of P. aeruginosa. Moreover, FQs resistance of P. aeruginosa may be due to the chromosome-mediated resistance mechanism rather than PMQR.