Use of molecular techniques for the detection of quinolone resistance in pseudomonas aeruginosa

Pseudomonas aeruginosa is responsible for serious infections in critically ill patients. In recent years, increasing antimicrobial resistance in both nosocomial and community acquired P. aeruginosa isolates is alarming.The aim of study was to detect the quinolone resistance of P. aeruginosa strains isolated from various clinical specimens in our hospital, by conventional and molecular metods. Ninety ? three nonfermentative bacterial isolates were included in the study. Thirty ? nine of them was identified as P. aeruginosa by using conventional metods. Ofloxacin susceptibility of the stains were assessed by using agar dilution method according to the recommendations of CLSI and DNA sequencing of gyrA was done.Fourteen of 39 (35,89%) P. aeruginosa strains were resistant to ofloxacin. Further 3 (7,69%) strains were found intermediate ? resistant. The substitution of threonine to isoleucine was observed in 5 of 14 (35.71%) quinolone resistant strains. Various silent mutations had been detected in quinolone resistant and susceptible strains, where codon 132 was most frequently affected. None of the susceptible strains had missense or nonsense mutations in gyrA. Six of 39 (12,82%) of the strains did not have any gyrA mutations.These data confirm that the primary mechanism of quinolone resistance in P. aeruginosa is mediated through target site alterations, specifically leading to the amino acid substitution of an isoleucine for a threonine in gyrA.To our knowledge this is the first study which the quinolone resistance examined by molecular analyzes in the gyrA gene of the P. aeruginosa in Turkey.We requirement new studies for clarifying the antimicrobial resistance because of the high level resistance in P. aeruginosa. The gene region must examined which can be related with resitance this is necessary for showing molecular chracteristic.