铜绿假单胞菌的耐药性及其耐氟喹诺酮机制的研究

Drug Resistance of Pseudomonas aeruginosa and Mechanisms of Its Resistance to Fluoroquinolones

目的 了解铜绿假单胞菌的耐药性及其耐氟喹诺酮的机制。方法 用纸片扩散法测定 6 2 6株铜绿假单胞菌对 11种抗生素的耐药性 ,琼脂稀释法测定 4 0株耐环丙沙星的铜绿假单胞菌对环丙沙星和左氧氟沙星的最低抑菌浓度 (MIC) ,聚合酶链反应 -限制性长度多态性分析检测耐环丙沙星的铜绿假单胞菌的 gyr A基因和 par C基因突变。结果 6 2 6株铜绿假单胞菌中耐环丙沙星的 180株 (2 8.8% ) ,耐左氧氟沙星的 2 19株 (35 .0 % ) ,4 0株耐环丙沙星的铜绿假单胞菌有 30株 (75 % )发生 gyr A基因 83位点突变 ,2 6株 (6 5 % )发生 par C基因 87位点突变 ,两种突变同时发生的 2 5株 (6 2 .5 % )。结论 铜绿假单胞菌的耐药性日趋严重 ,临床分离的铜绿假单胞菌耐氟喹诺酮的机制大多为药物作用靶位 gyr A和 par C的基因突变。

OBJECTIVE To investigate the drug resistance of Pseudomonas aeruginosa (PAE) and mechanisms of its resistance to fluoroquinolones. METHODS The susceptibility of 626 strains of PAE to 11 antibiotics was detected by disc diffusion. The minimal inhibitory concentrations(MICs) of forty strains to ciprofloxacin and levofloxacin were determined by agar dilution method. Forty strains resistant to ciprofloxacin were studied for the presence of point mutations in gyrA gene and parC gene by polymerase chain reaction restriction fragment length polymorphisms (PCR RFLP) method. RESULTS In 626 strains of PAE, 180 strains resistant to ciprofloxacin(28.8%), 219 strains resistant to levofloxacin(35.1%). In 40 strains of PAE resistant to ciprofloxacin, 30 strains (75%) had mutation at gyrA codon 83 and 26 strains (65%) had mutation at parC 87; 25 strains (62.5%) had containing mutation in gyrA gene and parC gene. The susceptible to ciprofloxacin P. aeruginosa had not mutation. CONCLUSIONS It is clear that emergence of resistant PAE strains will continue to be a problem. The resistance to fluoroquinolones in clinical isolates of PAE is due to the mutations of the gyrA and parC gene encoding the target enzyme of fluoroquinolones.