铜绿假单胞菌的临床分布及对环丙沙星耐药机制的研究

目的 分析医院铜绿假单胞菌（PAE）的临床分布和耐药性,并了解其对环丙沙星的耐药机制.方法 我院2011年9月-2013年9月收集的287株铜绿假单胞菌.采用琼脂纸片扩散法（K-B法）进行药敏试验,微量肉汤稀释法测定环丙沙星对PAE的最低抑菌浓度（MIC）.应用PCR方法扩增PAE的gyrA、gyrB、parC及parE基因,并测序来确定基因的突变.结果 287株铜绿假单胞菌以痰液标本中分离最多（76.3％）;主要感染分布在重症监护室（29.3％）和呼吸内科（22.6％）;且对哌拉西林/他唑巴坦及亚胺培南敏感,敏感率均在70％以上;而对氨苄西林及环丙沙星耐药率高,分别达97.9％和44.9％.在45株（环丙沙星MICs≥32 μg/ml）铜绿假单胞菌中,有42株均存在gyrA基因突变,且28株存在着gyrA基因和parC基因双突变.结论 铜绿假单胞菌多重耐药现象严重,gyrA基因突变是PAE对环丙沙星耐药的主要机制之一.应加强对铜绿假单胞菌的临床分布及耐药性监测,更好地指导临床合理用药,控制医院感染.

Clinical distribution and drug resistance mechanisms to ciprofloxacin of 287 strains of pseudomonas aeruginosa

Objective To analyze the clinical distribution and drug resistance of pseudomonas aeruginosa （PAE）,and explore the drug resistance mechanisms of ciprofloxacin resistant of PAE.Methods 287 strains of PAE were col lected from the hospital patients from Sep 2012 to Sep 2013.Drug resistance testing were performed by K-B disk diffusion method,and minimal inhibitory concentrations （MICs） of ciprofloxacin to PAE were determined by broth micro-dilution method.Genes gyrA,gyrB,parC and parE of PAE were amplified by PCR,then the PCR products were sequenced to identify the mutations in these genes.Results 76.3％ P.aeruginosa were isolated from sputum,PAE infection were mostly occurred in ICU （29.3％） and following by department of respiratory diseases （22.6％） ;PAE had a high susceptibility to piperacillin/tazobactam and imipenem,the sensitive rate were over 70.0％;While PAE had the highest resistant rate to ampicillin （97.9 ％）,following by ciprofloxacin （44.9 ％）.Among the 45 PAE isolates （MIC of ciprofloxacin≥32 μg/ml）,gyrA gene mutations were found in 42 strains,and double mutations of gyrA and parC genes were found in 28 strains.Conclusion Pseudomonas aeruginosa is multi drug resistance,mutation of gyrA gene is one if the main resistant mechanisms of PAE to ciprofloxacin.It＇s necessary to reinforce the monitoring on clinical distribution and drug resistance of PAE,to guide the rational clinical drug usage and control the emergence of drug resistant strains.