铜绿假单胞菌耐药率与多位点序列分型研究

Antibiotic resistance rate and multilocus sequence typing of Pseudomonas aeruginosaisolates

目的研究铜绿假单胞菌的耐药率与分子流行病学规律，明确其进化特征，为临床抗菌药物的合理应用提供依据。方法2010年6月-2012年10月对168株铜绿假单胞菌开展体外药物敏感性试验与多位点序列分型（MLST）研究，并应用BioNumerics与START2软件进行生物信息学分析，以揭示其流行趋势。结果MLST方案中选取的7个管家基因GC含量分布达60．0％～70．0％；各等位基因数分布于4～10个，aroE的等位基因数只有4个，而acsA的等位基因数有10个，trpE的多态性位点最多，为16个；168株铜绿假单胞菌对除多黏菌素外的抗菌药物耐药率为16．3％～35．2％；MLST结果显示，全部菌株共形成20个ST型，其中ST244有26株、ST986有22株、ST597有16株、ST441有13株，上述4个ST型均属于克隆复合体CC244，此外，研究还发现5个新ST型。结论铜绿假单胞菌对临床常用抗菌药物的耐药率较高，呈现多药耐药趋势；铜绿假单胞菌的传播趋势以散发为主，其进化速度较快，但在医院抗菌药物选择压力的作用下也易形成典型的克隆复合体，目前需要重点监控以CC244为代表的铜绿假单胞菌的流行，以防其在医院内大规模暴发与流行。

OBJECTIVE To investigate the resistant rate of Pseudornonas aeruginosa to several antibiotics and its molecular epidemiology, explore the evolutionary characteristics, and provide basis for clinical use of antibiotics. METHODS One hundred and sixty-eight P. aeruginosa isolates were collected to perform antibiotic susceptibility testing and multilocus sequence typing （MLST） during Jun. 2010 to Oct. 2012. MLST data were analyzed by BioNumerics andi START2 software to reveal the prevalence pattern. RESULTS The GC content of seven housekeeping genes included in MLST scheme were about 60.0%- 70.0%. The number of alleles ranged from four to ten, and aroE only had four alleles, whereas acsA had ten. Besides, trpE possessed the most polymorphism sites of sixteen. The resistance rates were 16. 3% - 35. 2% for 168 isolates to ten antibiotics except polymyxin. The MLST research indicated that all isolates clustered into 20 STs, including 26 isolates in ST244, 22 isolates in ST986, 16 isolates in ST597, 13 isolates in ST441, which were clustered into one clonal complex CC244. Moreover, there were five novel STs. CONCLUSION The resistance rates to clinical antimicrobials are relatively high for P. aeruginosa, and the multiple-drug resistance emerges. Besides, the dissemination pattern of P. aeruginosa is somehow diverse with a fast evolution speed. However, it could also form a typical clone complex easily under the nosoeomial antibiotic selection pressure. In the current situation, clinicians still need to monitor the prevalence of CC244 for representation of P. aeruginosa and prevent its major outbreak and prevalence in our hospital.