铜绿假单胞菌碳青霉烯耐药的机制研究

Mechanism of Pseudomonas aeruginosa carbapenem resistance

目的分析159株临床分离的非重复碳青霉烯耐药铜绿假单胞菌对抗菌药物的耐药性,探究体外联合药敏试验对碳青霉烯耐药铜绿假单胞菌表现不同作用的机制。方法收集来自不同患者的铜绿假单胞菌159株,亚胺培南及美罗培南耐药。采用三维水解试验检测β-内酰胺酶、聚合酶链式反应(PCR)等方法检测多重耐药菌可能存在的耐药机制。结果 159株临床分离的非重复碳青霉烯耐药铜绿假单胞菌,通过三维实验检测,其中15株产MBL、13株产AmpC酶。体外联合药物敏感试验,加入MC-207,110后约38%的菌株对碳青霉烯类抗生素的MIC下降4个梯度。检测试验菌株,21株携带IMP基因,18株携带ampC基因;检测OprD2通道蛋白,159株中约有48%的菌株OprD2丢失。结论北京友谊医院碳青霉烯耐药铜绿假单胞菌对碳青霉烯类抗生素耐药的主要原因不是IMP、AmpC水解酶;碳青霉烯耐药铜绿假单胞菌对碳青霉烯类抗生素耐药的重要原因可能是外排泵及外膜孔道蛋白。

Objective To investigate the drug resistance of 159 clinical isolates of earbapenem resistant Pseudomonas aeruginosa ,evalu- ate the in vitro activity of antimicrobials combinations against these Pseudomonas aeruginosa. To explore the related molecular mechanisms involved in different performances of combined antimicrebial sensitivity tests. Methods Totally 159 clinical isolates of Pseudomonas aeruginosa were col- lected from different patients in May 2010 to May 2011, by Clinical Laboratory Center of Beijing Friendship Hospital, Capital Medical University. Probable mechanisms of multi - drug resistance were determined through 3D hydrolysis test （ for detection of beta - lactamase ）, and polymerase chain reaction （ PCR）, etc. Results Moan - antibiotic MICs of the 159 carbapenem resistant Pseudomonas aeruginosa showed that these isolates were multi -drug resistant and less sensitive to drugs which were recommended by CLSI 2010 and used in daily clinical use, and they presented multi - drug resistance phenotypes. Three - dimensional experiments of the 159 carbapenem resistant Pseudomonas aeruginosa showed only 15 strains produced MBL, and 13 strains produced Ampc enzyme. In this study, we measured the in vitro drug susceptibility testing with the MC - 207,110 adding. 38% MICs of carbapenem antibiotics declined in four dilution gradients. And about 48% of the 159 strains lost the channel pro- tein OprD2. Conclusion The IMP and AmpC enzyme hydrolysis is not the main reason of Pseudomonas aeruginosas resistant. The loss of outer membrane pore proteins are crucial causes of carbapenem - resistant Pseudomonas aeruginosas production.