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目的:探讨临床分离的铜绿假单胞菌的主动外排系统MexAB-OprM与其对碳青霉烯类药物耐药之间的关系,研究其耐药分子机理。方法:测定临床分离的铜绿假单胞菌对亚胺培南和美罗培南的体外抗菌活性,根据耐药情况,分为碳青霉烯类药物敏感组和碳青霉烯类药物耐药组;应用RT-PCR方法,研究两组菌株的主动外排系统MexAB-OprM中结构基因oprM的mRNA表达水平;用PCR法扩增两组菌株的泵调节基因mexR,对扩增产物进行DNA双向测序。结果:耐药组oprM的mRNA表达水平明显高于敏感组(P<0.05);一株菌发现MexR第126位氨基酸突变(缬氨酸→谷氨酸),两株菌发现MexR第70位氨基酸突变(精氨酸→谷氨酰胺)。结论:山西医科大学第一医院临床分离铜绿假单胞菌的主动外排系统MexAB-OprM参与碳青霉烯类药物的耐药;MexAB-OprM高表达的分子机理可能与泵调节基因mexR的突变以及其他突变型有关。
OBJECTIVE: To investigate the relationship between MexAB-OprM, an active efflux system of Pseudomonas aeruginosa, and its resistance to carbapenems, and to study its molecular mechanism of drug resistance. Methods: The antibacterial activity of clinically isolated Pseudomonas aeruginosa against imipenem and meropenem in vitro was determined and divided into carbapenem-sensitive group and carbapenem-resistant group according to drug resistance. RT-PCR method was used to study the mRNA expression level of oprM in MexAB-OprM, the active efflux system of the two strains. The mexR gene was amplified by polymerase chain reaction (PCR) and sequenced. Results: The mRNA level of oprM in resistant group was significantly higher than that in susceptible group (P <0.05). One strain found a mutation of amino acid at position 126 of MexR (valine → glutamic acid), and the two strains found that the 70th amino acid of MexR Mutation (arginine → glutamine). Conclusion: MexAB-OprM, an active efflux system of Pseudomonas aeruginosa isolated from the First Hospital of Shanxi Medical University, is involved in the resistance of carbapenems. The molecular mechanism of MexAB-OprM overexpression may be related to the mutation of pump-regulated gene mexR And other mutations related.