阿奇霉素对铜绿假单胞菌MexAB-OprM外排泵及耐药性的影响  

Effects of Azithromycin on MexAB-OprM Efflux Pump and Antibiotic Resistance in Pseudomonas aeruginosa

作　　者：夏超[1,2] 谢旭华[1] 王丽丽[1] 龚凤云[1] 宋莹[1] 宋建新[1] 

机构地区：[1]华中科技大学同济医学院附属同济医院感染科,武汉430030 [2]孝感市中心医院感染科,孝感432100

出　　处：《华中科技大学学报（医学版）》2012年第5期551-555,共5页Acta Medicinae Universitatis Scientiae et Technologiae Huazhong

基　　金：国家自然科学基金资助项目(No:30873189)

摘　　要：目的探讨阿奇霉素对铜绿假单胞菌MexAB-OprM外排泵的影响,为指导临床合理选择抗生素提供依据。方法排泵抑制剂(苯丙氨酸-精氨酸-β-萘酰胺PAβN)干预铜绿假单胞菌后,采用微量肉汤稀释法测定常见药物的最低抑菌浓度(minimal inhibitory concentration,MIC)值的变化,筛选主动外排表型阳性菌株。PCR扩增主动外排表型阳性菌株oprM、mexB和mexR;real-time PCR检测主动外排表型阳性菌株mexB的mRNA水平;对主动外排表型阳性菌株进行mexR基因测序分析。在阿奇霉素作用下,观察铜绿假单胞菌的mexB基因表达及对头孢他啶、左氧氟沙星、环丙沙星和美罗培南的MIC值变化。结果从20个临床多重耐药的铜绿假单胞菌菌株中筛选出8株主动外排表型阳性菌。检测表明这8株菌oprM、mexB和mexR均呈阳性,mexB的mRNA水平均较PAO1显著增高。对8株MexAB-OprM高表达菌mexR基因进行测序,发现菌株PAO03的mexR基因存在突变。阿奇霉素可显著降低mexR基因未突变MexAB-OprM高表达菌株的mexB基因的表达和对头孢他啶、左氧氟沙星、环丙沙星和美罗培南的MIC值,而对菌株PAO03和nalB突变株(mexR基因突变MexAB-OprM高表达菌株)无显著影响。结论阿奇霉素可抑制铜绿假单胞菌MexAB-OprM外排泵的表达,提高铜绿假单胞菌对抗生素的敏感性。Objective To investigate the influence of azithromycin on MexAB-OprM efflux pump in Pseudomonas aeruginosa in order to provide experimental evidence for reasonable choice of antibiotics in clinical work.Methods The minimal inhibitory concentration（MIC）of Pseudomonas aeruginosa to antibiotics was determined by broth microdilution after treated by efflux pump inhibitor（phenylalanine-arginine-β-naphthalene amide,PAβN）.The active efflux positive phenotype strains were chosen according to MIC.Three genes of efflux pumps,mexB,oprM and mexR,were detected by using PCR.Real-time PCR was used to detect the mRNA exression level of mexB in positive phenotype strains,while DNA sequencing was performed for mexR in the positive phenotype strains.After treated by azithromycin,the mRNA expression level of mexB and the MIC of antibiotics such as ciprofloxacin,levofloxacin,ceftazidime and meropenem were also tested in Pseudomonas aeruginosa.Results Eight positive phenotype strains were chosen from 20 clinical multidrug resistant strains of Pseudomonas aeruginosa.The oprM,mexB and mexR expression was confirmed in all 8 strains,whose expression of mexB mRNA was also significantly higher than that of PAO1.However,mexR mutations were found only in one strain,PAO03.Azithromycin significantly reduced the mexB expression and MICs of ciprofloxacin,levofloxacin,ceftazidime and meropenem in strains which overexpressed the MexAB-oprM but had no mexR mutation.However,the mexB expression and MICs in PAO03 and nalB strains were not influenced by azithromycin.Conclusion Azithromycin can suppress the gene expression of MexAB-OprM efflux pump,thus elevating the susceptibility of Pseudomonas aeruginosa to antibiotics.

关 键 词：铜绿假单胞菌 外排泵抑制剂 阿奇霉素 MEXAB-OPRM 

分 类 号：R915.11[医药卫生—微生物与生化药学]