鲍曼不动杆菌耐药表型与外排泵基因表达水平的研究

目的 探讨鲍曼不动杆菌临床分离株对常用抗菌药物的耐药性及与外排泵adeA基因表达水平之间的关系.方法 琼脂二倍稀释法检测鲍曼不动杆菌临床分离株对17种常用抗菌药物的最低抑菌浓度(MIC);PCR法扩增外排泵编码基因adeA:实时荧光定量RT-PCR(Real Time Fluorescent Quantitative RT-PCR)法检测adeA基因的mRNA表达水平.结果 药敏结果显示86株鲍曼不动杆菌对多粘菌素B全部敏感(100%),其次是美罗培南(73.2%)、亚胺培南(70.9%).耐药率最高的是庆大霉素(84.9%),其次为美罗西林(83.7%)和环丙沙星(79.1%).55株菌为多重耐药株(64%),其中5株(5/86)对多粘菌素B外的所有抗菌药物耐药(5.8%).adeA的检出阳性率为84.9%(73/86),Real Time RT-PCR结果显示多重耐药菌株adeA基因的mRNA相对表达量均高于敏感菌株,其中3株相对表达量为敏感菌株平均表达水平的30倍以上.结论 鲍曼不动杆菌临床分离株耐药情况严重,其主动外排系统adeA基因表达增强在多重耐药性形成中起重要作用.

Investigation of resistance phenotype in relation to efflux pump gene expression in Acinetobacter baumannii clinical isolates

Objective To investigate the relationship between the resistance phenotype and the expression of efflux pump gene adeA in Acinetobacter baumannii.Methods The minimal inhibitory concentrations(MICs)of 17 antimicrobial agents against 86 Acinetobacter baumannii clinical isolates were determined by agar dilution method.PCR was used to detect the adeA gene and the mRNA expression of adeA gene were quantified by real time fluorescent quantitative RT-PCR.Results The susceptible rate ofpolymyxin B was the highest(100%),carbapenems (meropenem,imipenem)were the second(73.2%and 70.9%,respectively).The resistant rate of gentamicin,mezlocillin,and ciprofloxacin was 84.9%,83.7%and 79.1%,respectively.The incidence of multidrug resistance was 64%(55/86).5 strains were resistant to all the antimicrobial agents except polymyxin B.84.9%(73/86)of the isolates detected was positive in adeA.The result of real time RT-PCR in seven multidrug resistant strains showed that the levels of mRNA expression of adeA gene in mutidrug resistant strains were higher compared with the susceptible ones.Conclusions Most isolates are highly resistant to most of the antibacterial agents commonly used.High levels of mRNA expression of adeA gene in Acinetobacter baumannii play an important role in multidrug resistance.