左氧氟沙星和美洛培南体外诱导铜绿假单胞菌耐药的外排机制研究  

Investigation of induced resistance by Levofloxacin and Meropenem in vitro and the resistant mechanism of efflux pumps in Pseudomonas aeruginosa

作　　者：曹敬荣[1] 沈定霞[1] 白立彦[1] 宋海英[1] 周光[1] 

机构地区：[1]解放军总医院微生物科,北京100853

出　　处：《中国药物应用与监测》2007年第6期25-28,共4页Chinese Journal of Drug Application and Monitoring

基　　金：军队"十一五"基金资助课题(06MA294)

摘　　要：目的:研究左氧氟沙星和美洛培南对铜绿假单胞菌耐药的诱导作用及诱导耐药的外排机制。方法:多步诱导法对3株铜绿假单胞菌进行诱导耐药试验,对诱导出的菌株用微量肉汤稀释法测定加与不加外排泵抑制剂(苯丙氨酸-精氨酸-!萘酰胺)的最小抑菌浓度(MIC)的变化,PCR法检测外排泵基因oprM和mexB,并扩增mexR基因进行DNA测序。结果:3株菌均诱导出稳定的耐左氧氟沙星和美洛培南的耐药株,MIC值与原菌比较分别增加了16倍～64倍和2倍～16倍,加外排泵抑制剂后左氧氟沙星的MIC值降低了4倍～8倍;3株菌诱导前后均扩增出外排泵基因oprM和mexB,mexR测序结果与GenBankU23763比较,核苷酸序列第222位(C→T),氨基酸序列(CTG→TTG)均为LEU,为无义突变,核苷酸序列第436位插入1bp(A)移码框。结论:左氧氟沙星和美洛培南可诱导铜绿假单胞菌产生获得性耐药,其耐药机制与主动外排相关。Objective：To investigate the induced resistance and the mechanism of efflux pumps in P.aeruginosa.Methods：Induced resistance to Levofloxacin and Meropenem was performed by multiple-step method in 3 strains of P.aeruginosa.The susceptibility of the induced strains resistant to LVX and MEP was measured by detecting the MICs using microdilution method.The MICs were checked with and without efflux pump inhibitors （Phe-Arg-β-naphthylamide）.The efflux pump genes of oprM and mexB were ampli- fied by PCR, then the nucleotide sequence of mexR gene was analyzed.Results：The strains highly resistant to Levofloxacin and Meropenem were obtained from all 3 P.aeruginosa strains.The MICs of these laboratory resistant strains to Levofloxacin and Meropenem were 16 to 64-told and 2 to 16-fold increase, respectively, compared with parent strains.The M1Cs to LVX were 4 to 8-fold decrease in the presence of efflux pump inhibitors.Specific bands of mexB and oprM were detected from both of parent and induced strains.MexR gene sequence showed a C to T substitution at nucleotide 222 resulting in a nonsence mutation and a lbp （A） insertion at nucleotide 436 resulting in a frame shift comparing with GenBank accession number U23763.Conchltsion：The acquired resistance of P.aeruginosa to Levofloxacin and Meropenem could be induced in vitro, the efflux pump maybe play a role in some resistant strains.

关 键 词：铜绿假单胞菌 体外诱导耐药 主动外排 左氧氟沙星 美洛培南 

分 类 号：R96[医药卫生—药理学]