MexAB-OprM和MexXY-OprM在耐药铜绿假单胞菌中的表达

目的探讨MexAB-OprM和MexXY-OprM主动外排系统与铜绿假单胞菌多重耐药的关系。方法挑选临床分离的铜绿假单胞菌敏感株和多重耐药株各30株,以及标准质控株,用RT-PCR扩增其mexB、mexY和核糖体参照基因rpsL片段,根据mexB、mexY与rpsL扩增产物的电泳扫描比值,分析mexB与mexY mRNA的表达水平。结果标准株、所有敏感株和多重耐药株均检测出mexB、mexY的mRNA基因,耐药株的mexB、mexY mRNA水平显著高于敏感株(P<0.05)。结论MexAB-OprM和MexXY-OprM主动外排系统与铜绿假单胞菌固有耐药有关,其表达水平异常增高与多重耐药形成密切相关。     

海南某三甲医院多重耐药铜绿假单胞菌MexAB-OprM、MexCD-OprJ、MexEF-OprN、MexXY-OprM表达及与耐药表型的关系研究

目的探讨多重耐药铜绿假单胞菌(Pseudomonas aeruginosa,Pa)MexAB-OprM、MexCD-OprJ、MexEF-OprN、MexXY-OprM的表达及其与耐药表型的关系。方法选取2016年9月至2018年10月儋州市人民医院微生物培养室分离的Pa 54株,采用琼脂稀释法测定14种抗菌药物的MIC,加外排泵抑制剂苯丙氨酸-精氨酸-β萘酰胺(PAβN)进行干预实验,实时荧光定量PCR检测膜融合蛋白mexA、mexC、mexE、mexX的mRNA表达水平,以判断MexAB-OprM、MexCD-OprJ、MexEF-OprN、MexXY-OprM的表达情况,PCR扩增调控基因mexR、nfxB、mexT、mexZ对扩增产物进行测序,使用Blast软件在GenBank上与已知序列进行比对。结果RT-PCR检测发现,耐药菌株中18株(33.33%)Pa高表达MexAB-OprM外排系统,9株(16.67%)高表达MexCD-OprJ外排系统,12株(22.22%)高表达MexEF-OprN外排系统,14株(25.93%)高表达MexXY-OprM外排系统。抑制剂作用下18株MexAB-OprM外排泵高表达Pa株对头孢噻肟、庆大霉素、环丙沙星的MIC为2~64μg/ml,9株MexCD-OprJ高表达株中6株对头孢噻肟的敏感性MIC为2~128 mg/ml,12株MexEF-OprN中对环丙沙星、亚胺培南的敏感性MIC为4~128 mg/ml,14株MexXY-OprM为庆大霉素、环丙沙星高度耐药菌株。分别随机选择mexA、mexC、mexE、mexX高表达菌株中的4个菌株,mexR高表达菌株中发生3个mexR基因突变;4个nfxB高表达菌株中均发生82位的突变;4个mexT高表达菌株中均发生26位的突变;2个mexZ高表达菌株发生138位的突变,1个发生50位的突变。结论主动外排系统MexAB-OprM、MexCD-OprJ、MexEF-OprN、MexXY-OprM过度表达是Pa多重耐药机制之一,同时与其调控基因mexR、nfxB、mexT、mexZ发生突变相关。     

Intrinsic resistance of Escherichia coli to mureidomycin A and C due to expression of the multidrug efflux system AcrAB-TolC: comparison with the efflux systems of mureidomycin-susceptible Pseudomonas aeruginosa

 Intrinsic resistance to mureidomycin is shown in Escherichia coli. This is in contrast to Pseudomonas aeruginosa, which generally displays intrinsic resistance to a variety of antimicrobial agents, but not to mureidomycin. Isogenic efflux system mutants from both species were subjected to antibiotic susceptibility tests. These studies showed that the differences regarding the susceptibility of E. coli and P. aeruginosa to mureidomycin A and C may be explained by the expression of efflux systems that mediate resistance to mureidomycin A and C. Received: July 22, 2002 / Accepted: September 24, 2002 Acknowledgments We thank Masatoshi Inukai (Sankyo Co., Japan) for providing mureidomycin A and C, and we thank Keith Poole (Queen's University, Canada) and Jun-ichi Yamagishi (Dainippon Pharmaceutical Co., Japan) for providing the K and SH strains of E. coli, respectively. This research was supported by grants for scientific research to N.G. from The Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, and from the Ministry of Health, Labor, and Welfare of Japan. T.M. was the recipient of a scholarship from The Japan Scholarship Foundation.