Chen Jing, Kuroda Teruo, Huda Md Nazmul, Mizushima Tohru, Tsuchiya Tomofusa
Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama 700-8530, Japan.
J Antimicrob Chemother. 2003 Aug;52(2):176-9. doi: 10.1093/jac/dkg308. Epub 2003 Jul 1.
Serratia marcescens, an important cause of nosocomial infections, shows intrinsic resistance to a wide variety of antimicrobial agents (multidrug resistance). Multidrug efflux pumps are often involved in the multidrug resistance in many bacteria. A study was undertaken to characterize the multidrug efflux pumps in S. marcescens.
The genes responsible for the multidrug resistance phenotype in S. marcescens were cloned into Escherichia coli KAM32, a drug-hypersusceptible strain, for further analysis.
We cloned sdeXY genes and determined the nucleotide sequence. Clones that carried the sdeXY genes displayed reduced susceptibility to several antimicrobial agents including erythromycin, tetracycline, norfloxacin, benzalkonium chloride, ethidium bromide, acriflavine and rhodamine 6G. A protein similarity search using GenBank revealed that SdeY is a member of the resistance nodulation cell-division (RND) family of multidrug efflux proteins and SdeX is a member of the membrane fusion proteins. Introduction of sdeXY into E. coli cells possessing tolC, but not in cells lacking tolC, resulted in multidrug resistance. We observed energy-dependent ethidium efflux in cells of E. coli KAM32 possessing sdeXY and tolC.
SdeXY is the first RND-type multidrug efflux pump to be characterized in multidrug-resistant S. marcescens.
粘质沙雷氏菌是医院感染的重要病原菌，对多种抗菌药物表现出固有耐药性（多重耐药）。多药外排泵通常与许多细菌的多重耐药性有关。本研究旨在对粘质沙雷氏菌中的多药外排泵进行特性分析。
将负责粘质沙雷氏菌多重耐药表型的基因克隆到药物超敏感菌株大肠杆菌KAM32中，以进行进一步分析。
我们克隆了sdeXY基因并测定了其核苷酸序列。携带sdeXY基因的克隆对包括红霉素、四环素、诺氟沙星、苯扎氯铵、溴化乙锭、吖啶黄素和罗丹明6G在内的多种抗菌药物的敏感性降低。使用GenBank进行的蛋白质相似性搜索显示，SdeY是多药外排蛋白耐药结节化细胞分裂（RND）家族的成员，SdeX是膜融合蛋白的成员。将sdeXY导入含有tolC的大肠杆菌细胞中会导致多重耐药，而导入缺乏tolC的细胞中则不会。我们在含有sdeXY和tolC的大肠杆菌KAM32细胞中观察到了能量依赖性的溴化乙锭外排。
SdeXY是首个在多重耐药粘质沙雷氏菌中得到特性分析的RND型多药外排泵。
