阴沟肠杆菌质粒pB557-NDM全序分析及耐药机制研究  

Genomic characteristics and antibiotic-resistant mechanisms of plasmid pB557-NDM isolate from Enterbacter cloacae

作　　者：李萍[1,2] 冯娇[2] 康琳[2] 辛文文[2] 高珊[2] 杨浩[2] 周冬生[2] 殷喆[2] 王景林[1,2] LI Ping FENG Jiao KANG Lift XIN Wen-wen GAO Shan YANG Hao ZHOU Dong-sheng YIN Zhe WANG Jing-lin(Anhui Medical University, Hefei 230032, China State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, China)

机构地区：[1]安徽医科大学,合肥230032 [2]军事医学科学院微生物流行病研究所,病原微生物生物安全国家重点实验室,北京100071

出　　处：《军事医学》2016年第12期964-968,973,共6页Military Medical Sciences

基　　金：国家重点研究计划重点专项(2016YFC1200104);国家高技术研究发展计划(2014AA021402)

摘　　要：目的对阴沟肠杆菌质粒pB557-NDM全序进行分析并研究其耐药机制。方法 PCR方法检测相关菌株耐药基因,改良Carba NP法检测碳青霉烯酶类型及其活性,接合转移实验验证质粒pB557-NDM是否具有可转移性,抗生素敏感实验检测相关菌株耐药谱,质粒全基因组测序分析其遗传结构、移动元件,对其耐药机制进行研究。结果阴沟肠杆菌B557产B类碳青霉烯酶,编码NDM的基因blaNDM位于质粒pB557-NDM上。pB557-NDM可通过接合转移方式进入受体菌EC600并表达相应的耐药谱。质粒pB557-NDM为大小141.65 kb的Inc A/C2型质粒,Gen Bank登录号为KX786648。该质粒共有2个外源插入区,分别为ISEcp1-blaCMY转座单元形成的blaCMY-6耐药区和ΔTn1696-In46-rmt C-ISKpn14-ΔTn125组成的blaNDM-1耐药区。结论质粒pB557-NDM介导阴沟肠杆菌B557多药耐药,blaNDM位于转座子ΔTn125中。Objective To characterize the whole-sequence of plasmid pB557-NDM isolate from Enterbacter cloacae and elaborate its antibiotic-resistant mechanisms. Methods Antibiotic resistance genes were determined by PCR, followed by amplicon sequencing. The activity of class A/B/D carbapenemases was determined by modified Carba NP test. Conjugation experiments were performed to verify the transferability of plasmid pB557-NDM. The minimum inhibitory concentration （MIC） values of bacterial strains were tested using VITEK 2. The genetic structure, mobile elements and antibiotic- resistant mechanisms of transferable plasmid pB557-NDM were determined by a whole genome sequencing method. Results The modified CarbaNP test showed that B557 and B557-EC600 had class B carbapenemase activity, and that the blaNDM was carried by plasmid pB557-NDM. This plasmid could be transferred into E. coli through conjugation experiments and therefore could confer corresponding antibiotic resistances to the transcoujugant B557-EC600. Plasmid pB557-NDM was an IncA/C2 plasmid, whose total length was 141.65 kb, and the GenBank accession number was KX786648. It had two inserted regions. One was the blaCMY-6 region where the blaCMY gene was carried by a transposition unit ISEcpI-blaCMY, the other was the blaNDM-1 region which consisted of a ΔTn1696-In46-rmtC-ISKpn14-ΔTn125 complex structure. Conclusion The production of plasmid pB557-NDM in strain B557 contributes most to its high resistance to many antibiotics. The blaNDM-1 gene is carried in a trancated transposition ΔTn125.

关 键 词：阴沟肠杆菌 pB557-NDM 碳青霉烯酶 

分 类 号：R446.5[医药卫生—诊断学]