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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 analyze the sequence of Enterobacter cloacae plasmid pB557-NDM and study its mechanism of drug resistance. Methods The resistant gene of related strains was detected by PCR method. The carbapenemase type and its activity were detected by modified Carba NP method. The conjugation and transfer experiments were carried out to verify whether the plasmid pB557-NDM could be transfected. The antibiotic susceptibility test was used to detect the resistant spectrum of the related strains. Genome sequencing analysis of its genetic structure, moving elements, the resistance mechanism of its research. Results Enterobacter cloacae B557 produces class B carbapenemase and the gene blaNDM encoding NDM is located on plasmid pB557-NDM. pB557-NDM enters the recipient bacteria EC600 by conjugation transfer and expresses the corresponding drug resistance spectrum. Plasmid pB557-NDM is an Inc A / C2 plasmid of size 141.65 kb with Gen Bank accession number KX786648. The plasmid has two extrinsic insertions, namely the blaCMDM-6 resistant region formed by the ISEcp1-blaCMY transposable element and the blaNDM-1 resistant region comprised of ΔTn1696-In46-rmt C-ISKpn14-ΔTn125. Conclusion Plasmid pB557-NDM mediates multidrug resistance in E. cloaci B557, and blaNDM is located in transposon ΔTn125.