ST571型产NDM-1肺炎克雷伯菌检出及分子流行病学研究

Isolation and molecular epidemiology of ST571 NDM-1 producing Klebsiella pneumoniae

目的探讨产新德里金属-β-内酰胺酶1(NDM-1)肺炎克雷伯菌检出的分子流行病学意义。方法实验菌株为从临床标本中分离到的1株耐碳青霉烯类肺炎克雷伯菌。采用VITEK-2 Compact全自动微生物分析系统进行鉴定及药敏试验,PCR及测序方法检测NDM-1等碳青霉烯酶基因的表达,并对菌株进行质粒转移接合试验及多位点序列分型(MLST)。经检索Pub Med收集其他地区产NDM-1肺炎克雷伯菌的MLST数据,采用e BURST V3软件及Tree drawing软件进行分析。结果该菌株对包括碳青霉烯类在内的多种抗生素均高度耐药,携带NDM-1基因,MLST为ST571含有该基因的质粒通过接合方式成功转移到受体菌。共收集源自28个国家的238株产NDM-1肺炎克雷伯菌的MLST信息,包含41个ST型,CC258(clone complex)为主要流行株。结论我国首次检出ST571型产NDM-1肺炎克雷伯菌,耐药基因可能通过质粒进行传播。产NDM-1肺炎克雷伯菌的分子分型呈多样化,以CC258流行最广,本实验菌株与该克隆复合体菌株的亲缘关系甚远。

Objective To investigate the molecular epidemiological significance of isolating a New Delhi metallo-β-lactamase-1（ NDM-1） producing Klebsiella pneumoniae（ K. pneumoniae） strain. Methods The strain was a carbapenems resistant K. pneumoniae strain isolated from clinical samples. VITEK-2 Compact instrument was used for identification and antibiotic susceptibility test. Expressions of NDM-1 genes and carbapenemases genes were detected by the PCR. The transfer plasmid conjugation experiment and multilocus sequence typing（ MLST） were performed. MLST data of NDM-1 producing K. pneumoniae from other areas was collected from Pub Med and analyzed by e BURST V3 software and Tree drawing software. Results The isolated strain was highly resistant to many antibiotics including carbpenems and carried the NDM-1 gene. Plasmids that contained the NDM-1 gene were successfully transferred to recipient bacteria by conjugation and the MLST of K. pneumoniae strain was ST571. The MLST data of 283 NDM-1 producing K. pneumoniae strains from 28 countries were collected, including 42 ST strains. The major epidemic strain was CC258 strain（ clone complex）. Conclusion The ST571 NDM-1 producing K. pneumoniae strain is isolated in China for the first time. The drug resistant gene may be transmitted by plasmids.The molecular typing of NDM-1 producing K. pneumoniae is diverse. CC258 strain is the most epidemic strain. The isolated strain is genetically far from cloned CC258 strain.