目的：研究复旦大学附属华山医院耐碳青霉烯类肺炎克雷伯菌广泛播散初期携带 blaKPC-2的完整基因结构﹐获得其播散的基因背景。方法收集2006年8月―2009年12月连续不重复的碳青霉烯类耐药肺炎克雷伯菌42株﹐进行质粒抽提、blaKPC-2筛选、多位点序列分型（MLST）；随后设计一系列 PCR 引物﹐对 blaKPC-2基因结构进行完整测序。结果 MLST 分型显示：34株属于 ST11型﹐5株属于 ST423﹐2株属于 ST65﹐1株属于 ST977。主要发现两种携带 blaKPC-2基因结构﹐A 型（8/42）：Tn1721-blaKPC-2-Tn3；B 型（34/42）：Tn1721-blaKPC-2-ΔTn3-IS26﹐且 B 型结构的两端序列存在差异。结论该组中肺炎克雷伯菌携带 blaKPC-2的基因结构存在多态性﹐Tn1721-blaKPC-2-ΔTn3-IS26样结构占优势。研究获得的携带 blaKPC-2基因结构及侧翼的完整序列﹐为进一步正确认识和理解 blaKPC-2的播散模式和机制提供了完整的基因背景。%Objective This study was designed to determine the genetic structure bearing blaKPC-2, which prevailed in the clinical K. pneumoniae isolates recovered in Huashan Hospital, Fudan University, and examine the genetic background of blaKPC-2 prevalence. Methods Forty-two consecutive and nonduplicate K. pneumoniae strains isolated during the period from August 2006 to December 2009 were included in this study. All strains were subjected to plasmid extraction, blaKPC-2 detection, and multilocus sequence typing (MLST). A series of primers were designed to analyze the genetic environment of the blaKPC-2 gene. Results MLST genotyping showed that 34 of the K. pneumoniae isolates belonged to ST11, five to ST423, two to ST65 and one to ST977. Two types of blaKPC-2-bearing genetic structures were identified: type A (8/42): Tn1721-blaKPC-2-Tn3; type B (34/42): Tn1721-blaKPC-2-ΔTn3-IS26. The flanking sequence of type B was distinct. Conclusions The genetic environment of blaKPC-2 is diverse. Tn1721-blaKPC-2-ΔTn3-IS26 is the dominant chimeric structure bearing blaKPC-2 in this set of clinical K. pneumoniae isolates. The complete genetic structure bearing blaKPC-2 and the flanking sequences characterized in this study will help to further understanding of the mode and mechanism of blaKPC-2 dissemination.
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