[Pathogenic characterization of Klebsiella pneumoniae resistant to carbapenems and polymyxin].

Objective: Analysis and investigation of pathogenic characteristics of polymyxin-and carbapenem-resistant Klebsiella pneumoniae (PR-CRKP). Methods: A total of 23 PR-CRKP strains isolated from clinical specimens from the General Hospital of Southern Theater Command from March 2019 to July 2021 were retrospectively collected, Whole-genome sequencing was performed on 23 PR-CRKP strains, resistance genes were identified by comparison of the CARD and the ResFinder database, high-resolution typing of PR-CRKP strains was analyzed by core genomic multilocus sequencing (cgMLST) and single nucleotide polymorphism (SNP); polymyxin resistance genes were determined by PCR and sequencing. Results: All PR-CRKP strains were KPC-2 producing ST11 types. cgMLST results showed that the evolutionary distance between the PR-CRKP strains and Klebsiella pneumoniae in mainland China was 66.44 on average, which is more closely related than foreign strains; the 23 PR-CRKP strains were divided into 3 main subclusters based on SNP phylogenetic trees, with some aggregation among Clade 2-1 in the isolation department and date. The two-component negative regulatory gene mgrB has seven mutation types including point mutations, different insertion fragments and different insertion positions. Conclusion: The close affinity of PR-CRKP strains indicate the possibility of nosocomial clonal transmission and the need to strengthen surveillance of PR-CRKP strains to prevent epidemic transmission of PR-CRKP.目的： 分析研究耐多黏菌素和碳青霉烯类肺炎克雷伯菌（polymyxin resistant and carbapenemase-resistant Klebsiella pneumoniae，PR-CRKP）的病原特征。 方法： 回顾性收集南部战区总医院2019年3月至2021年7月临床标本分离培养出的23株PR-CRKP，通过全基因组测序，采用CARD和ResFinder数据库分析耐药基因，采用核心基因组多位点序列（core genome multilocus sequence typing，cgMLST）及单核苷酸多态性（single nucleotide polymorphism，SNP）分析菌株亲缘关系；通过PCR及测序对多黏菌素耐药基因进行分析。 结果： 23株PR-CRKP均为产KPC-2的 ST11 型，cgMLST结果显示本研究菌株与中国大陆肺炎克雷伯菌的进化距离平均为66.44，相较于国外肺炎克雷伯菌具有更密切的亲缘关系；基于SNP进化树将23株PR-CRKP分为3个主要分支，其中Clade 2-1菌株间在病区和分离时间上具有一定聚集性。双组分负调控基因mgrB存在点突变、不同插入片段、不同插入位置等为7种突变类型。 结论： PR-CRKP亲缘性较近，表明存在院内克隆传播的可能，需加强PR-CRKP菌株的监测，防止PR-CRKP在医院流行传播。.