ST2928新型耐碳青霉烯类高毒力肺炎克雷伯菌引起的重症肺炎1例

目的 分析耐碳青霉烯类高毒力肺炎克雷伯菌（CR-HvKP）的分子特征和毒力，以加强临床工作者对该菌的认识。方法 对1株分离自重症肺炎患者呼吸道标本的CR-HvKP进行药敏试验，并研究其对碳青霉烯类的耐药机制，通过拉丝试验、毒力基因检测、毒力相关荚膜抗原基因检测、多位点序列分型、大蜡螟感染模型试验和患者临床表现分析该菌的分子及毒力特征。结果 CR-HvKP引起了患者严重的肺部感染，予以纤维支气管镜检查取肺泡灌洗液标本培养分离病原菌，根据其药敏结果及时更改抗菌药物后患者病情得到控制。该菌为多重耐药株，表达IMP-4型碳青霉烯酶，拉丝试验阴性，为ST2928型，prmpA₂毒力基因阳性，K54荚膜抗原基因阳性，在大蜡螟模型试验中表现出较高的体外毒力。结论 此次分离的ST2928型、K54荚膜抗原基因阳性并且产IMP-4型碳青霉烯酶的CR-HvKP系首次报告，CR-HvKP因其高耐药性和高毒力的结合可引起较为复杂和严重的感染，其分子特征呈多样性。

One case of severe pneumonia caused by a newly emerged ST2928 carba-penem-resistant hypervirulent Klebsiella pneumoniae

Objective To analyze the molecular characteristics and virulence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-HvKP), strengthen the clinical staff''s understanding on this bacteria. Methods One strain of CR-HvKP isolated from respiratory tract specimen of a patient with severe pneumonia was performed antimicrobial susceptibility testing, resistance mechanism to carbapenems was studied. The molecular and virulence characteristics of the strain were analyzed through string test, virulence gene detection, virulence-related capsular antigen gene detection, multilocus sequence typing, Galleria mellonella infection model, and clinical manifestation of patient. Results CR-HvKP caused severe pneumonia in patient, patient received bronchoscopy, bronchoalveolar lavage fluid (BALF) specimen was taken for pathogenic culture and isolation, patient''s condition was under control after adjusting antimicrobial use according antimicrobial susceptibility testing result. The strain was multidrug-resistant, expressed IMP-4 carbapenemase, negative for string test, ST2928 type, positive for prmpA₂ virulence gene, positive for K54 capsular antigen gene, and in vitro high virulence in Galleria mellonella model test. Conclusion The isolated CR-HvKP strain with ST2928, positive K54 capsular antigen gene and producing IMP-4 carbapenemase is reported for the first time, CR-HvKP can cause more complicated and severe infection due to its combination of high drug resistance and high virulence, and its molecular characteristics are diverse.