重症监护病房耐碳青霉烯类肺炎克雷伯菌分子流行病学研究

Molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae in intensive care unit

摘要:

目的 分析重症监护病房(ICU)临床来源耐碳青霉烯肺炎克雷伯菌(CRKP)的分子特征及流行情况, 为感染控制及药物治疗提供实验室数据。 方法 收集2018年7月-2020年7月某院ICU分离的51株CRKP, 采用微量肉汤稀释法测定最低抑菌浓度, 多位点序列分型和脉冲场凝胶电泳分析菌株同源性, 检测菌株耐药和毒力基因, 接合试验验证质粒的转移性。 结果 药敏试验显示, CRKP对头孢他啶/阿维巴坦全部敏感, 对替加环素耐药率最低(3.9%), 其次是阿米卡星(49.0%)、多粘菌素(64.7%), 对亚胺培南(96.1%)、美罗培南(98.0%)、左氧氟沙星(98.0%)和头孢他啶(100.0%)均高度耐药。51株CRKP中, mCIM试验阳性菌株49株(96.1%), eCIM试验阳性菌株1株(2.0%)。碳青霉烯酶基因bla_KPC-2阳性菌株占96.1%。所有分离株中, 高黏液表型阳性4株(7.8%), 毒力基因阳性情况分别为: uge 100.0%, mrkD 94.1%, kpn 94.1%, fim-H 72.5%, aero 2.0%, rmpA 2.0%。ST11 CRKP在ICU中占98.0%(50/51), ST1373占2.0%(1/50)。检出1株ST1373的高毒力肺炎克雷伯菌。携带bla_KPC-2基因菌株的接合试验成功率为12.2%。 结论 ICU存在产KPC-2的ST11 CRKP单克隆传播, 同时携带一定的毒力基因。携带bla_KPC-2基因的质粒可通过接合水平传播。头孢他啶/阿维巴坦对CRKP有较高的敏感性, 可供临床治疗选择使用。

Abstract:

Objective To analyze the molecular characteristics and prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolated from the intensive care unit (ICU), and provide laboratory data for infection control and antimicrobial treatment. Methods 51 CRKP strains isolated from ICU of a hospital from July 2018 to July 2020 were collected, minimum inhibitory concentration (MIC) was determined by broth microdilution method, homology of strains was analyzed by multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE), resis-tance and virulence genes of strains were detected, transferability of plasmid was verified with conjugation testing. Results Antimicrobial susceptibility testing showed that CRKP strains were all susceptible to ceftazidime/avibactam, resistance rate to tegacyclin was the lowest (3.9%), followed by amikacin (49.0%) and polymyxin (64.7%), while strains were all highly resistant to imipenem (96.1%), meropenem (98.0%), levofloxacin (98.0%) and ceftazidime (100.0%). Among 51 CRKP strains, 49 strains (96.1%) were positive in mCIM testing, 1 strain (2.0%) was positive in eCIM testing. Carbapenemase gene bla_KPC-2 positive strains accounted for 96.1%. Among all isolates, 4 strains (7.8%) exhibited the hypermucoviscous phenotype, positive rates of virulence genes were uge (100.00%), mrkD (94.1%), kpn (94.1%), fim-H (72.5%), aero (2.0%), and rmpA (2.0%). ST11 and ST1373 CRKP accounted for 98.0% (50/51) and 2.0% (1/50) respectively among ICU strains. One highly virulent Klebsiella pneumoniae strain ST1373 was isolated. The success rate of conjugation testing of bla_KPC-2-harboring strains was 12.2%. Conclusion There is a monoclonal transmission of ST11 CRKP that produces KPC-2 in ICU, and it carries certain virulence genes. The plasmid of bla_KPC-2-harboring gene can be transmitted horizontally through conjugation. Ceftazidime/avibactam has high susceptibility to CRKP and can be used in clinical treatment.