住院患儿临床分离碳青霉烯类耐药肺炎克雷伯菌分子流行病学特征

Molecular epidemiology of the carbapenem-resistant Klebsiella pneumoniae strains isolated from pediatric patients

目的研究住院儿童患者中碳青霉烯类耐药肺炎克雷伯菌(CRKP)流行特征及耐药机制,为抗菌药物合理应用和医院感染防控提供科学依据。方法收集2014年1月-2016年12月16株来自儿科病房[普通儿科和新生儿重症监护病区(NICU)]的CRKP,采用自动化仪器法或纸片扩散法(K-B法)检测其对常用抗菌药物耐药性,乙二胺四乙酸(EDTA)协同试验和3'-氨基苯硼酸(APB)协同试验进行碳青霉烯酶表型分析,PCR扩增及DNA测序进行碳青霉烯酶基因型确证,脉冲场凝胶电泳(PFGE)检测菌株间基因相关性。结果 16株CRKP菌株对多黏菌素E、阿米卡星、喹诺酮类等抗菌药物均敏感,对β内酰胺类抗菌药物高度耐药,对头孢菌素耐药率均为100%,对亚胺培南、美罗培南、厄他培南的耐药率均是100%。PCR及DNA测序显示16株CRKP中1株产blaNDM-16,1株同时产blaNDM-16和blaNDM-5,2株产blaIPM-34,2株产blaIPM-4,其他10株未检出碳青霉烯酶相关基因,仅产Amp C酶DHA-1或超广谱β内酰胺酶(ESBL)CTX-M-65、CTX-M-15、CTX-M-3;PFGE分型显示,其中部分菌株具有相关性。结论该院儿科病房的CRKP主要是产ESBL酶CTX-M-65、CTX-M-15、CTXM-3和Amp C酶DHA-1,仅部分产B类金属酶NDM-16和NDM-5。

Objective To characterize the epidemiology and resistance mechanism of the carbapenem-resistant Klebisella pneumoniae(CRKP)strains isolated from pediatric patients for rational use of antibiotics and effective hospital infection control.Methods A total of 16 CRKP strains were isolated from pediatric patients in the First People’s Hospital of Yinchuan from January 2014 to December 2016.Antimicrobial susceptibility testing was conducted by automated systems or Kirby-Bauer method.The phenotypes of carbapenemase-producing strains were identifed by 3'-aminophenylboronic acid(APB)or EDTA synergy test.Resistance determinants were detected by PCR and DNA sequencing.Conjugation experiment was used to determine whether the carbapenemase genes were located in mobile plasmids.Clonal relatedness was analyzed by pulsed field gel electrophoresis(PFGE).Results All the 16 CRKP strains were susceptible to colistin,amikacin,and ciprofloxacin,but all resistant to cephalosporins and carbapenems.PCR and DNA sequencing analysis confirmed that one isolate carried blaNDM-16,and one isolate carried blaNDM-16 and blaNDM-5,2 isolates carried blaIPM-34,2 isolates carried blaIPM-4 gene.Carbapenemase-related genes were not found in the remaining 10 strains.Only AmpC enzyme and ESBLs blaCXT-M are produced.The PFGE results showed that some of these strains are related.Conclusions CTX-M and AmpC DHA-1 production are the mechanisms of carbapenem resistance in the K.pneumoniae strains isolated from the pediatric patients in this hospital.NDM-16 and NDM-5 producing K.pneumoniae is emerging in this hospital.