肠道定植耐碳青霉烯类肠杆菌目细菌的主动筛查及分子流行病学

Active surveillance and molecular epidemiological study of intestinal colonization of carbapenem-resistant Enterobacterales

目的筛查住院患者肠道定植耐碳青霉烯类肠杆菌目细菌(carbapenem-resistant Enterobacterales,CRE)的检出率,并分析CRE菌株分子的流行病学特征。方法本研究为前瞻性研究。采集2019年3月至12月安徽医科大学第二附属医院外科重症监护病房、内科重症监护病房和血液内科(移植病房)213例住院患者的粪便、直肠拭子或肛周拭子标本,应用含碳青霉烯类药物的麦康凯平板法筛查CRE菌株,并进行细菌鉴定、药物敏感试验,选取重点菌株进行全基因组测序,并分析其多位点序列分型、荚膜血清型、耐药基因、毒力基因和质粒携带特征。以菌株KPN FJ723042序列作为参考,对所有菌株序列进行单核苷酸多态性分析。结果共检出CRE菌株23株,检出率为10.8%(23/213);其中耐碳青霉烯类肺炎克雷伯菌(carbapenem-resistant Klebsiella pneumoniae,CRKP)15株(65.2%),大肠埃希菌和阴沟肠杆菌各3株(13.0%),弗氏柠檬酸杆菌2株(8.7%)。单核苷酸多态性聚类分析表明,15株CRKP有2组主要克隆型,均在外科重症监护病房内流行。15株CRKP均属于ST11-K64型,均携带β-内酰胺类耐药基因肺炎克雷伯菌碳青霉烯酶2型(β-lactamase Klebsiella pneumoniae carbapenemase 2,blaKPC-2)基因;12株CRKP携带毒力基因黏液表型调控基因2型(regulator of mucoid phenotype gene A2,rmpA2)、iucABCD。结论住院患者中肠道定植CRE的检出率较高,以ST11-K64型CRKP为主,CRKP菌株兼具多重耐药性和毒力特征,有医院传播风险。

Objective To investigate the detection rate of intestinal colonization of carbapenem-resistant Enterobacterales(CRE)in inpatients,and to analyze the molecular epidemiological characteristics of CRE strains.Methods This was a prospective study.Stool,rectal swab or perianal swab specimens of 213 inpatients in the surgical intensive care unit(SICU),medical intensive care unit(MICU)and the department of hematology(transplantation ward)in The Second Hospital of Anhui Medical University were collected from March to December,2019.MacConkey plate containing carbapenems was used to screen CRE strains,and bacteria identification and drug susceptibility test were conducted.Key strains were selected for whole genome sequencing(WGS).Besides,multilocus sequence typing,capsular serotype,drug resistance gene,virulence gene and plasmid carrying characteristics of these strains were analyzed.Using KPN FJ723042 sequence as a reference,the single-nucleotide polymorphism(SNP)of all strains was analyzed.Results Twenty-three CRE strains were detected,with a detection rate of 10.8%(23/213),which included 15(65.2%)carbapenem-resistant Klebsiella pneumoniae(CRKP)isolates,three(13.0%)Escherichia coli strains,three(13.0%)Enterobacter cloacae strains and two(8.7%)Citrobacter freundii strains.SNP cluster analysis showed that the 15 CRKP strains had two main clonotypes,which were both predominant in SICU.Fifteen strains of CRKP were type ST11-K64.All these strains carriedβ-lactamase Klebsiella pneumoniae carbapenemase 2(blaKPC-2),and 12 strains carried regulator of mucoid phenotype gene A2(rmpA2)and iucABCD.Conclusions The detection rate of intestinal colonization of CRE in inpatients is high,and most strains are CRKP of type ST11-K64.These CRKP strains have both multidrug resistance and virulence characteristics,which are risks for hospital transmission.