急诊重症监护病房耐碳青霉烯类肠杆菌科细菌的分子流行特征

Molecular epidemiology of carbapenem-resistant Enterobacteriaceae in an emergency intensive care unit

目的了解急诊重症监护病房(EICU)耐碳青霉烯类肠杆菌科细菌(CRE)的分子流行特征,为临床抗感染及合理用药提供依据。方法收集2011年12月—2014年10月入住EICU患者送检标本且经VITEK2鉴定为CRE,进行改良Hodge试验、金属酶和超广谱β内酰胺酶(ESBL)表型确证试验,聚合酶链反应(PCR)检测CRE菌株携带的耐药基因,通过肠杆菌基因间重复序列-PCR(ERIC-PCR)技术进行同源性分析,明确EICU是否存在克隆株的流行。结果 1EICU分离的CRE菌株高产碳青霉烯酶和ESBL,改良Hodge试验、金属酶和ESBL表型确证试验阳性率分别为96%、13%和52%,其中以KPC-2、TEM和SHV为主,各自携带率分别为86%、86%和96%。2从2株耐碳青霉烯类的大肠埃希菌和1株阴沟肠杆菌中分离出较少见的B类碳青霉烯酶耐药基因NDM-1。3ERIC-PCR分析表明EICU分离的CRE菌株中48株肺炎克雷伯菌的电泳图谱相同,3株大肠埃希菌和1株阴沟肠杆菌的电泳条带各不相同。结论 EICU中分离的CRE高产碳青霉烯酶和ESBL,且为同一克隆菌株播散,表明该院耐药形势严峻,积极的预防和抗感染势在必行。

Objective To characterize the molecular epidemiology of carbapenem-resistant Enterobacteriaceae （CRE） in an emergency intensive care unit（EICU） for rational antimicrobial therapy. Methods Specimens were collected between December 2011 and October 2014 from patients treated in the EICU to isolate and identify CRE strains by an automated analyzer （VITEK 2）. Modified Hodge test （MHT）, metallo-beta-lactamases （MBL） and extended spectrum β-lactamases （ESBLs） phenotype confirmation test, and polymerase chain reaction were carried out to characterize the strains. The homology of strains was analyzed by enterobacterial repetitive intergenic consensus （ERIC）-PCR. Results A total of 52 strains of CRE were identified. Carbapememase and ESBLs were highly prevalent in the CRE isolated from this EICU. Overall, 96%, 13% and 52% of the strains were positive for MHT, MBL and ESBLs confirmation test, respectively. PCR analysis showed that majority of the enzymes were KPC2, TEM, and SHV, a prevalence of 86%, 86% and 96%, respectively. NDM-1 gene was identified from two strains of E. coli and one strain of E. cloacae. ERIC-PCR demonstrated that 48 of the carbapenem-resistant K. pneumoniae isolates belonged to the same genotype. Conclusions Carbapememase and ESBLs are highly prevalent in the CRE isolated from this EICU. Most of the CRE strains are from the same clone, suggesting the possibility of an epidemic. It is necessary to put aggressive infection control measures in place to control the spread of these bacteria.