重庆某院耐万古霉素屎肠球菌的分子流行病学研究和感染危险因素分析

Molecular epidemiology and infection risk factors for vancomycin-resistant Enterococcus faecium from a hospital in Chongqing region

目的探究耐万古霉素屎肠球菌(vancomycin-resistant Enterococcus faecium,VREfm)的毒力基因、转座子分型和危险因素。方法收集本院2012年1月至2014年2月经微量肉汤稀释法验证的耐万古霉素屎肠球菌18株,采用梅里埃VITEK2对13种抗生素进行MIC检测;通过多重PCR检测Van耐药基因和7种毒力基因,重叠PCR分析耐药转座子Tn1546结构,多位点序列分型(multilocus sequence typing,MLST)方法确定菌株序列型别,并采用回顾性病例对照分析进行危险因素调查。结果 18株VREfm基因型和表型均符合Van A型;所有菌株对青霉素、氨苄西林、环丙沙星等表现耐药,对替加环素、利奈唑胺和奎奴普丁-达福普汀表现敏感;毒力基因acm、esp、hyl检测率分别为94.4%、88.9%、83.3%;耐药转座子结构共检测到4种类型;MLST结果显示共有5种ST型别,均属于克隆复合体CC17。毒力基因esp、转院患者、尿路感染和万古霉素使用是VREfm感染的独立危险因素。结论收集到的18株VREfm均为多重耐药菌,且均属于克隆复合体CC17。毒力基因esp检出率较高,且与万古霉素耐药显著相关。

Objective To determine the virulence genes,resistance transposon types and infection risk factors of Vancomycin-resistant Enterococcus faecium（ VREfm） isolates. Methods Eighteen VREfm isolates were collected in our hospital from January 2012 to February 2014,and all isolates were validated by broth dilution susceptibility testing. The minimum inhibitory concentrations（ MIC） of the 13 antimicrobial agents were tested by using VITEK 2 compact. The Van resistance genes and virulence genes were detected by multiplex PCR. The resistant transposon Tn1546 were analyzed by overlapping PCR,and the sequence type was identified by multilocus sequence typing（ MLST）. A case-control study was conducted to investigate the risk factors for VREfm infection. Results All 18 strains of VREfm showed the genotype and phenotype of Van A,had a 100% rate of resistance to penicillin,ampicillin,ciprofloxacin,and a 100% rate of sensitivity to tigecycline,linezolid and quinupristin/dalfopristin. PCR analysis revealed that the presences of virulence genes were 94. 4% in acm,88. 9% in esp,and 83. 3% in hyl in the VREfm isolates. There were 4 different transposon types of Tn1546 identified. MLST analysis identified 5 different sequence types,and all belonged to clonal complex 17（ CC17）. The presence of virulence genes esp,referred patients,urinary tract infection,and prior use of vancomycin were independent risk factors for the acquisition of VREfm. Conclusion All 18 strains of VREfm are multi-drug resistant,and belong to CC17. The high presence of virulence gene esp is significantly associated with VREfm.