Gu Li, Cao Bin, Liu Yingmei, Guo Ping, Song Shufan, Li Ran, Dai Huaping, Wang Chen
Beijing Institute of Respiratory Medicine, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
Diagn Microbiol Infect Dis. 2009 Jan;63(1):70-5. doi: 10.1016/j.diagmicrobio.2008.08.018.
VanB phenotype-vanA genotype vancomycin-resistant Enterococcus faecium (VREF) has never been reported in mainland China. We investigated the frequency and molecular characteristics of this strain in a Beijing tertiary hospital. Of 23 vanA genotype VREF clinical isolates, 12 (54.3%) were VanB phenotype-vanA genotype. Mutilocus sequence typing (MLST) analysis revealed that all isolates belong to a single clonal complex (CC78), which has been disseminated worldwide. Based on MLST and pulsed-field gel electrophoresis, 23 isolates were polyclonal dissemination in our hospital. Tn1546-like element structure analysis showed that of 12 VanB phenotype-vanA genotype isolates, 5 had complete deletion of vanY and vanZ accompanying insertion of IS1216V in vanX-vanY intergenic region, 5 had ISEfa4 insertion in orf2-vanR intergenic region, a new Tn1546 structure type, and 2 were identical to VanA phenotype-vanA genotype VREF. Data showed that the deletion of vanY and vanZ genes or ISEfa4 insertion in orf2-vanR intergenic region can partly explain the causes of difference between phenotype and genotype.
在中国大陆，从未有过关于具有VanB表型-vanA基因型的耐万古霉素屎肠球菌（VREF）的报道。我们在北京一家三级医院调查了该菌株的频率及分子特征。在23株vanA基因型的VREF临床分离株中，有12株（54.3%）为VanB表型-vanA基因型。多位点序列分型（MLST）分析显示，所有分离株均属于一个已在全球传播的单一克隆复合体（CC78）。基于MLST和脉冲场凝胶电泳分析，23株分离株在我院呈多克隆传播。Tn1546样元件结构分析显示，在12株VanB表型-vanA基因型分离株中，5株vanY和vanZ完全缺失，同时IS1216V插入vanX-vanY基因间隔区；5株在orf2-vanR基因间隔区有ISEfa4插入，这是一种新的Tn1546结构类型；2株与VanA表型-vanA基因型VREF相同。数据表明，vanY和vanZ基因的缺失或orf2-vanR基因间隔区的ISEfa4插入可部分解释表型与基因型差异的原因。
