Genetic Characterization of vanG, a Novel Vancomycin Resistance Locus of Enterococcus faecalis

Enterococcus faecalis strain WCH9 displays a moderate level of resistance to vancomycin (MIC = 16 μg/ml) and full susceptibility to teicoplanin but is negative by PCR analysis using primers specific for all known enterococcal vancomycin resistance genotypes (vanA, vanB, vanC, vanD, and vanE). We have isolated and sequenced a novel putative vancomycin resistance locus (designated vanG), which contains seven open reading frames, from this strain. These are organized differently from those of all the other enterococcal van loci, and, furthermore, the individual vanG gene products exhibit less than 50% amino acid sequence identity to other van gene products.

粪肠球菌（Enterococcus faecalis）菌株WCH9对万古霉素（vancomycin）呈现中度耐药性，最低抑菌浓度（MIC）为16 μg/ml，且对替考拉宁（teicoplanin）完全敏感；但采用针对所有已知肠球菌万古霉素耐药基因型（vanA、vanB、vanC、vanD及vanE）的特异性引物进行聚合酶链式反应（PCR）分析时，该菌株结果呈阴性。我们从该菌株中分离并测序得到一个新型假定的万古霉素耐药基因座（命名为vanG），该基因座包含7个开放阅读框。这些开放阅读框的排布方式与所有其他肠球菌van基因座均不相同，且进一步而言，vanG各基因的编码产物与其他van基因编码产物的氨基酸序列一致性均低于50%。