Wang Yubing, Li Xiaoli, Jiang Libo, Han Wentao, Xie Xiangming, Jin Yi, He Xiaoqing, Wu Rongling
College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China.
College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China.
Front Microbiol. 2017 Jan 10;7:2163. doi: 10.3389/fmicb.2016.02163. eCollection 2016.
Increased use of vancomycin has led to the emergence of vancomycin-intermediate (VISA). To investigate the mechanism of VISA development, 39 methicillin-susceptible strains and 3 MRSA strains were treated with vancomycin to induce non-susceptibility, and mutations in six genes were analyzed. All the strains were treated with vancomycin for 60 days. MICs were determined by the agar dilution and -test methods. Vancomycin was then removed to assess the stability of VISA strains and mutations. Following 60 days of vancomycin treatment , 29/42 VISA strains were generated. The complete sequences of , and were compared with those in the parental strains. Seven missense mutations including four novel mutations (L466S in , R232K in , I594M in , and A111T in ) were detected frequently in strains with vancomycin MIC ≥ 12 μg/mL. Jonckheere-Terpstra trend test indicated these mutations might play an important role during VISA evolution. After the vancomycin treatment, strains were passaged to vancomycin-free medium for another 60 days, and the MICs of all strains decreased. Our results suggest that , and are more important than and in VISA development.
万古霉素使用的增加导致了万古霉素中介金黄色葡萄球菌（VISA）的出现。为了研究VISA产生的机制，用万古霉素处理39株甲氧西林敏感菌株和3株耐甲氧西林金黄色葡萄球菌（MRSA）菌株以诱导其产生耐药性，并分析6个基因的突变情况。所有菌株均用万古霉素处理60天。通过琼脂稀释法和E试验方法测定最低抑菌浓度（MIC）。然后去除万古霉素以评估VISA菌株的稳定性和突变情况。经过60天的万古霉素处理后，产生了29/42株VISA菌株。将这些菌株的、和的完整序列与亲本菌株的进行比较。在万古霉素MIC≥12μg/mL的菌株中频繁检测到7个错义突变，包括4个新突变（中的L466S、中的R232K、中的I594M和中的A111T）。Jonckheere-Terpstra趋势检验表明这些突变可能在VISA进化过程中起重要作用。万古霉素处理后，将菌株转接至不含万古霉素的培养基中再培养60天，所有菌株的MIC均下降。我们的结果表明，在VISA产生过程中，、和比和更重要。
