title: Novel Mutation Sites in the Development of Vancomycin- Intermediate Resistance inStaphylococcus aureus.
abstract: Increased use of vancomycin has led to the emergence of vancomycin-intermediateStaphylococcus aureus(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 vancomycinin vitrofor 60 days. MICs were determined by the agar dilution andE-test methods. Vancomycin was then removed to assess the stability of VISA strains and mutations. Following 60 days of vancomycin treatmentin vitro, 29/42 VISA strains were generated. The complete sequences ofrpoB, vraS, graR, graS, walK, andwalRwere compared with those in the parental strains. Seven missense mutations including four novel mutations (L466S inrpoB, R232K ingraS, I594M inwalk, and A111T inwalR) 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 thatrpoB, graS, walk, andwalRare more important thanvraSandgraRin VISA development.
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China.
authors.forename: Yubing
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China.
authors.forename: Libo
authors.initials: L
authors.lastname: Jiang
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Han
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China.
authors.forename: Xiangming
authors.initials: X
authors.lastname: Xie
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Jin
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: He
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China; Center for Statistical Genetics, Pennsylvania State UniversityHershey, PA, USA.
authors.forename: Rongling
authors.initials: R
authors.lastname: Wu
keywords: Staphylococcus aureus; drug-resistance; jonckheere-terpstra trend test; mutations; vancomycin