title: Phenotypic and genomic comparisons of highly vancomycin-resistant Staphylococcus aureus strains developed from multiple clinical MRSA strains by in vitro mutagenesis.
abstract: The development of vancomycin (VCM) resistance in Staphylococcus aureus threatens global health. Studies of the VCM-resistance mechanism and alternative therapeutic strategies are urgently needed. We mutagenized S. aureus laboratory strains and methicillin-resistant S. aureus (MRSA) with ethyl methanesulfonate, and isolated mutants that exhibited high resistance to VCM (minimum inhibitory concentration = 32 μg/ml). These VCM-resistant strains were sensitive to linezolid and rifampicin, and partly to arbekacin and daptomycin. Beta-lactams had synergistic effects with VCM against these mutants. VCM-resistant strains exhibited a 2-fold increase in the cell wall thickness. Several genes were commonly mutated among the highly VCM-resistant mutants. These findings suggest that MRSA has a potential to develop high VCM resistance with cell wall thickening by the accumulation of mutations.
authors.affiliation: Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishii
authors.affiliation: Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Tabuchi
authors.affiliation: Department of Bacteriology, Faculty of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Matsuo
authors.affiliation: Department of Infection Control and Prevention, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Tatsuno
authors.affiliation: Department of Infection Control and Prevention, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Medical Technology, School of Health Sciences, Tokyo University of Technology, Tokyo, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Okazaki
authors.affiliation: Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hamamoto
authors.affiliation: Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Chikara
authors.initials: C
authors.lastname: Kaito
authors.affiliation: Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Aoyagi
authors.affiliation: Department of Bacteriology, Faculty of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramatsu
authors.affiliation: Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kaku
authors.affiliation: Department of Infection Control and Prevention, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Kyoji
authors.initials: K
authors.lastname: Moriya
authors.affiliation: Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Sekimizu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002473:Cell Wall / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005020:Ethyl Methanesulfonate / Q000633:toxicity; D023281:Genomics; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D016296:Mutagenesis; D009153:Mutagens / Q000633:toxicity; D010641:Phenotype; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology / Q000473:pathology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D009153:Mutagens; D014640:Vancomycin; D005020:Ethyl Methanesulfonate