title: Identification of the active component that induces vancomycin resistance in MRSA.
abstract: A fraction of methicillin-resistant Staphylococcus aureus (MRSA) shows resistance to vancomycin (VCM) in the presence of β-lactam antibiotics (BIVR) at low concentrations. We hypothesized that the BIVR phenomenon might be exerted by a peptidoglycan derivative(s) generated as a consequence of β-lactam antibiotic action. To verify this hypothesis, we isolated the fraction that mimicked the effect of β-lactam antibiotics by the enzymatic treatment of the crude cell wall. The active components were purified by a combination of reverse phase chromatographies, mass spectrum and amino-acid analyses, and were identified to be a muropeptide with the following formula: N-acetyglucosamyl-N-acetylmuramyl--Ala-D-isoGln-L-Lys-(ɛ-NH-4Gly)-D-Ala-2Gly. This is the very first identification of the active component, which induces VCM resistance in MRSA. We found that the BIVR cells are highly sensitive to this compound rendering the cells resistant to VCM compared with non-BIVR MRSA.
authors.affiliation: Graduate School of Infection Control Sciences, Kitasato University, Minato-ku, Tokyo, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ikeda
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hanaki
authors.forename: Chie
authors.initials: C
authors.lastname: Yanagisawa
authors.forename: Yurika
authors.initials: Y
authors.lastname: Ikeda-Dantsuji
authors.forename: Hidehito
authors.initials: H
authors.lastname: Matsui
authors.forename: Masato
authors.initials: M
authors.lastname: Iwatsuki
authors.forename: Kazuro
authors.initials: K
authors.lastname: Shiomi
authors.forename: Taiji
authors.initials: T
authors.lastname: Nakae
authors.forename: Keisuke
authors.initials: K
authors.lastname: Sunakawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Omura
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002473:Cell Wall / Q000187:drug effects; D002853:Chromatography, Liquid; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D010457:Peptidoglycan / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D015533:Transcriptional Activation; D020713:Vancomycin Resistance; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D010457:Peptidoglycan; D047090:beta-Lactams