title: In vitro activity of lauric acid or myristylamine in combination with six antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA).
abstract: The objective of this study was to investigate the in vitro activities of lauric acid and myristylamine in combination with six antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA). The combination effect of lipids and antimicrobial agents was evaluated by the checkerboard method to obtain a fractional inhibitory concentration (FIC) index. The effects of lauric acid + gentamicin (GM) and lauric acid + imipenem (IPM) combinations were synergistic against the clinical isolates in 12 combinations. An antagonistic FIC index was observed only with the myristylamine + GM combination. We investigated in detail the antimicrobial activity for two combinations that showed a synergistic effect. The cytotoxicity of lauric acid was not enhanced by the addition of GM and IPM. In time-kill studies, lauric acid + GM and lauric acid + IPM combinations at one-eighth of the minimum inhibitory concentration produced a bacteriostatic effect.
authors.affiliation: Department of Hospital Pharmacy, Nagasaki University Hospital of Medicine and Dentistry, Japan. kitappy@net2.nagasaki-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kitahara
authors.forename: Yuko
authors.initials: Y
authors.lastname: Aoyama
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Hirakata
authors.forename: Shimeru
authors.initials: S
authors.lastname: Kamihira
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kohno
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ichikawa
authors.forename: Mikiro
authors.initials: M
authors.lastname: Nakashima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sasaki
authors.forename: Shun
authors.initials: S
authors.lastname: Higuchi
mesh_terms: D000588:Amines / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002460:Cell Line; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D006801:Humans; D007850:Lauric Acids / Q000494:pharmacology*; D016106:Methicillin Resistance; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D018675:Toxicity Tests
chemical_list: D000588:Amines; D000900:Anti-Bacterial Agents; D007850:Lauric Acids; C030358:lauric acid; C020514:N-tetradecylamine