title: The antagonistic effects of a combination of vancomycin and minocycline in Staphylococcus aureus with heterogeneous resistance to vancomycin.
abstract: Some methicillin-resistant Staphylococcus aureus (MRSA) strains in which combinations of vancomycin (VCM) and beta-lactam antibiotics show antagonism have recently emerged, and these strains are called beta-lactam-induced VCM-resistant MRSA (BIVR). We examined whether various antibiotics exhibited an antagonistic effect with VCM when used against Mu3 and Fu10 (representative BIVR strains), using a simple agar disc method. Chloramphenicol, tetracyclines, macrolides, and lincosamides showed an antagonistic effect with VCM. We attempted to elucidate the antagonistic mechanism of a combination of VCM and minocycline (MINO) in BIVR strains. We determined the rates of autolysis, autolytic activities, and the change in morphology of Mu3 treated with a combination of VCM and MINO. We observed that Mu3 grown in a combination of VCM and MINO showed increasing rates of autolysis, and lower minimal bacteriolytic enzyme dose (MBD) values compared with Mu3 grown in VCM alone, but no cell wall thickening was observed. Taken together, these results suggest that cell wall thickening may not be essential in the increased resistance of BIVR strains. Our present data therefore suggest that these combination therapies of VCM with tetracyclines should be adopted with great care in order to prevent VCM treatment failure.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Oshiro
authors.forename: Zenzo
authors.initials: Z
authors.lastname: Nagasawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hanaki
authors.forename: Yurika
authors.initials: Y
authors.lastname: Ikeda-Dantsuji
authors.forename: Ariaki
authors.initials: A
authors.lastname: Nagayama
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001433:Bacteriolysis; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D008911:Minocycline / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification / Q000166:cytology / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D008911:Minocycline