title: Efficacy of vancomycin-beta-lactam combinations against heterogeneously vancomycin-resistant Staphylococcus aureus (hetero-VRSA).
abstract: There have been conflicting data about the interactions between vancomycin and beta-lactam agents against Staphylococcus aureus strains with heterogeneous resistance to vancomycin. We evaluated the efficacy of these combinations against Mu 3 and heterogeneously vancomycin-resistant S. aureus (hetero-VRSA) strains which were isolated from Korean patients using a population analysis method. Antagonistic effects were observed when less than 1 g/mL of beta-lactam antibiotics was combined with vancomycin, whereas synergistic effects were noticed with more than 4 microgram/mL of beta-lactam antibiotics. The antagonistic effects at low concentrations of beta-lactams were most prominent at 2 microgram/mL of vancomycin, which were the vancomycin MICs of tested hetero-VRSA strains. This study showed the variable effects of vancomycin- beta-lactam combinations depending on the concentrations of beta-lactam antibiotics and this property could be used to develop screening methods for hetero-VRSA strains.
authors.affiliation: Department of Internal Medicine, Chungnam National University Hospital, Daejeon, Korea.
authors.forename: Yeon Sook
authors.initials: YS
authors.lastname: Kim
authors.forename: Sungmin
authors.initials: S
authors.lastname: Kiem
authors.forename: Hwan-Jung
authors.initials: HJ
authors.lastname: Yun
authors.forename: Sook In
authors.initials: SI
authors.lastname: Jung
authors.forename: Won Sup
authors.initials: WS
authors.lastname: Oh
authors.forename: Shin-Woo
authors.initials: SW
authors.lastname: Kim
authors.forename: Kyong Ran
authors.initials: KR
authors.lastname: Peck
authors.forename: Nam Yong
authors.initials: NY
authors.lastname: Lee
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Song
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002439:Cefotaxime / Q000494:pharmacology; D004357:Drug Synergism; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D002439:Cefotaxime; D010068:Oxacillin