In-vitro synergy testing of triple antibiotic combinations against Staphylococcus epidermidis isolates from patients with endocarditis.
In-vitro synergy testing was performed against ten blood or valve isolates of Staphylococcus epidermidis taken from patients with endocarditis. A three-dimensional microtitre checkerboard method was used for evaluation of vancomycin-rifampicin-gentamicin. The triple combination of vancomycin plus rifampicin plus gentamicin was found to be synergistic in 70% of the isolates. Vancomycin plus rifampicin was not synergistic. Oral agents including dicloxacillin, rifampicin, and fusidic acid were also evaluated. Four methicillin-resistant isolates were relatively resistant to dicloxacillin (MIC greater than 0.79 mg/l) but all four isolates were susceptible to fusidic acid alone and rifampicin alone. The triple combination of dicloxacillin plus fusidic acid plus rifampicin was found to be synergistic in 50% of the isolates and generally superior to any two-drug combination raising the possibility of an effective oral combination of antibiotics.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004009:Dicloxacillin / Q000494:pharmacology; D004338:Drug Combinations; D004357:Drug Synergism; D004697:Endocarditis, Bacterial / Q000382:microbiology*; D005672:Fusidic Acid / Q000494:pharmacology; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D012293:Rifampin / Q000494:pharmacology; D013212:Staphylococcus epidermidis / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D005839:Gentamicins; D005672:Fusidic Acid; D014640:Vancomycin; D004009:Dicloxacillin; D012293:Rifampin