In vitro antimicrobial activity of imipenem in combination with vancomycin or teicoplanin against Staphylococcus aureus and Staphylococcus epidermidis.

The interaction between imipenem and two glycopeptides against staphylococci was examined for potential synergy. Imipenem in combination with vancomycin or teicoplanin exerted a synergistic or additive effect against a majority of Staphylococcus aureus and Staphylococcus epidermidis isolates tested by the checkerboard method. Synergistic inhibitory effects were frequently accompanied by synergistic bactericidal effects. For a proportion of bacterial isolates of both species, the demonstration of synergy by the checkerboard method was confirmed by time-kill studies using antibiotic combinations at the MICs or at achievable serum antibiotic levels. Only with a single isolate of Staphylococcus epidermidis was antagonism with either antibiotic combination recorded.