In vitro interactions between teicoplanin and other antibiotics against enterococci and staphylococci.

In this study we have evaluated the in vitro activity of teicoplanin, a potent anti-staphylococcal and anti-enterococcal agent, in combination with rifampicin, netilmicin, amikacin, fosfomycin and imipenem. Drug interactions were assessed using a microtitre checkerboard dilution method and a time-kill test. With rifampicin, indifference or an additive effect was the prevalent outcome with both methods. With netilmicin and amikacin synergism was seen against half of the enterococcal strains, whereas indifference was more common with staphylococcal isolates. Synergism predominated when teicoplanin was combined with fosfomycin and imipenem. Under no circumstances and with no combination of drugs were we able to detect antagonistic effects.