Synergism between cefotaxime and fosfomycin in the therapy of methicillin and gentamicin resistant Staphylococcus aureus infection in rabbits.

An experimental model of infected subcutaneous fibrin clots in rabbits was used to study the synergism between cefotaxime and fosfomycin in infection with methicillin and gentamicin resistant Staphylococcus aureus (MGRSA), and to determine the efficacy of a simplified schedule of administration. The bactericidal activity of cefotaxime and fosfomycin against MGRSA was investigated giving the drugs in one full or two divided doses either alone or in combination. The pharmacokinetics of the drugs were correlated with the antibacterial efficacy obtained over 12 hours of treatment. The results confirmed that the combination of cefotaxime and fosfomycin is highly synergistic in experimental MGRSA infection. Higher bactericidal activity was obtained with a regimen of 6-hourly drug administration which resulted in persistent levels of both drugs in serum as well as at the site of infection.