The postantibiotic effect of fusidic acid against gram-positive bacteria.

The in-vitro postantibiotic effect (PAE) of fusidic acid was tested for six strains of Staphylococcus aureus and four strains of Streptococcus pyogenes. The maximum PAE that could be achieved was more than 3 h, but at concentrations of antibiotic attainable in humans, the PAE was less than 2 h. Additional experiments were performed in albumin, to examine the effect of the strong protein binding of fusidic acid on the MIC and PAE. MICs were increased, but at the same multiple of the MIC, PAEs were similar to those performed in Mueller-Hinton broth.