Post-MIC effect of fosfomycin on Pseudomonas aeruginosa in vitro and in experimentally infected mice.

When two strains of Pseudomonas aeruginosa were subjected in vitro to decreasing fosfomycin concentrations in liquid cultures a half-life dependent delay of regrowth occurred after concentrations had fallen below the MIC (post-MIC effect). There was no post-MIC effect at the short half-lives corresponding to those normally found in mice. However, in similar experiments with surface cultures a post-MIC effect could also be demonstrated at short half-lives. No post-MIC effect, with reference to serum concentrations, could be found in mice infected with the same strains either in a septicaemia or infected thigh model.