The post-antibiotic sub-MIC effect in vitro and in vivo.

The post-antibiotic effect (PAE) has been recognized as a pharmacodynamic parameter which may influence optimal dosage intervals. During the post-antibiotic phase, various bacteria have been shown to be very sensitive to a repeated exposure to the same antibiotic. A long period of growth suppression may be obtained when a low concentration (< or = 0.3 x MIC) is added to bacteria previously exposed to a supra-inhibitory concentration. This phenomenon has been named the post-antibiotic sub-MIC effect (PA SME). Since a period with sub-inhibitory concentrations will often exist between the doses when intermittent dosing of antibiotics is used, the PA SME probably reflects the in-vivo situation more closely than the PAE. The published literature on the PA SME is reviewed and its possible role in antibiotic dosing discussed.