Kill kinetics and regrowth pattern of bacteria exposed to antibiotic concentrations simulating those observed in vivo.

Antibiotic concentrations observed in vivo were simulated in an in vitro two compartment model with a dialyser interconnection. Kill kinetics and regrowth pattern of bacteria were investigated under these fluctuating antibiotic concentrations. There were large differences in the rate of reduction of viable organisms by various antibiotics not reflected in small differences in initial MIC values. Data suggested that the area under the concentration curve might be of importance in determining the antimicrobial activity of substances rather than the initial concentration. The inclusion of pharmacokinetic parameters in antimicrobial susceptibility testing might add a new dimension to the appreciation of the activity of antimicrobial substances.