TABLE 3

Parameter estimates for the in vitro PK/PD model

ParameterExplanationValue for strain:
ATCC 19606A. baumannii 1845A. baumannii 2092
kgrowth (h−1)Rate constant of bacterial net growth0.2501.010.640
Bmax (log10CFU/ml)Bacterial count in the stationary phase8.568.028.03
Emax_CST (h−1)Maximum achievable kill rate constant by colistin7.210.9984.66
EC50_CST (mg/liter)Colistin concentration that results in 50% of Emax0.07150.3740.730
Emax_MEM (h−1)Maximum achievable kill rate constant by meropenem1.110.9470.095
EC50_MEM (mg/liter)Meropenem concentration that results in 50% of Emax15.514.813.5
γCSTHill factor for colistin1.271.051.55
γMEMHill factor for meropenem0.3060.7737.30
fMaximal adaptation factor2903.609.54
kRate of adaptation1.060.1560.444
IntParameter describing drug interaction0.1900.01180.0117
fval (%)Residual error fraction5.993.772.23