Hill functions for two-drug combinations and the constituent individual antibiotics (<i>S. aureus</i>).

<p>Each graph shows the Hill functions for a drug combination and the constituent single drugs with drug concentrations normalized as multiples of Cidal Units (xCU). Error bars represent the standard errors for the growth/death rate at each antibiotic concentration. (a) ciprofloxacin (CIP), gentamicin (GEN), and ciprofloxacin+gentamicin (b) ciprofloxacin, oxacillin (OXY), and ciprofloxacin+oxacillin (c) ciprofloxacin, vancomycin (VAN), and ciprofloxacin+vancomycin (d) gentamicin, oxacillin, and gentamicin+oxacillin (e) gentamicin, vancomycin, and gentamicin+vancomycin (f) oxacillin, vancomycin, and oxacillin+vancomycin.