Figure 3.

Emergent synergistic and antagonistic interactions in triple antibiotic combinations. Data for triple antibiotic figures are shown according to E3 interaction measures. Figures are presented as described in figures 1 and 2. Data are represented as median ± minimum/maximum. (a) The combination of ciprofloxacin 0.013 µg ml⁻¹ (CPR), clindamycin 31.5 µg ml⁻¹ (CLI) and erythromycin 14 µg ml⁻¹ (ERY) interacts synergistically in three-drug combinations according to both DA and emergent (E3) measures. (b) The combination of ERY 14 µg ml⁻¹, cefoxitin 1.16 µg ml⁻¹ (FOX) and tobramycin 1.3 µg ml⁻¹ (TOB) interacts antagonistically in three-drug combinations according to the E3 measure and additively according to the DA measure. Only data for one concentration of each antibiotic are shown, although each three-drug combination was tested in a minimum of three independent experiments (see Material and methods).