Figure 2.

Fixed points of the model, from equation (7), plotted as a function of the external antibiotic concentration a_ex, for the two parameter sets given in table 1, corresponding to antibiotics with large and small values of ${\lambda }_0^{*}$. Panel (a) shows results for a low-affinity antibiotic, with a large value of ${\lambda }_0^{*}$ (table 1). Panel (b) shows results for a high-affinity antibiotic, with a small value of ${\lambda }_0^{*}$ (table 1). The fixed points were obtained numerically in Python using sympy.solvers.solve. The external antibiotic concentration is scaled by the IC₅₀ value calculated from equation (8) and given in table 1.