To evaluate the impact of bacterial adaptation to the CF lung on the antimicrobial activity of CFTR modulators, we measured minimum inhibitory concentrations (MICs) for clinical clonal isolates collected from CF patients at early and late stages of chronic colonization and previously characterized (see Tables S1 and S2 in the supplemental material) (34, –, 37). The gene discussed is CFTR; the disease is cystic fibrosis.