CFTR and pneumonia: We designed the study to (i) determine the antimicrobial activity of CFTR modulators and their additive or synergistic effects with antibiotics against P. aeruginosa and S. aureus reference and clonal isolates collected from CF patients at early and advanced stages of lung colonization; and (ii) evaluate the concentration of IVA, as a model CFTR modulator, in plasma and airway samples and its changes during pneumonia in mice.