Pharmacologic improvement of CFTR function rapidly decreases sputum pathogen density, but lung infections generally persist oleh David P. Nichols, Sarah J. Morgan, Michelle Skalland, Anh T. Vo, Jill M. Van Dalfsen, Sachinkumar B.P. Singh, Wendy Ni, Lucas R. Hoffman, Kailee McGeer, Sonya L. Heltshe, John P. Clancy, Steven M. Rowe, Peter Jorth, Pradeep K. Singh, the PROMISE-Micro Study Group