Cystic Fibrosis Foundation (CFF) treatment guidelines for the management of pulmonary exacerbations (PEx) identified evidence gaps in current clinical best practices. The STOP program offers a platform for the conduct of controlled trials to develop the evidence base in order to define clinical best practices. The interventional Aminoglycoside Study (AG Study) will be a prospective, multi-center, parallel group, randomized (1:1 ratio), open-label, superiority study of intravenous aminoglycoside and β-lactams versus intravenous β-lactams only. Randomization will occur at Visit 1. The primary objective of this platform trial is to evaluate the efficacy and safety of differing treatments in CF PEx during a planned 14 day course of IV antimicrobials. Primary efficacy will be evaluated as the difference in mean Percent Predicted Forced Expiratory Volume in 1 Second (ppFEV1) changes from Visit 1 to Visit 2 (Day 28 ± 2 days) between intervention arms.