Enrollment has begun in an early-stage clinical trial evaluating bacteriophage therapy in adults with cystic fibrosis (CF) who carry Pseudomonas aeruginosa (P. aeruginosa) in their lungs. The trial is evaluating whether the bacteriophage, or “phage,” therapy is safe and able to reduce the amount of bacteria in the lungs of volunteers. The trial is being conducted by the Antibacterial Resistance Leadership Group (ARLG), funded by the National Institute of Allergy and Infectious Diseases. Investigators aim to enroll up to 72 adults at 16 CF centers across the United States.