OPTIMIZing Treatment for Early Pseudomonas Aeruginosa Infection in Cystic Fibrosis

Cystic fibrosis (CF) lung disease begins in the first few months of life and follows a course of recurrent lower airway bacterial infection and inflammation and progression of disease over years and decades at a variable pace. With the development of chronic lung infection, obstructive disease progressively worsens, ultimately leading to respiratory failure. Pseudomonas aeruginosa (Pa) is the most important pathogen infecting the CF lower airways, and its acquisition early in life is associated with a pro-inflammatory effect, lower lung function, poor nutritional outcomes, and decreased survival. Pseudomonas aeruginosa (Pa) infection of the cystic fibrosis (CF) airway typically proceeds from early infection to chronic infection. Although some studies have shown that a minority of individuals with CF spontaneously clear early Pseudomonas aeruginosa (Pa) infection, data from multiple studies suggest that antibiotics are superior to no treatment in clearing Pseudomonas aeruginosa (Pa) from respiratory cultures. Understanding the transition period from early to chronic Pseudomonas aeruginosa (Pa) infection is thus of critical importance in identifying strategies to prevent this progression. The study will assess the clinical and microbiologic efficacy and safety of azithromycin given three times weekly in combination with standardized tobramycin solution for inhalation (TIS) therapy among children with early Pseudomonas aeruginosa (Pa). TIS therapy is defined as an initial eradication treatment with 1-2 courses of 28 days TIS and subsequent 28 day treatments only at times a quarterly respiratory culture is positive for Pseudomonas aeruginosa (Pa). Eligible participants will be randomized within one month of their Pseudomonas aeruginosa (Pa) positive culture to receive one of the following two treatment strategies for 18 months: (1) oral placebo in addition to standardized TIS therapy, or (2) oral azithromycin in addition to standardized TIS therapy. At the first study visit, participants will undergo a physical examination and a review of their medical history. Lung function will be measured via spirometry (in children greater than four years of age who are able to perform spirometry), electrocardiogram (ECG) testing will be conducted, and hearing ability will be measured via audiometry. Blood will be drawn for laboratory tests and a specimen will be obtained for a respiratory culture before randomization and study drug dispensing occurs. Subsequent study visits will take place at Day 21, Weeks 13, 26, 39, 52, 65, and 78. At each visit, participants will undergo a physical examination, a spirometry test (as appropriate), a respiratory specimen for Pseudomonas aeruginosa (Pa) culture will be collected and study drug will be dispensed (except at Week 78). Participants will complete self-report or parent-completed respiratory symptom questionnaires and signs and symptoms evaluations will be performed at all visits. Repeat hearing and laboratory tests will be performed at Weeks 39 and 78 and ECG testing will be repeated at Day 21 and Week 78. Participants will be required to maintain a medication diary throughout the study.