Rationale: Bronchiectasis is a chronic debilitating disease with few evidence-based long-term treatments.

Objectives: A randomized controlled trial assessing the efficacy of nebulized gentamicin therapy over 1 year in patients with non-cystic fibrosis bronchiectasis.

Methods: Sixty-five patients were randomized to either twice-daily nebulized gentamicin, 80 mg, or nebulized 0.9% saline, for 12 months. All were reviewed at three-monthly intervals during treatment and at 3 months' follow-up.

Measurements and main results: At each review the following were assessed: quantitative and qualitative sputum bacteriology; sputum purulence and 24-hour volume; FEV(1), FVC, and forced expiratory flow, midexpiratory phase; exercise capacity; Leicester Cough Questionnaire and St. George's Respiratory Questionnaire; and exacerbation frequency. Fifty-seven patients completed the study. At the end of 12 months' treatment, compared with the saline group, in the gentamicin group there was reduced sputum bacterial density with 30.8% eradication in those infected with Pseudomonas aeruginosa and 92.8% eradication in those infected with other pathogens; less sputum purulence (8.7% vs. 38.5%; P < 0.0001); greater exercise capacity (510 [350-690] m vs. 415 [267.5-530] m; P = 0.03); and fewer exacerbations (0 [0-1] vs. 1.5 [1-2]; P < 0.0001) with increased time to first exacerbation (120 [87-161.5] d vs. 61.5 [20.7-122.7] d; P = 0.02). The gentamicin group had greater improvements in Leicester Cough Questionnaire (81.4% vs. 20%; P < 0.01) and St. George's Respiratory Questionnaire (87.5% vs. 19.2%; P < 0.004) score. No differences were seen in 24-hour sputum volume, FEV(1), FVC, or forced expiratory flow, midexpiratory phase. No P. aeruginosa isolates developed resistance to gentamicin. At follow-up, all outcome measures were similar to baseline.

Conclusions: Regular, long-term nebulized gentamicin is of significant benefit in non-cystic fibrosis bronchiectasis but treatment needs to be continuous for its ongoing efficacy. Clinical trial registered with www.clinicaltrials.gov (NCT 00749866).