BACKGROUND:Bronchiolitis obliterans syndrome (BOS) after lung transplantation manifests as a gradual decline in forced expiratory volume in 1 second. Bronchiectasis is often seen but occurs at variable rates with the underlying pathogenesis being unclear. OBJECTIVE:We completed a study to determine whether lower airway infection with gram-negative bacilli was associated with the development of bronchiectasis in lung transplant recipients with BOS. METHODS:A retrospective review of 17 lung transplant recipients (age: 28 ± 7 years, range: 13 to 40 years) in a patient population transplanted for cystic fibrosis (CF) 82% (14/17), bronchiolitis obliterans 12% (2/17), and sarcoidosis 6% (1/17) was completed. Each patient completed pulmonary function testing and underwent annual computed tomographic imaging of the chest for surveillance posttransplant at a single transplant center. RESULTS:Bronchiectasis was present in 70% (12/17) of patients whereas 94% (16/17) of patients had varying severity of BOS: 1 (n = 7), 2 (n = 3), and 3 (n = 6). All 12 patients with bronchiectasis had an allograft gram-negative rod infection and 92% (11/12) of them had BOS. CONCLUSIONS:The presence of bronchiectasis in lung transplant recipients with BOS was associated with a gram-negative bacterial airway infection of the allograft in a small cohort of predominately lung transplant recipients with CF.