The Role of Nontuberculous Mycobacteria in Patients With Cystic Fibrosis Advanced Lung Disease

Background: Despite decreased morbidity and mortality in patients with cystic fibrosis (CF) with CFTR modulators, a significant percentage still develop advanced lung disease. Nontuberculous mycobacteria (NTM) remain challenging pathogens with unclear effects on disease progression and post-transplant outcome. Methods: NTM-positive patients were identified from all CF patients treated at the University Hospitals of Zurich and Lausanne between 1998 and 2020. Disease course pre- and post-transplant was recorded, and NTM-positive patients were compared to patients without NTM infection for death or lung transplantation, as well as post-transplant survival and development of chronic lung allograft dysfunction (CLAD). Results: Of 270 patients, 56 (20.7%) met criteria for NTM positivity (two independent cultures with the same organism), with Mycobacterium abscessus complex (MABSC) being the most common species (75.0%). Death or transplantation occurred in 12 of 56 (21.4%) NTM-positive patients and 92 of 198 (46.5%) NTM-negative patients (OR 3.17; 95% CI, 1.53-7.00; p = 0.001). Post-transplant mortality was higher in the NTM-positive cohort (3 (27.3%) vs. 12 (13.0%); HR, 4.01, 95% CI, 1.08-14.86; p = 0.024), while CLAD incidence did not differ significantly. Conclusion: NTM-positive CF patients were associated with a lower pre-transplant risk of death or transplantation. Post-transplant mortality was higher in NTM-positive patients, while no association between NTM infection and CLAD was observed. These findings indicate that favorable outcomes after lung transplantation are achievable in NTM-positive patients. Thus, NTM-infection should not be an absolute contraindication for lung transplantation, though careful individual assessment is essential due to the risk of serious complications.