Nontuberculous Mycobacteria in Primary Ciliary Dyskinesia: A National Multicenter Cohort Study

Introduction: The prevalence and clinical significance of nontuberculous mycobacteria (NTM) in individuals with primary ciliary dyskinesia (PCD) remain unclear, with most data extrapolated from cystic fibrosis. This first national multicenter cohort study evaluating NTM in PCD patients aimed to determine the prevalence, species distribution, and clinical impact of NTM isolation. Methods: A retrospective, longitudinal study was conducted across four tertiary centers in Israel (2010–2024). Patients with confirmed PCD were evaluated for demographic, clinical, microbiological, and longitudinal lung function data. NTM species were classified by growth rate and pathogenicity. Each NTM-positive PCD patient was matched 1:1 to an NTM-negative PCD patient. Results: Of 231 patients with PCD, 24 (10.4%) had ≥1 positive NTM culture. Most isolates were slow-growing species, predominantly Mycobacterium simiae. Rapid-growing species, mainly Mycobacterium abscessus, were identified in patients with significantly lower forced expiratory volume in 1 s (FEV1) at the time of NTM isolation when compared with those harboring slow-growing species (43.5% vs. 82.3%, p = 0.03). Chronic isolation occurred in 25% of NTM-positive individuals. Longitudinal analysis showed no significant association between NTM status and FEV1 decline. Intravenous antibiotic use was not higher in NTM-positive patients and did not increase following NTM isolation. Only one patient fulfilled the criteria for NTM pulmonary disease. Conclusion: NTM isolation is not uncommon in PCD patients and is often intermittent, mostly by slow-growing species. NTM status was not associated with accelerated FEV1 decline, although rapid growers occurred predominantly in patients with poorer baseline lung function. Routine annual NTM surveillance appears reasonable to better determine prevalence and monitor outcomes.