Patient's features, clinical patterns and outcomes of non-tuberculous mycobacteria infections: A 10-year retrospective analysis from a third level university hospital.

Background: Non-tuberculous mycobacteria (NTM) increasingly recognized as clinically relevant pathogens, particularly in immunocompromised individuals and patients with structural lung disease. Despite their growing clinical impact, real-world data on NTM infections in Europe remain limited. Methods: We conducted a retrospective cohort study in adults diagnosed with NTM infections at a 1700-bed tertiary care hospital in Italy between 2015 and 2024. Data were collected on demographics, comorbidities, radiological and microbiological findings, treatment regimens, and outcomes. Multivariable Cox regression analyses were performed to identify factors associated with treatment failure, overall mortality, and NTM-attributable mortality. Results: Among 149 treated patients (median age: 68 years; 60.4% female), the most prevalent species were Mycobacterium avium (38.9%), M. intracellulare (29.5%), and M. kansasii (8.7%). Pulmonary disease was observed in 87.9%, with radiologic findings commonly including nodules (67.8%) and bronchiectasis (64.6%). Clinical cure was achieved in 52.3%, while 47.7% experienced treatment failure. The relapse rate was 9.4%. All-cause and NTM-attributable mortality were 14.8% and 4.7%, respectively. Treatment failure was significantly associated with cavitary disease. Attributable mortality was independently associated with older age, , previous tuberculosis, cancer, autoimmune disorders, and use of nebulized amikacin. Conclusions: NTM infections remain challenging to manage, particularly among patients with comorbidities and immunosuppression. Our findings highlight the need for individualized care strategies, multidisciplinary approach, improved diagnostics, and enhanced surveillance of NTM infections in Europe.