Non-tuberculous mycobacteria: clinical and laboratory characterisation (2009 and 2019)

A cross-sectional and retrospective study of patients with Mycobacterium spp. in a Portuguese tertiary hospital, in 2009 and 2019, was performed to understand better the rise in isolations of nontuberculous mycobacteria (NTM). The number of patients with positive samples for Mycobacterium spp. grew from 56 in 2009 to 83 in 2019. The proportion of NTM rose from 39.3% to 49.4% (P = 0.240), with Mycobacterium avium complex being more frequent in 2009 and Mycobacterium gordonae in 2019, and Mycobacterium tuberculosis complex decreased from 60.7% to 50.6%. Higher age was associated with NTM in both years, and pulmonary disease and immunosuppression were associated with NTM in 2019 (P < 0.05), with weak to moderate correlation (V = 0.231–0.343). The overall rise of NTM, allied to their known capacity to resist antimicrobial therapy, alerts clinicians to the importance of recognising potential risk factors for infection and improving future prevention strategies.