Nontuberculous Mycobacterial Infections: A Retrospective Analysis From a Tertiary Hospital in Portugal

Introduction The prevalence of nontuberculous mycobacteria (NTM) is higher in patients with structural lung disease and in immunocompromised patients. Lung involvement is the most common. The Mycobacterium avium complex corresponds to the most identified agent. The treatment is complex and must be maintained for 12 months after cultural conversion. As it is a complex disease, the objective of this study is to carry out a demographic assessment of patients with NTM infection and evaluate the therapeutic regimens used and their adverse effects. Materials and methods A retrospective analysis of NTM isolates identified between 2012 and 2023 in a tertiary hospital in Portugal, focusing on those responsible for causing disease. The disease criteria were based on the guidelines established by the British Thoracic Society (BTS). Results We obtained a total of 35 patients with an average age of 63±15.5 years and the majority were male (n=22, 63%). Patients were divided into two groups: the group with lung disease (n=31, 89%); and the group with extra-pulmonary disease (n=4, 11%). Within the group with lung disease, 15 (48%) had previous lung disease and 13 (42%) were immunosuppressed. The most common imaging pattern was nodular/bronchiectatic (n=25, 81%). The most isolated agents were M. avium (n=10, 32%), M. intracelulare (n=7, 23%) and M. fortuitum (n=4, 13%). The average treatment time was 13.5±3.8 months and the most used regimen was rifampicin, ethambutol and clarithromycin. During treatment, four (13%) presented hepatotoxicity, three (10%) nausea/vomiting and one (3%) ototoxicity. It was possible to identify nine (29%) susceptibility profiles, with only one (11%) patient showing resistance. Within the group with extra-pulmonary involvement, all were immunosuppressed, three (75%) due to HIV infection. The affected organs were hepatic, lymph node, bone marrow and peritoneum. The isolated agents were M. avium (n=2, 50%), M. kansasii (n=1, 25%) and M. triplex (n=1, 25%). The average treatment time was 12±4.2 months. Two adverse effects were recorded: optic neuritis and nausea/vomiting. There is no data regarding the resistance profile. Discussion Pulmonary involvement was more prevalent and M. avium was the most predominant agent. Patients with pulmonary involvement had more underlying lung changes and those in the extra-pulmonary group had a greater degree of immunosuppression. The identification of NTM occurred mainly through cultural examination of sputum and bronchial secretions. The average duration of treatment was 13.5±3.8 months within the group with lung disease and 12±4.2 months within the group with extra-pulmonary involvement. The most documented adverse effects were nausea/vomiting and hepatotoxicity. Conclusion Our investigation intends to raise awareness of this pathology, which is a challenge in terms of treatment and diagnosis.