Nontuberculous mycobacterial lung disease in a high tuberculosis incidence setting in Brazil

Maiara dos Santos Carneiro, Luciana de Souza Nunes, Simone Maria Martini De David, Claudia Fontoura Dias, Afonso Luís Barth, Gisela Unis

The incidence of lung disease caused by nontuberculous mycobacteria (NTM) has been increasing worldwide. In Brazil, there are few studies about nontuberculous mycobacterial lung disease (NTMLD), and its prevalence is yet to be known. Our objective was to determine the specific etiology of the disease in the state of Rio Grande do Sul, Brazil, as well as the frequency and diversity of NTM species in our sample of patients. This is a retrospective analysis of the medical records of patients diagnosed with NTMLD treated in a referral center located in the city of Porto Alegre, Brazil, between 2003 and 2013. Our sample comprised 100 patients. The most prevalent NTM species were Mycobacterium avium complex (MAC), in 35% of the cases; M. kansasii, in 17%; and M. abscessus, in 12%. A total of 85 patients had received previous treatment for tuberculosis. Associated conditions included structural abnormalities in the lungs, such as bronchiectasis, in 23% of the cases; COPD, in 17%; and immunosuppressive conditions, such as AIDS, in 24%. MAC and M. kansasii were the most prevalent species involved in NTMLD in the state, similarly to what occurs in other regions of Brazil. Data on regional epidemiology of NTMLD, its specific etiology, and associated conditions are essential to establish appropriate treatment, since each species requires specific regimens. Most patients with NTMLD had received previous tuberculosis treatment, which might lead to development of resistance and late diagnosis.