Cases series on nontuberculous mycobacterial (NTM) lung disease and silicosis in Brazil

NTM contributes to morbidity and mortality in silica exposed population, which remains high in Brazil. Data point to a general increase in NTM disease diagnostics. Since there is few literature in this matter, patients treatment guidance greatly depends upon expertise on the subject, making it important to generate information to better care for these patients. It is a report of 12 patients with silicosis and NTM lung disease (according to American Thoracic Society criteria - 2007) in a tertiary hospital in Brazil from 2008 to 2017. Data were collected from patients9 records and clinical features were described. All cases, but one (accelerated form), were men (median age 48,5 years) with chronic silicosis (median exposure time 11 years). Three had rheumatoid arthritis (RA) in use of methotrexate. Half had previous pulmonary tuberculosis treatment. Most patients (8/11 - 73%) had image compatible with progressive massive fibrosis and 50% had FEV1 below 50% of predicted, showing a more severe silicosis involvement among NTM cases. There was one case of pleural effusion due to M. kansasii. Nine cases (75%) included cavitary lesions and three (25%) had bronchiectasis. The NTM species were: M. kansasii (eight), M. avium complex (two), M. abscessus (one), and M. smegmatis (one) - unique case in literature in a patient with silicosis and RA. The cure rate, after mean treatment time of 18 months, was 78% (7/9). It is important to insistently evaluate mycobacteriosis with several microbiological techniques, since silicosis may make it difficult to observe radiological or clinical changes of an active mycobacterial disease, especially for NTM. The correct diagnosis has relevant therapeutic implications.