Profile of Non-tuberculous Mycobacteria Among Tuberculosis Presumptive People

Background : Cameroon is a tuberculosis (TB) burden country with a 12% positivity among TB presumptive cases. Of the presumptive cases with a negative TB test, some are infected with Non-tuberculous Mycobacteria (NTM). However, the diagnosis of NTM infections remains difficult due to the lack of tools in many laboratories, particularly in resource limited laboratories and remote setting. The present study was undertaken to determine NTM profile and associated comorbidities among TB presumptive people. Methods: A retrospective study was conducted from December 2018 to December 2019 in the Tuberculosis-National Reference Laboratory (TB-NRL). We included in this study data of 5267 TB presumptive people previously diagnosed using three consecutive samples and having culture and SD Bioline results with or without Microscopy and reverse hybridization-based Line Probe Assay(LPA) results. The data on co-morbidities or history of people infected with NTM were then collected. Results: We collected data of 5267 presumptive TB people. Among them, 3436 (65.23%), have a positive culture with 3200 (60.75%) isolates belong to Mycobacterium tuberculosis Complex (MBTC) and 236 (4.48%) to NTM. Our results showed that, 123 (52.11 %) NTM were isolated from people with negative microscopy and 113 (47.88%) from people with positive microscopy. Among the 236 NTM, 108 (45.8%) isolates were identified using LPA. M. fortuitum was the most represented species (32.41%) followed by M. intracellulare (19.44%). Sputum had the highest proportion of NTM (56%), followed by bronchial aspirations (31%). The extra-pulmonary samples presented lower proportions of isolates compared to pulmonary samples. Some patients affected with NTM presented comorbidities as HIV infection, Pulmonary tuberculosis, Type 2 diabete, Chronic bronchitis and Alveolar pneumonia. Conclusions: Our study showed the presence of NTM strains among presumptive TB people with a predominance of M. fortuitum and M. intracellulare . It is important to implement a surveillance system of NTM in TB burden country and also to develop a point-of-care test for NTM identification in limited-resource settings.