Drug resistance profile and species diversity in tuberculosis mycobacteria isolated from patients with presumptive tuberculosis in Brazzaville, Republic of Congo

• Dominance of M. tuberculosis sensu stricto over M. africanum • High prevalence of non-tuberculous mycobacteria in isolates • Significant monoresistance to first-line anti-TB drugs observed • MDR-TB prevalence at 7%, indicating rising treatment failure risk • Provides key data to guide TB control in Central Africa Speciation of tuberculosis (TB) -causative organisms and drug sensitivity testing are important for TB management in high tuberculosis burden countries such as the Republic of Congo. This study determined both the species diversity of Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacterial isolates and their phenotypic drug profile circulating in Brazzaville, the Republic of Congo. A cross-sectional study involving 92 naïve patients with presumed pulmonary tuberculosis hospitalised at the Makelekele Hospital between October 2018 and October 2019. Liquid culture by the MGIT 960 system (Becton Dickinson) was applied for mycobacteria identification. Differentiation of MTBC organisms from non-tuberculosis mycobacteria was done using the BD MGIT™ TBc Identification Test. Species-level identification within the MTBC was performed using the Bruker HAIN Line Probe Assay MTBC. Drug susceptibility testing was performed using the indirect proportion method on the BACTEC MGIT 960 system). Out of the 92 pulmonary TB presumptive enrolled, 48 (52.17%) were culture positive. Among those, 7/48 (14.6%) were non-tuberculous mycobacteria and 41/48 (85.4%) were identified as MTBC isolates. The MTBC strains were 80% M. tuberculosis (33/41) and 20% M. africanum (8/41). Monoresistance was determined as to rifampicin 29.3% (12/41), isoniazid 22% (9/41), ethambutol 26.8% (11/41) and streptomycin 4.88% (2/41), respectively. Multidrug resistance (isoniazid and rifampicin) was detected in 7.3% (3/41). This finding highlights a predominance of Mycobacterium tuberculosis , alongside a notable presence of M. africanum and non-tuberculous mycobacteria. The observed resistance profile, characterized by high rates of monoresistance underscores the urgent need to strengthen diagnostic capacity, genomic surveillance, and integrated prevention strategies to effectively monitor and contain the spread of drug-resistant MTBC and non-MTN strains.