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

OBJECTIVES

Speciation of tuberculosis (TB) causative organisms and drug sensitivity testing are important for TB management in high-TB burden countries, such as the Republic of Congo. This study determined the species diversity of Mycobacterium tuberculosis (MTB) complex (MTBC) and non-tuberculous mycobacterial isolates and their phenotypic drug profile circulating in Brazzaville, the Republic of Congo.

METHODS

A cross-sectional study involving 92 naïve patients with presumed pulmonary TB hospitalized 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-TB 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.

RESULTS

Of the 92 pulmonary TB presumptive enrolled, 48 (52.17%) were culture-positive. Among those, seven of 48 (14.6%) were non-tuberculous mycobacteria and 41 of 48 (85.4%) were identified as MTBC isolates. The MTBC strains were 80% M. tuberculosis (33 of 41) and 20% Mycobacterium africanum (eight of 41). Monoresistance was determined as to rifampicin 29.3% (12 of 41), isoniazid 22% (nine of 41), ethambutol 26.8% (11 of 41), and streptomycin 4.88% (two of 41), respectively. Multidrug resistance (isoniazid and rifampicin) was detected in 7.3% (three of 41).

CONCLUSION

This finding highlights a predominance of M. 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-TB mycobacteria strains.