IDENTIFICATION OF MYCOBACTERIUM TUBERCULOSIS COMPLEX SPECIES IN BULGARIA

Tuberculosis is caused by closely related mycobacterial species, designated as M.tuberculosis complex (MTBC), which includes : M.tuberculosis sensu stricto, M.africanum, M.canettii, M.bovis, M.caprae, M. microti. There is an increase in human TB cases caused by M.bovis or M.caprae in the EU. Although Bulgaria is not a bovine TB-free country, the species identification inside the MTBC is not routinely performed for human isolates and the presumably animal related pathogens could not be distinguished. This study aimed to reveal the presence of M.bovis/M.caprae as an aetiological agent on the territory of Bulgaria. For the period from 2022 to 2025, a total of 175 MTBC strains were further examined to differentiate the species. GenoType MTBC VER 1.X was used as a reliable identification tool. Almost all cases were found to be M.tuberculosis/M.canettii (n=173; 98.85%). The prevalence of Mycobacterium bovis was 0.57%. M.bovis BCG also was represented by a single isolate (0.57%). M.africanum, M.microti, or M.caprae have not been detected so far. Species identification in the MTBC is an essential step in order to limit the transmission from animal to human and to refine the treatment of the affected individuals.