Modern lineages of Mycobacterium tuberculosis in Addis Ababa, Ethiopia: implications for the tuberculosis control programe

A Mihret, Y Bekele, M Aytenew, M Abebe, L Wassie, GA Loxton, L Yamuah, A Aseffa, G Walzl, R Howe

Abstract

Background: The genotyping of Mycobacterium tuberculosis strains is important to have unique insights into the dissemination dynamics and evolutionary genetics of this pathogen and for TB control as it allows the detection of suspected outbreaks and the tracing of transmission chains.

Objective: To characterize M. tuberculois isolates collected from newly diagnosed pulmonary TB patients in Addis Ababa Methods: One hundred and ninety two sputum samples were cultured on Löwenstein-Jensen (LJ) slants and isolates were heat killed for molecular genotyping. The isolates were characterized using spoligotyping and were compared with the International SpoIDB4 database.
Result: T genotype constitutes the most predominant in our study (95, 49.5%) followed by the CAS genotype (42, 21.9%). Other genotypes found were Haarlem (H) (24, 12.5%), the LAM (3, 1.5%), the Beijing genotype (1, 0.5%); four (2.1%) isolates were designated as Unknown.

Conclusion: All the isolates belong to the modern lineage and there is high clustering in the genotype of isolates which indicated the presence of recent TB transmission. Therefore, the Tuberculosis Control Programme needs to do more in advocating and strengthening the health system for early detection and treatment of active TB cases as delay in treatment is
the key factor in disease transmission.

Key words: Mycobacterium, genotype, recent transmission, spoligotyping