A Preliminary Study on Molecular Characterization of Mycobacterium tuberculosis in Benishangul Gumuz Region, Western Ethiopia

Background: The information about the genetic diversity of Mycobacterium tuberculosis in certain geographic area is needed for a better understanding of epidemiology of tuberculosis and could have implications for development of new diagnostics, drugs, and vaccines. The aim of this study was to provide preliminary information on the strains of Mycobacterium tuberculosis circulating in Benishangul Gumuz Region.

Methods: Cross-sectional study was conducted to generate preliminary information on the genetic diversity of Mycobacterium tuberculosis between November 2012 and April, 2013. Mycobacterium tuberculosisisolates were characterized using region of difference 9 (RD9) and spoligotyping. The patterns of strains identified by spoligotyping were compared with the patterns registered in the SpoIDB4 database of the Pasteur Institute.

Results: Out of a total of 53 smear positive samples, 34 (64.15%) were culture positive, of which, 33 samples were confirmed to be Mycobacterium tuberculosis by RD9 deletion typing. Further characterization of 33 isolates using spoligotyping lead to the identification of 24 individual spoligotype patterns, among which, 18 were unique while the remaining six were found in clusters containing two to four isolates. Of the 24 patterns identified by the present study, only six patterns were registered in SpolDB4 international database, while 18 patterns were not previously registered in the database. Grouping of the 33 isolates into the lineages showed that 19 (57.6%) isolates were members of Euro-American, 6 (18.2%) isolates were Indo-Oceanic while the remaining 8 (24.2%) could not be categorized to the presently known lineages.

Conclusion: Characterization of the Mycobacterium tuberculosis strains revealed the identification of new strains and lineages which could not match with the existing strains and lineages suggesting the localization of these strains and lineages in this Region. Hence, further research is required to identify and document the strains and lineages circulating in the Region.