Analysis of Mycobacterium africanum in the last 17 years

The purpose of this study was to increase our knowledge about Mycobacterium africanum and report the incidence and characteristics of tuberculosis (TB) due to their lineages in Aragon, Spain, over the period 2003–2019. The study includes all the cases in our region, where all the M. tuberculosis complex isolates are systematically characterised. We detected 31 cases of M. africanum among 2598 cases of TB in the period studied. TB caused by M. africanum is rare (1.19%) in our population, and it affects mainly men of economically productive age coming from West African countries. Among the isolates, Lineage (L) 6 was more frequent than L5. The genotyping of these strains identified five clusters and 13 strains with a unique pattern.

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Fig: Dendrogram based on spoligotype patterns. The data shown are spoligotypes, IS6110-RFLP types, isolate number, year of isolation, SIT, family under SITVIT definition, and lineage of each M. africanum isolate in our population from 2003 to 2019. For two isolates, RFLP-type was not available, both showing a unique spoligotype belonged to AFRI and AFRI1 families. *Isolate 2 in CLS_AFRI_1 has a different location of one copy of IS6110 despite sharing the RFLP pattern with the other five isolates included in its cluster.

The isolates’ characterisation identified a copy of IS6110 within the moaX gene, which turned out to be specific for L6. It will allow the differentiation of this lineage from the rest of MTBC with a simple PCR reaction. It remains to be established whether this polymorphism may limit M. africanum transmission. Furthermore, a mutation in the mutT2 promoter was found as specific for L6 strains, which could be related to the high variability found for L6 compared to L5.

Comín, J., Monforte, M.L., Samper, S. et al. Analysis of Mycobacterium africanum in the last 17 years in Aragon identifies a specific location of IS6110 in Lineage 6. Sci Rep 11, 10359 (2021). https://doi.org/10.1038/s41598-021-89511-x

 

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