R3clone strain accounts for 70% of rifampicin-resistant TB in Rwanda and transmits across borders.

This observational study examined Mycobacterium tuberculosis isolates collected from Rwanda, Burundi, and public genomic repositories across several countries in the African Great Lakes Region. The analysis included 375 isolates, comprising 264 historical Rwandan samples (1991-2021), 49 recent Rwandan samples (2021-2024), 25 historical Burundi samples (2002-2013), and 37 from public repositories. The primary exposure assessed was the presence of the R3clone, a dominant multidrug-resistant tuberculosis strain, compared to other Mycobacterium tuberculosis complex (MTBC) sub-lineages.

The study identified the R3clone in 264 historical Rwandan isolates and 49 recent Rwandan isolates. This strain was responsible for approximately 70% of rifampicin-resistant TB cases in Rwanda. Additionally, the R3clone-specific qPCR assay demonstrated 100% specificity in distinguishing the R3clone from other MTBC sub-lineages. Evidence supports the transmission of the R3clone within the Great Lakes Region, indicating cross-border spread of this dominant strain.

No safety data, adverse events, or tolerability were reported as this was a genomic surveillance study rather than a clinical trial. A key limitation is that the presence of the R3clone beyond Rwanda remains unexplored prior to this study. While the findings underscore the necessity for coordinated international surveillance to manage cross-border transmission, the observational nature of the data precludes definitive causal inferences regarding clinical outcomes without further evidence.