Highly successful treatment outcome of multidrug-resistant and genetic diversity of multidrug-resistant Mycobacterium tuberculosis strains in Rwanda

Abstract

Objective: To determine prevalent MDR-TB genotypes and describe treatment outcome and bacteriology conversion in MDR-TB patients. Methods: Review of laboratory records of 173 MDR-TB patients from all over Rwanda who initiated treatment under programmatic management of MDR-TB (PMDT) between 2014 and 2015. Fifty available archived isolates were genotyped by mycobacterial interspersed repetitive units – variable number of tandem repeats (MIRU-VNTR) genotyping. Result: Of the 170 patients whose outcome was known, 114 (66.3%) were cured and 36 (21%) completed the treatment, giving a successful outcome (cured and completed) of 150 (87.3%) patients. Of 20 MDR-TB patients with unfavourable treatment outcome, 18 died, one failed and one defaulted/stopped treatment. Of the 18 patients who died, 11 (61%) were HIV-coinfected. The treatment outcome was successful for 93.9% among HIV negative and 81.8% among HIV-coinfected patients (P = 0.02). Sputum smear conversion occurred in 3, 46, 57 and 78 patients before 2, 3, 4 and 6 months, respectively, with median time of sputum smear and culture conversion at 3 months. The 44 MDR-TB isolates with MIRU-VNTR result, showed high genetic diversity with low clustering rate (9.09%) and Uganda II being the most prevalent sub-family lineage detected in 68.2% of isolates. Beijing family was the least common genotype detected (2.3%, 1 isolate). Conclusion: The high success rates for MDR-TB treatment achieved in Rwanda were comparable to outcomes observed in resource-rich settings with HIV being an independent risk factor for poor treatment outcome. High genetic diversity and low clustering rate reported here suggest that reactivation of previous disease plays an important role in the transmission of MDR-TB in Rwanda.