Treatment outcomes of multi-drug-resistant and rifampicin-resistant tuberculosis with and without isolation of nontuberculous mycobacteria between 2018-2021: A retrospective cohort study in Ghana

Abstract

Multi-drug-resistant and rifampicin-resistant tuberculosis (MDR/RR-TB) pose an urgent health threat in Ghana. Despite ongoing interventions, the outcomes for MDR/RR-TB in Ghana have remained suboptimal over recent years. During this period, there has been an increasing detection of nontuberculous mycobacteria (NTM) in mycobacterial cultures. We sought to examine if the isolation of NTM could be a factor contributing to unfavourable MDR/RR-TB treatment outcomes. We also estimated predictors of NTM isolation, including using the short-course injectable-containing regimen (SCI) versus the all-oral bedaquiline (SCO) regimen and other covariates. This retrospective cohort study analysed MDR/RR-TB patients in Ghana from 2018 to 2021 across four regions. Demographic, clinical, and diagnostic data were collected under the National Tuberculosis Control Program framework. Mycobacterial smears and cultures were used to monitor treatment response, with further identification of NTM using line probe assays and Sanger sequencing. Multivariable logistic regression models evaluated predictors of NTM isolation and having an unfavourable outcome. Of 427 identified MDR/RR-TB patients, 380 were included for analysis: 76.3% were male, the mean age was 43.9 years, and 18.9% were people living with HIV. NTM were isolated in 7.1% of cases, primarily Mycobacterium intracellulare and M. fortuitum, with higher odds of isolation in individuals from the Eastern Region (aOR:14.18, 95% CI: 3.95-50.92). Overall, 67.9% achieved favourable outcomes: 71.4% (185/259) in those on the SCO versus 60.3% (73/121) on the SCI regimen. People living with HIV (aOR 14.18, 95% CI: 3.95-50.92) had an increased odds of having an unfavourable outcome. NTM isolation was not associated with unfavourable outcomes. Our study results suggest that although NTM isolation may occur during the course of MDR/RR-TB treatment, it does not affect MDR/RR-TB treatment outcome. Future research should further explore the implications of NTM co-infection on longer-term MDR/RR-TB outcomes, such as post-TB lung disease, to refine management strategies tailored to the reality of low-resource, high-burden settings.

Fig 1. Patient identification and inclusion.