The pattern of rpoB gene mutation of Mycobacterium tuberculosis and predictors of rifampicin resistance detected by GeneXpert MTB/RIF assay in Tanzania.

Introduction: Antimicrobial resistance in Mycobacterium tuberculosis (MTB) poses a significant challenge to tuberculosis (TB) management worldwide. Rifampicin resistance (RR) has been associated with the rpoB gene mutation. No study was conducted in Tanzania to determine the commonest mutation. The inconsistent findings from various studies support the need to determine whether reported mutation patterns are applicable in our setting. We determined the frequency of rpoB gene mutation and factors associated with RR, which were detected using GeneXpert MTB/RIF assay.

Methods: We conducted a retrospective cross-sectional study involving data from the National Tuberculosis and Leprosy Program database from 2020 to 2022 for cases investigated using GeneXpert MTB/RIF assay. Descriptive analysis was performed to determine the frequency of categorical variables. The chi-square test and logistic regression analysis assessed the relationship between the independent variables and outcome. The 95% confidence interval and a significance level of p<0.05 were used to assess the strength of association.

Results: A total of 56,004 participants had a status of MTB and RR, where 38,705/56,004 (69.11%) were males. Probe E mutation (codon 529-533), 89/219 (40.64%) was predominant. Human immunodeficiency virus (HIV)-positive patients had a higher gene mutation, 134/10601 (1.26%) than HIV-negative, 306/45016 (0.68%) (p<0.001). Patients with both pulmonary and extra-pulmonary TB had about four times greater odds of developing rifampicin resistance (AOR 3.88, 95%CI: 1.80-8.32). RR was nearly nine times higher in previously treated patients than new patients (AOR 8.66, 95% CI: 6.97-10.76). HIV-positive individuals had nearly twice the odds of developing RR than HIV-negative individuals (AOR 1.91, 95%CI: 1.51-2.42).

Conclusion: The rate of RR was lower compared to other studies in Tanzania, with probe E mutations the most prevalent. Patients with disseminated TB, HIV co-infection and those with prior exposure to anti-TB had more risk of RR. The findings highlight the need to strengthen surveillance of multidrug-resistant TB among high risk patients.