Background: Molecular identification of mutations resulting in multidrug-resistant tuberculosis (MDR-TB) is an important
approach for improving understanding of MDR-TB epidemiology and planning for appropriate interventions. We aimed
to estimate the prevalence and distribution of mutations causing MDR-TB as well as determine the gene distribution among
patients previously treated for TB.
Methods: This was a cross-sectional, hospital-based study conducted from April 2017 to October 2018 at Kibong’oto Infectious
Diseases Hospital (KIDH). KIDH is the national MDR-TB referral hospital. Participants were patients presumptively diagnosed
with MDR-TB and referred to KIDH from district and regional hospitals across Tanzania. Sputum samples were collected
and analysed using the Xpert MTB/RIF assay, direct sputum smear fluorescence microscopy, culture on Lowenstein-Jensen
medium, and line probe assay using the GenoType MTBDRplus VER 2.0 system. Demographic information and mutation frequencies
were reported as counts and percentages and analysed using descriptive statistics.
Results: A total of 208 (69.3%) participants had rpoB gene mutations conferring resistance to only rifampicin; 92 (30.7%)
had rpoB, katG, and inhA mutations conferring resistance to rifampicin and isoniazid; 78 (26%) had rpoB and katG mutations
conferring resistance to rifampicin and isoniazid; and 14 (4.7%) had rpoB and inhA mutations conferring resistance to
rifampicin and isoniazid.
Conclusion: The mutation prevalences identified in this study indicate the most frequent mutations were the S531L mutation
of the rpoB gene, the S315T1 mutation of the katG gene, and the S315T mutation in the promoter region of the inhA gene.
To control the emergence and spread of MDR-TB, drug sensitivity testing must be carried for GeneXpert-confirmed TB patients
prior to initiating second-line anti-TB regimens.