Association of D516V, H526Y, and S531L rpoB gene polymorphisms and risk factors with rifampicin resistance in Mycobacterium tuberculosis isolates from pulmonary TB patients in Northwest Amhara, Ethiopia: cross-sectional study.

BACKGROUND

Drug-resistant tuberculosis (DR-TB) continues to pose a threat to public health worldwide. Rifampicin (RIF) resistance is mostly caused by mutations in the rpoB gene, which codes for the β -subunit of RNA polymerase and is also an important surrogate marker for multidrug-resistant tuberculosis (MDR).

OBJECTIVE

This study aimed to detect the rpoB gene mutations associated with RIF resistance and identify the risk factors for MDR/ RIF resistance patterns in individuals infected with pulmonary TB.

METHODS

A facility-based cross-sectional study was conducted at selected TB treatment center hospitals (Felegehiwot, Debre-tabor, University of Gondar, Debark, and Metema hospitals) from June to December 2023 in the Northwestern Amhara regional state of Ethiopia. A total of 206 pulmonary TB patient's sputum samples were included. The study participants' Socio-demographics and clinical and behavioral characteristics were collected through semi-structured questionnaires. Then all GeneXpert® MTB/RI-positive sputum specimens of bacterial isolates were culturedin a conventional egg-based solid Lowenstein-Jensen (LJ) medium. MTB Genomic DNA was extracted using GenoLyze Kit. The allele-specific Amplification Refractory Mutation System Polymerase Chain Reaction (ARMS PCR) approach was employed on whole DNA samples from 206 Culture positive isolates using three distinct codon-specific primers (D516V, H526Y, and S531L).

RESULTS

An isolate is classified as RR-TB if it carries any mutation in the rpoB gene. Most Single nucleotide polymorphism (SNP) mutations were observed on rpoB S531L 19 (9.2%). Of 206 confirmed clinical isolates, 21 (10.2%) were RIF Resistant, while the remaining 185 (89.8%) were RIF susceptible. Before TB treatment history (AOR = 4.27, CI 1.29-14.20, p = 0.02), and Window opening practice of patients (AOR = 6.17, CI 1.22-31.29, p = 0.03) were significantly associated with RR-TB development.

CONCLUSION

The prevalence of RR (RIF Resistant) -TB among TB-confirmed cases was 21 (10.2%). This implies that RR-TB is a serious health problem in the study population. The S531L was the most common mutation conferring resistance to RIF.

CLINICAL TRIAL NUMBER: Not applicable.