Saurabh Negi, Malvika Singh, Iva Chandola, Jagdish Rawat
Introduction Tuberculosis (TB) remains a major global health problem, and the emergence of drug-resistant Mycobacterium tuberculosis poses a significant challenge to disease control. Rifampicin resistance, which is predominantly associated with a mutation in the rpoB gene, serves as a key marker for multidrug-resistant tuberculosis (MDR-TB). Early molecular detection of rifampicin resistance is essential for timely initiation of appropriate therapy and prevention of disease transmission. Objective To determine the prevalence of rpoB gene mutation associated with rifampicin resistance among patients with tuberculosis and to evaluate associated demographic and clinical risk factors in a tertiary care hospital setting. Materials and methods This prospective cross-sectional study was conducted over 18 months (July 2024-January 2026) in the Departments of Microbiology and Pulmonary Medicine at SGRR Institute of Medical and Health Sciences, Dehradun. Seventy patients with microbiologically confirmed tuberculosis were enrolled. Clinical specimens were processed using the N-acetyl-L-cysteine-sodium hydroxide method. Detection of Mycobacterium tuberculosis was performed using the RT-PCR technique with Truenat kit (3B BlackBio Dx, India). DNA extracted using the QIAamp DNA Mini Kit was subjected to allele-specific polymerase chain reaction (PCR) targeting a 531 specific codon of the rpoB gene. Amplified products were analyzed by agarose gel electrophoresis. Statistical analysis was performed using IBM SPSS Statistics version 27.0 (IBM Corp., Armonk, NY, USA), and a p-value <0.05 was considered statistically significant. Results The majority of patients belonged to the 31-45 years age group (24, 34.3%), and males constituted 45 (64.3%) of the study population. Pulmonary tuberculosis accounted for 98.6% of cases. rpoB gene mutations indicative of rifampicin resistance were detected in 5 of 70 patients, yielding a prevalence of 7.1%. All mutation-positive cases were observed among pulmonary TB patients. Although higher proportions of rpoB mutation were noted among previously treated patients (3, 21.4%) (n=14), those with treatment default history (2, 40.0%) (n=5), patients with cavitary disease on chest radiography (4, 21.1%) (n=19), HIV co-infected individuals (1, 16.7%) (n=6), and diabetic patients (2, 11.1%) (n=18). However, none of these associations was statistically significant (p>0.05). Conclusion Rifampicin resistance mediated by rpoB gene mutation was identified in 7.1% of tuberculosis patients in the present study. Higher frequencies among previously treated patients and those with cavitary disease were observed; however, no statistically significant associations with the evaluated risk factors could be deduced. Early molecular detection of rifampicin resistance and focused screening of high-risk groups are crucial for strengthening tuberculosis control and improving clinical outcomes.