Drug resistance in patients with tuberculosis: a study from a tertiary care center in northern India

Tuberculosis (TB) continues to be a major global health challenge, with India contributing a significant share of the burden. Drug-resistant TB (DR-TB) is additionally responsible for the huge numbers. Despite the magnitude of the problem, there is a relative paucity of data with respect to the different patterns of DR-TB from Northern India. A retrospective, observational study was undertaken at the Department of Pulmonary Medicine at Chest and TB Hospital, Government Medical College, Patiala, Punjab, India, to analyze the drug resistance profile of Mycobacterium tuberculosis and associated risk factors, essential for aiding clinicians and evaluating evidence to strengthen programmatic strategies, with an aim to ultimately reduce the overall burden of TB. A total of 14,142 microbiologically confirmed M. tuberculosis cases from 2022-2024 were reviewed. Resistance patterns were characterized according to national guidelines. The prevalence of resistance patterns and associations between drug resistance and demographic variables, treatment and contact history, and comorbidities (HIV co-infection, diabetes mellitus, alcohol, and smoking) were analyzed using chi-square tests and univariate and multivariate logistic regression. In this cohort, the median age of included patients was 37 years, with the majority from 21-40 years (41.01%) and predominantly male gender (60.72%). The overall prevalence of DR-TB was 8.6%. INH monoresistance accounted for 50.53% of DR-TB, with 35.99% harboring katG and 14.54% inhA gene mutations. katG mutations were significantly higher in newly diagnosed patients (37.7%, p=0.006), those with a positive contact history (37.6%, p=0.027), diabetics (43.6%, p=0.038), and individuals with tobacco exposure (49.1%, p=0.034). inhA mutations were strongly associated with HIV co-infection (32.30%, p=0.005). Rifampicin resistance was more frequent among previously treated cases (15.3%, p<0.001), patients with no contact history (13%, p=0.003), and those with HIV co-infection (19.40%, p=0.026). Multivariate analysis demonstrated that female gender [adjusted odds ratio (AOR) 1.15, p=0.030], previous treatment history (AOR 1.78, p<0.001), and absence of contact history (AOR 1.74, p<0.001) had higher odds of having DR-TB. These findings, when interpreted in the context of existing literature, suggest that factors contributing to the development of resistance are either acquired through treatment failure or community transmission. Individual host factors, including gender and the presence of comorbidities such as HIV, diabetes, and tobacco exposure, further increase the risk. Understanding the epidemiology of drug resistance is crucial to improve patient outcomes, curb the burden of TB in our region, and eventually advance the nation's TB elimination goals.