Drug-resistant tuberculosis in Nepal: the sixth national prevalence drug-resistant survey, 2024

Abstract

Tuberculosis (TB) remains a major public health challenge in Nepal, characterized by increasing drug-resistant TB (DR-TB) and constrained surveillance capacity. The sixth national DR-TB prevalence survey was therefore implemented to address this gap. This study aimed to estimate the national prevalence of DR-TB and identify risk factors among new and previously treated pulmonary TB patients. A national cross-sectional survey was conducted from December 2022 to January 2024, enrolling bacteriologically confirmed pulmonary TB patients using stratified cluster sampling at 49 diagnostic centers. Phenotypic and genotypic drug sensitivity testing was performed on 1768 Mycobacterium tuberculosis-confirmed samples. Logistic regression analysis estimated DR-TB prevalence and its associated risk factors. Rifampicin resistance was identified in 2.2% [95% confidence interval (CI) 1.4–3.6] of new TB patients and 10.1% (95% CI 5.1–19) of previously treated patients. In total, 9.4% exhibited resistance to at least one first-line drug, with isoniazid exhibiting the highest resistance rate. Within the rifampicin-resistant TB (RR-TB) group, resistance to moxifloxacin was more prevalent among newly diagnosed patients than previously treated patients at both critical concentrations (55.3% vs. 33.3% at 0.25 µg/ml; 34.2% vs. 11.1% at 1 µg/ml). Previous TB treatment emerged as the strongest predictor of rifampicin resistance [adjusted odds ratio (aOR) = 4.1, 95% CI 2.6–6.4]. The prevalence of RR/multidrug-resistant (MDR)-TB in Nepal remains stable compared with previous surveys. However, a high rate of fluoroquinolone resistance among new patients underscores the urgent need for improved antibiotic stewardship and expanded drug-susceptibility testing services. These findings provide essential evidence to guide national TB control strategies. Nepal’s rifampicin-resistant and multidrug-resistant TB prevalence remains stable compared with previous national surveys, indicating sustained effectiveness of TB treatment and control strategies. Previous TB treatment is the strongest risk factor for rifampicin resistance, underscoring the importance of treatment adherence, follow-up, and early drug susceptibility testing. High fluoroquinolone resistance, specifically among new RR-TB patients, is a growing concern, with implications for the effectiveness of WHO-recommended MDR-TB regimens. Expanded access to drug susceptibility testing and strengthened antimicrobial stewardship are urgently needed to guide appropriate treatment and prevent further resistance. Nepal’s rifampicin-resistant and multidrug-resistant TB prevalence remains stable compared with previous national surveys, indicating sustained effectiveness of TB treatment and control strategies. Previous TB treatment is the strongest risk factor for rifampicin resistance, underscoring the importance of treatment adherence, follow-up, and early drug susceptibility testing. High fluoroquinolone resistance, specifically among new RR-TB patients, is a growing concern, with implications for the effectiveness of WHO-recommended MDR-TB regimens. Expanded access to drug susceptibility testing and strengthened antimicrobial stewardship are urgently needed to guide appropriate treatment and prevent further resistance.