Geographical trends of drug-resistant strains of Mycobacterium leprae in TLM hospitals: insights from a four-year study across eleven hospitals in eight Indian States.

BACKGROUND

Leprosy, caused by Mycobacterium leprae, remains a significant global health concern despite the introduction of the WHO-recommended Multidrug Therapy (MDT). Recent reports of antimicrobial resistance (AMR) to key anti-leprosy drugs, including rifampicin, dapsone, and ofloxacin, have raised concerns about treatment efficacy and disease control.

OBJECTIVE

This study aimed to investigate the geographical distribution of drug-resistant M. leprae strains among leprosy patients in India, including new, reactional, defaulter, and relapse cases, from 2021 to 2025.

METHODS

A cross-sectional study was conducted at 11 hospitals of The Leprosy Mission Trust India (TLMTI) across 8 states of India. Slit-skin smears and biopsies were collected from 3,030 confirmed leprosy cases. DNA was extracted and screened for mutations in the rpoB, folP1, and gyrA genes using PCR and Sanger sequencing, in accordance with WHO guidelines.

RESULTS

We observed overall drug resistance to rifampicin (7.8%), dapsone (5.9%), and ofloxacin (7.0%) in the study. Multidrug resistance was observed in 2.1% of cases. Rifampicin resistance was identified in 11.6% of relapse cases (84/715), 13.8% of defaulter cases (26/188), 7.3% of T2R cases (84/1148), 10.4% of T1R cases (26/249), and 2.4% of newly diagnosed cases (18/730). Rifampicin-resistant strains were observed to be geographically clustered in the districts of Prayagraj, Bokaro, Purulia, and Champa.

CONCLUSION

The detection of primary and secondary drug resistance in new and relapse cases highlights the ongoing transmission of drug- resistant M. leprae strains and challenges to effective case management. These findings highlight the urgent need for expanded AMR surveillance, routine molecular diagnostics, and reinforced adherence to MDT to curb the spread of resistant strains and support India’s leprosy elimination goals.