Clinical characteristics of nontuberculous mycobacterial infections among people with presumptive tuberculosis in India: a multicenter study (2021–2025)

Background Disease caused by nontuberculous mycobacteria (NTM) is often misdiagnosed as tuberculosis (TB) in India. Comprehensive studies on NTM are lacking, therefore, the present study aimed to describe clinical features, underlying conditions, species distribution, and treatment outcomes of NTM disease among people with presumptive TB (individuals with symptoms suggestive of TB) in India. Methods This prospective study (2021–2025) was conducted across seven tertiary care centres in India. People older than or equal to 12 years, irrespective of their human immunodeficiency virus status, diagnosed with NTM disease were included. Individuals with concurrent TB were excluded. Participants were recruited consecutively from individuals with presumptive pulmonary TB (PTB) and extrapulmonary TB at participating centres. Clinical, radiological, and laboratory data were collected from study centres under supervision of dedicated clinicians. Line probe assay (LPA) and Whole-genome sequencing (WGS) were used for NTM diagnosis. Recent guideline-based treatment (GBT) was administered to people diagnosed with NTM disease. Main outcomes of this study included clinical and radiological characteristics, species distribution, and treatment outcomes of NTM pulmonary disease (NTM-PD) and extrapulmonary NTM (EP-NTM) disease. Findings Among 71,143 individuals with presumptive TB, 230 (0·32%) had NTM disease (191 pulmonary and 39 extrapulmonary). In NTM-PD, common underlying conditions included previous PTB (80·6%), malnutrition (47·1%), and vitamin D deficiency (43·5%). M. avium complex (25·7%), M. abscessus complex (24·3%), and M. kansasii (20·9%) were the most frequently isolated NTM species. LPA and WGS showed 97·6% concordance in diagnosing NTM. Of 155 individuals with NTM disease with complete treatment details, 137 (88·4%) completed therapy; mean culture conversion time was 94·3 days for NTM-PD. Poor treatment outcome (9 deaths, 9 lost to follow-up) was noted in 18/155 (11·6%) treated individuals. Interpretation NTM disease among people with presumptive TB is an emerging public health problem in India. Integrating rapid molecular diagnostic tests for early diagnosis and GBT into National Tuberculosis Programmes is essential to improve outcomes by reducing diagnostic and treatment delays. Funding Indian Council of Medical Research.