Performance of Molecular Diagnostics in Strengthening Tuberculosis Detection and Drug Resistance Surveillance: A Comparative Study with Conventional Methods
Nithya S. Roy, Kiran Bala, Tamanna Bordoloi, Prayas Sethi, Vivek Shankar, Anant Mohan, Urvashi B. SinghBackground:
Tuberculosis (TB) remains a major public health challenge, with India bearing the largest global burden. Rapid molecular diagnostics such as GeneXpert
Methods:
A 16-month retrospective observational study (January 2024–April 2025) at a tertiary care hospital in New Delhi analyzed 9468 clinical specimens. Theis was to compare the diagnostic performance of molecular methods such as GeneXpert MTB/RIF, Truenat MTB/MTB Plus, and FL-LPA with ZN smear microscopy and MGIT culture for pulmonary and extrapulmonary TB, and to assess RIF resistance detection. All samples underwent ZN smear, MGIT culture, and molecular testing. Nucleic acid amplification test (NAAT)- positive samples were subjected to FL-LPA for resistance profiling.
Results:
Out of 9468 clinical specimens analyzed, MTB was detected in 989 (10.45%) cases. Positivity was slightly higher in pulmonary samples (11.4%) compared to extrapulmonary samples (9.5%). RIF resistance was identified in 61 (6.2%) cases, whereas 36 (3.64%) results were indeterminate, most of which occurred in specimens with very low bacillary load. ZN smear microscopy detected only 19.11% of NAAT-positive samples, and smear positivity increased significantly with increasing bacterial load (
Conclusion:
GeneXpert MTB/RIF and Truenat MTB Plus outperform smear microscopy and MGIT in sensitivity, particularly for low-bacillary load. FL-LPA enhances resistance detection, identifying additional RIF-resistant cases missed by NAAT. Incorporating NAAT as the frontline diagnostic, complemented by LPA and culture, can strengthen TB detection and drug resistance surveillance in high-burden settings.