Chandigarh: PGI develops TB-detection kits with higher sensitivity

Naina Mishra

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Chandigarh, February 4

The Postgraduate Institute of Medical Education and Research (PGI) has developed state-of-the-art bio-safe filter paper-based kits for the detection of tuberculosis (TB) and drug resistance. This breakthrough is poised to transform TB diagnosis, especially in resource-constrained settings, where millions of cases go undetected.

TB remains a global health concern, with 10.6 million new cases and 1.4 million deaths reported in 2021. The large number of cases that are missed in diagnosis and the alarming increase in drug-resistant TB infection has created a critical need for near-patient and cost-effective technologies that can rapidly detect mycobacterium tuberculosis (M. tuberculosis) and associated drug resistance. Shockingly, 4 million cases were missed due to a lack of proper diagnosis.

Scores over conventional method

• Bio safe: Disinfection up to 8-log of M. Tuberculosis in spiked sputum
• Sensitive: Better sensitivity than existing smear tests (100 bacteria/ml)
• Stable transport: DNA stable at 50 degrees up to 4 weeks on trans-filter
• High quality DNA: Isolated DNA was amenable for molecular testing
• Higher positivity: Better results were obtained by TB Detect kit against conventional smear microscopy (4-7% positivity increment)

The conventional method, direct smear microscopy, despite its low sensitivity, is the primary diagnostic tool used in primary healthcare settings. Despite the low and variable sensitivity of direct smear microscopy that ranges between 20 per cent and 60 per cent, this technique is the most frequently used diagnostic test for pulmonary TB in peripheral or primary healthcare centres.

The PGIMER created and tested three kits: TB Detect (with biofm-filter device), TB Concentration and Transport (with trans-filter device), and TB DNA Extraction kits. These kits collectively contribute to improving the efficiency and safety of TB diagnosis and analysis at primary healthcare centres and central laboratories. They enable better sample concentration, transport, and advanced molecular testing for more accurate and timely detection of TB and its drug-resistant forms.

During the phase 1 i.e. “development of bio-safe kits (2015-2017), the PGI developed kits that ensure bio-safety by disinfecting M. tuberculosis in spiked sputum. These kits demonstrated improved sensitivity, detecting as low as 100 bacteria/ml, surpassing the conventional smear tests. Higher positivity was obtained for TB Detect kit in comparison to conventional smear microscopy i.e. 4 to 7 per cent increment.

In the phase II, “multi-centric validation (2018-2019)”, the ICMR funded the multi-centric validation, confirming the bio-safety and efficiency of the kits at six sites. The TB Detect kit exhibited an impressive 99.95 per cent efficiency in sputum disinfection. Positive findings led to the endorsement of the kits for evaluation under the National Tuberculosis Elimination Programme.

In the phase III of operational feasibility study (2022-2023), the ICMR approved and recommended the kits for integration into the National Tuberculosis Elimination Programme. The kits received the green light for use in 23,038 designated microscopy centres, aiming to enhance TB diagnosis at peripheral healthcare centres.

The kits are expected to bridge the diagnostic gap, improving TB control in communities and preventing the missed millions.