A recent study from Uttar Pradesh has cast doubt on the reliability of the conventional smear microscopy test, a cornerstone of India's tuberculosis (TB) diagnosis, revealing it misses a significant number of infections. The research underscores the urgent need to adopt more sensitive, made-in-India molecular tests to meet the country's ambitious goal of eliminating TB.
The Critical Gap in Conventional TB Testing
Dr. Aroop Mohanty, an associate professor in the department of microbiology at AIIMS Gorakhpur, highlighted the findings of a study conducted at a tertiary care hospital in eastern Uttar Pradesh. Published in the International Journal of Mycobacteriology, the research analyzed 4,249 pulmonary and extra-pulmonary samples.
The results were stark. The traditional Ziehl–Neelsen (ZN) smear microscopy method, widely used across India due to its affordability and availability, detected TB in only 4.3% of the cases. In contrast, the TrueNat Mycobacterium tuberculosis (MTB)/rifampicin (RIF) test identified the infection in 13.7% of the samples, demonstrating a vastly superior sensitivity.
Why Smear Microscopy Falls Short
Dr. Mohanty explained the limitations of the older method. "Smear microscopy is affordable and easily available, but its sensitivity is limited, especially in patients with early disease, extra-pulmonary TB, HIV co-infection, or diabetes," he said. Essentially, the test often fails to detect TB in patients with a low bacterial load, allowing the disease to spread undiagnosed.
The TrueNat test, a WHO-endorsed, made-in-India, chip-based real-time PCR test, offers a powerful alternative. It not only detects the TB bacteria rapidly but can also identify rifampicin resistance—a critical piece of information for effective treatment. The study found rifampicin resistance in 5.6% of the confirmed TB cases.
A Path Forward for TB Elimination
Dr. Mohanty emphasized that early detection of such drug resistance is crucial for starting the right treatment promptly and preventing further transmission in the community. He stressed that a combined approach, using conventional microscopy alongside advanced molecular diagnostics like TrueNat, could significantly strengthen TB control efforts, particularly in resource-limited, high-burden regions like eastern Uttar Pradesh.
The study strongly reinforces the argument for expanding access to rapid molecular testing under India's national TB programs. This shift is vital for ensuring timely diagnosis and moving closer to the national goal of TB elimination. Maj Gen Vibha Dutta, executive director and CEO of AIIMS Gorakhpur, congratulated the research team and expressed hope for more such high-quality research to support India's public health missions.
The findings present a clear call to action: to bridge the diagnostic gap and curb the TB epidemic, India must accelerate the integration of accurate, homegrown molecular tests into its healthcare framework.
