Laboratory Diagnosis of Tuberculosis: Comparative Evaluation of Traditional and Molecular Methods

By Rahul Eshi1*, Rahul Patil2, Laxmi Tadavi1, Komal Khedkar3

1P.G. College of Pharmaceutical Science and Research, Nandurbar (MS), India
2NTVS Institute of Pharmacy, Nandurbar (MS), India
3Ahinsa Institute of Pharmacy, Dondaicha, Maharashtra, India

Published: April 2026 | DOI: 10.5281/zenodo.19843520 | Download PDF

Abstract

Tuberculosis (TB) remains a major global health concern requiring early and accurate diagnosis for effective treatment and prevention of transmission. Traditional diagnostic methods such as sputum smear microscopy, culture, and histopathology are widely used but have limitations in sensitivity and turnaround time. Advanced molecular techniques including CBNAAT, Truenat, line probe assays, and whole genome sequencing offer rapid and precise detection, including identification of drug resistance. A combined diagnostic approach is essential to optimize patient outcomes.

Keywords:

Tuberculosis, laboratory diagnosis, molecular diagnostics, sputum microscopy, drug resistance

Introduction

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, primarily affecting the lungs. It is transmitted through airborne droplets and remains a major public health issue worldwide, particularly in developing countries. Laboratory diagnosis is essential for confirming infection, guiding treatment, and monitoring response.

Pathophysiology of Tuberculosis

Infection begins when inhaled bacilli reach the alveoli and are phagocytosed by macrophages. The bacteria evade destruction and replicate intracellularly. The immune response leads to granuloma formation, which contains the infection but may allow latent persistence or progression to active disease.

Morphology of Tuberculosis

TB is characterized by granulomatous inflammation with caseous necrosis. Grossly, primary TB forms a Ghon focus, while secondary TB shows cavitary lesions. Microscopically, granulomas consist of epithelioid cells, lymphocytes, and Langhans giant cells.

Clinical Features and Diagnosis

Pulmonary TB presents with chronic cough, fever, night sweats, weight loss, and hemoptysis. Diagnosis involves clinical evaluation, imaging, and laboratory tests including sputum microscopy, culture, and molecular methods.

Laboratory Methods and Comparative Evaluation

Traditional Methods

Sputum smear microscopy using Ziehl-Neelsen staining is rapid and cost-effective but has low sensitivity. Culture techniques are highly sensitive and considered the gold standard but require several weeks for results.

Molecular Methods

CBNAAT provides rapid detection of TB and rifampicin resistance. Truenat offers portability for rural settings, while line probe assays and whole genome sequencing identify drug resistance with high accuracy.

Prevention and Public Health

Prevention strategies include vaccination (BCG), early diagnosis, and treatment of latent infection. Laboratory diagnostics play a key role in surveillance and control programs.

Conclusion

Both traditional and molecular diagnostic methods are essential for effective TB management. A combined approach improves diagnostic accuracy, enables early detection of drug resistance, and enhances patient outcomes.

References

  1. Mohammadnabi N. TB pathogenesis.
  2. Zhang SX. Global TB burden.
  3. Shah H. TB elimination strategies.
  4. Additional references as per original article.