A comparative study of cartridge-based nucleic acid amplification test and ziehl–Neelsen stain with culture on lowenstein–Jensen media as gold standard for the diagnosis of pulmonary tuberculosis

Abstract

Introduction: Tuberculosis (TB) is an airborne disease caused by Mycobacterium tuberculosis that usually affects the lungs, leading to fever, cough, and chest pain. Although a declining trend was observed in most developed countries, TB remains a leading cause of morbidity and mortality in many developing countries, including India. Materials and Methods: This prospective study was carried out using 150 sputum samples of suspected pulmonary TB patients. All the samples were subjected to Ziehl–Neelsen stain, cartridge-based nucleic acid amplification test (CBNAAT) and culture on Lowenstein–Jensen (LJ) media. They were compared for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in terms of quantitative results. Results: CBNAAT results of the sputum samples showed a sensitivity of 100%, 88.7% specificity, 90.3% PPV, and NPV 94%, whereas culture on LJ media showed a sensitivity, specificity, PPV, and NPV of 68.3%, 100%, 100%, and 73.9%, respectively. Conclusion: Whereas culture remains the gold standard for the diagnosis of TB, CBNAAT has taken over the domain of diagnosis owing to its high sensitivity and rapid turn over time.

Keywords

• acid-fast bacilli
• cartridge-based nucleic acid amplification test
• lowenstein–jensen media
• mycobacterium tuberculosis