Comparison of Ziehl-Neelsen's stain, fluorescent stain with CBNAAT of sputum for the diagnosis of pulmonary tuberculosis

Abstract

Introduction: Pulmonary tuberculosis remains one of the most dangerous communicable diseases. More than two billion people are estimated to be infected with Mycobacterium tuberculosis. In 2017, approximately 10 million individuals became ill with tuberculosis,among them 2.79 million individuals were active cases, 1.6 million died among which 0.3 million died with coexistent HIV infection. Prompt diagnosis of active tuberculosis facilitates timely therapeutic intervention and minimize the community transmission. As tuberculosis is a global problem, for eradication of the disease, early diagnosis, timely identification and improved detection is essential. The diagnosis of tuberculosis is challenging in cases of insufficient sputum and paucity of bacilli. With this background, this study was planned to compare Ziehl-Neelsen's stain, Fluorescent stain and CBNAAT (Cartridge based nucleic acid amplification test) as per RNTCP guidelines. Material and Methods: A prospective interventional study was carried out using 188 sputum samples of suspected pulmonary tuberculosis. All 188 samples were subjected to three methods Ziehl-Neelsen's stain, fluorescent stain and CBNAAT. They were compared for sensitivity and specificity in terms of qualitative results. The data recorded was then analyzed statistically. Results: In our study out of 188 cases 124 were males, 64 were females. Out of 188 samples, the smear positivity rate of ZN stain was 33.5%, fluorescent stain was 40.9%, and the positivity rate of CBNAAT was 51.1%. Conclusion: CBNAAT is more sensitive and specific in detection of pulmonary TB. An additional feature of rifampicin resistance can also be detected by CBNAAT.

Keywords

• acid fast bacilli
• cbnaat
• fluorescent stain
• pulmonary tuberculosis
• ziehl-neelsen stain