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Research Paper | Medical Microbiology | India | Volume 12 Issue 5, May 2023

A Comparative Study of different Diagnostic Modalities, ZN Stain, Culture and TrueNat for the detection of Pulmonary TB in Sputum Sample and To Study their Co - infection with HIV at a Tertiary Care Hospital

Arpita Kushwaha | Dr. R. Sujatha

Abstract: Introduction: Tuberculosis is an airborne disease caused by Mycobacterium tuberculosis (MTB) that usually affects the lungs. People having HIV infection are 15 - 22 times more likely to develop active TB. For diagnosis of TB, Sputum smear microscopy with ZN staining is the most commonly used test but it has low sensitivity, while culture on LJ media remains the gold standard is time consuming and require special procedure to give positive results. On the other side faster and simple Nucleic Acid Amplification Technique (TrueNaT) due to its rapidity and sensitivity not only help in early diagnosis of TB especially in HIV patients but also detects drug resistance TB. Aim: To evaluate the sensitivity, specificity, positive predictive value and negative predictive value of smear examination, LJ culture and TrueNat with sputum sample in patients with suspected pulmonary tuberculosis and comparison of all three different techniques and to screening the patients for Co - infection of HIV. Material and Methods: This prospective study was carried out using 100 sputum samples of suspected pulmonary TB patients. All the samples were subjected to ZN stain, LJ culture and TrueNat test. For HIV testing by rapid card, One 5 mL blood sample from confirmed TB patients have taken and processed according to the guidelines of National Aids Control Organization (NACO). Results: Out of 100 sputum samples, 36 (36%) patients were positive by ZN stain, 53 (53%) by LJ culture and 60 (60%) as per TrueNat. Sensitivity, specificity, PPV and NPV of LJ culture were 62.2%, 100%, 100% and 70.1%, respectively. Whereas ZN stain showed the sensitivity, specificity, PPV and NPV of 83.3%, 100%, 100% and 91.4%, respectively. In the case of TrueNat the sensitivity, specificity, PPV and NPV were 91%, 100%, 100% and 88%, respectively. Out of 100 patients 6 were HIV reactive and 10 patients were MDR detected by TrueNaT. Conclusion: In our study, ZN stain is rapid and inexpensive and it is better than LJ culture, while the sensitivity of TrueNat is much higher than the ZN stain and culture. So TrueNat is best tool for the early diagnosis of TB and simultaneously detect Rifampicin resistance.

Keywords: Mycobacterium tuberculosis, Sputum, Smear microscopy, LJ Culture, TrueNat

Edition: Volume 12 Issue 5, May 2023,

Pages: 1706 - 1711