A Comparative Study between Conventional Microscopic Examination and Truenat Test with Cartridge-based Nucleic Acid Amplification Test Method for Detection of Pulmonary Tuberculosis

Background and Objectives: Pulmonary tuberculosis (TB) is still a major cause of infectious disease associated with higher mortality and morbidity in India. It can be prevented by early detection and initiation of early treatment. The present study aims to evaluate and compare sputum microscopic detection of Acid-fast bacilli by Ziehl–Neelsen (ZN) staining with the Truenat Real Time mini-polymerase chain reaction (PCR) system and existing molecular detection method cartridge-based nucleic acid amplification test (CBNAAT). The goal of the current study is to improve case detection by using three parallel test methods to see the efficacy of each method and providing rapid and accurate diagnostic results for the detection of Mycobacterium tuberculosis (MTB). Materials and Methods: This prospective study was carried out using sputum samples of suspected cases of pulmonary TB. One is the conventional gold standard method, sputum microscopic examination by ZN stain, and other is the rapid mini real-time PCR Truenat MTB/rifampicin (RIF) test, and further confirmation with the CBNAAT method. Results: We compare the percentages of positivity for detection of pulmonary TB by sputum microscopy, Truenat and CBNAAT test (considered as a gold standard rapid molecular detection test). Out of 219 samples, 27 samples (12.3%) were confirmed positive. Out of 27 confirmed positive cases detected by CBNAAT, with Truenat test, 24 cases (89%) were also detected positive, and 17 cases (63%) were positive by sputum microscopic examination by ZN stain. Truenat MTB/RIF and CBNAAT showing drug resistance pattern to RIF. RIF resistance was found in 4 (16.6%) of patients, out of which 2 samples (8.3%) found intermediate resistance in cases with the Truenat MTB/RIF test. Whereas it was detected in 4 (14.8%) by CBNAAT method. Conclusion: In this study, sensitivity of Truenat test is much higher than the ZN stain microscopic examination and almost equal to GeneXpert CBNAAT test. Each test gives a rapid result within 2 h. About detection of resistance pattern to RIF Truenat was more sensitive than CBNAAT, which was a very suggestive finding in this study. Due to higher sensitivity and detect drug resistance patterns to RIF, Truenat MTB/RIF serves as an important diagnostic tool in the detection of MTB in resource-limited peripheral laboratories.