Role of cbnaat (cartridge based nucleic acid amplification test) in the diagnosis of tubercular pleural effusion

Introduction: Tuberculosis (TB) has existed for millennia and remains a major global health problem. Among extra-pulmonary tuberculosis, lymph node tuberculosis is the most common type constitutes about 35%cases followed by pleural effusion (20%), bone and joint (10%), genitourinary TB (9%), TBM (5%), other (13%). Cartridge based nucleic acid amplification test (CBNAAT), specific for Mycobacterium tuberculosis has been recently introduced for detection of tubercular pleural effusion. It has an added advantage of detecting rifampicin resistance. Material and methods: With an aim to determine the role of pleural fluid CBNAAT in tubercular pleural effusion, the study was conducted in department of Internal medicine, R.N.T. Medical College Udaipur, Rajasthan. Patients with symptoms suggestive of pleural effusion were enrolled. Pleural fluid was drawn using standard procedure protocol and sent for CBNAAT test and routine as well as bacteriological examination. Results: 200 patients were included, with male to female ratio of 3.5:1. The most common affected age group was below 45 years and mostly from rural area (84%). 114 (57%) of 200 patients were underweight. Mostly were farmers and most were smoker. Most common morbidity was DM followed by COPD, HTN and HIV. In our study, most common symptom was chest pain. 52 patients had pulmonary involvement and 28 were sputum AFB positive. Pleural fluid CBNAAT was positive in 37 patients out of which 31 were sensitive to rifampicin. Conclusion: While the cytology of Pleural Fluid gives a very good estimation of the positivity status of a patient than CBNAAT as the higher cell count is suggestive of TB but NAAT helps in diagnosing both the positivity status as well as rifampicin resistant state of the patient. To conclude, CBNAAT has the potential to significantly improve and escalate the diagnosis of pleural fluid specimens at both hospitals as well as point-of-care settings in regions not only with high TB burden but also with overlapping HIV. Also, detection of Rifampicin resistance aids in prompt initiation of appropriate therapy and thus improving the overall quality of TB care.