Assessment of rapid bedside point of care diagnostic utility of cartridge-based nucleic acid amplification test (CBNAAT) in the diagno

Background: Extrapulmonary tuberculosis poses a great challenge in the diagnosis and management due to the paucibacillary nature of the disease and limited tests available for early diagnosis. Tuberculous lymphadenopathy is the most common extrapulmonary manifestation of tuberculosis (TB). The Xpert mycobacterium tuberculosis/rifampicin (MTB/RIF) assay or cartridge-based nucleic acid amplification test (CBNAAT) for Mycobacterium is a rapid, automated, molecular assay, along with bedside fine needle aspiration cytology (FNAC) of the lymph nodes, together can form an excellent early screening tool for diagnosis and treatment initiation for TB. Aim: To assess the early and rapid diagnostic accuracy of CBNAAT in the diagnosis of TB lymphadenitis by bedside FNAC procedure at a rural center. Methodology: This prospective observational diagnostic accuracy study [FNAC-Fine needle Aspiration Smear for Tuberculosis (FAST)] was conducted from January 2024 to June 2025 among 61 patients clinically suspected of lymph node TB. Bedside FNAC was performed on lymph nodes from the neck, axilla, or inguinal regions. Samples were tested using CBNAAT, liquid culture via BACTEC MGIT 960, and acid-fast bacilli (AFB) staining with Ziehl-Neelsen and Auramine methods. Mycobacterial culture served as the reference standard for comparison. Results: Most patients were young adults (20–40 years, 65.6%) with a female predominance (67.2%). CBNAAT was positive in 62.3% of cases, while culture confirmed TB in 47.5% of cases. Granulomatous lymphadenitis was observed in 83.6% of cases, with 72.5% CBNAAT positivity and 6.5% rifampicin resistance among these. Reactive lymphadenitis cases were mostly negative on culture and CBNAAT. AFB staining detected only 20% of cases. Conclusion: CBNAAT performed on FNAC samples shows excellent sensitivity and provides rapid results for diagnosing tuberculous lymphadenitis, while also identifying rifampicin resistance. This makes it an ideal point-of-care test for early treatment initiation, especially in resource-limited settings.