A Study of the Diagnostic Utility of Cartridge Based Nucleic Acid Amplification Test of Various Body Fluids Other Than Sputum in Different Forms of Tuberculosis

Abstract

Introduction: Diagnosis of TB is difficult in specimens having low number of bacilli. In recent times, CBNAAT is used due to its rapidity, sensitivity and specificity The heterogeneous clinical presentations, pauci-bacillary nature and difficulty in obtaining specimens (often requiring invasive procedures) make the diagnosis of TB, a challenging task and hence the requirement for a rapid, simplified and cost effective diagnostic tool arises. Objectives: To determine the sensitivity, specificity, positive predictive value and negative predictive value of CBNAAT for diagnosis of Tuberculosis from specimens other than sputum. Methodology: Study Design-Longitudinal prospective study, Duration of Study-1 year study period, Study Setting -RNTCP Cell in the Department of Respiratory Medicine, MMCHRI, Sample Size-60, Study Population-Sputum Negative Presumptive Pulmonary and Extra pulmonary Tuberculosis Patients, Sample Collection- BAL, Pleural Fluid, Pus Aspirate, CSF, Lymph Node aspirate, Ascitic Fluid, Gastric Aspirate, Synovial Fluid. Results: In our study Majority of study population were in the age group of Less than 30(30%). About 25% were in the age group of more than 61 years. Nearly 12% were in the age group of 41-50 years. About 15% were in the age group of 31-40 years. Nearly 18% were in the age group of 51-60 years. In our study 63% were males and 37% were females. In our study 40% are smokers and 60% are nonsmokers. In our study 27% are diabetics and 73% are non-diabetics. In our study 3.4% had HIV and 96.6% are HIV negative. 10% of study population had previously taken ATT and 90% had not taken ATT. About 25% tested positive for CBNAAT test and 75% tested negative for the test. Conclusion: The diagnosis of Tuberculosis remains challenging since the number of M.tb bacilli present in tissue at the site of disease is often low and clinical specimen from deep seated organs may be difficult to obtain. CBNAAT provides an edge over other methods by reducing the time required for diagnosis and precision in detection of M.tb bacilli not only in sputum samples but also in extra-pulmonary specimens.