Comparative study between CBNAAT and acid-fast bacilli culture in extra pulmonary tuberculosis

Abstract

Introduction: Mycobacterium Tuberculosis is a complex organism in which lungs are the main portal of infection. Tuberculosis affecting organs other than lungs called as extrapulmonary tuberculosis. Tuberculous lymphadenitis is the most common form of Extrapulmonary Tuberculosis contributing to 35 percent of Extrapulmonary Tuberculosis cases. CBNAAT is a cartridge based nucleic acid amplification test which detects the presence of Mycobacterium Tuberculosis as well as Rifampicin resistance. Materials and Methodology: Samples were collected from the appropriate extrapulmonary sites which included Lymph Node aspirate, Pleural fluid, Ascitic fluid, Abscess, Cerebrospinal Fluid. The samples were sent for AFB smear, CBNAAT and AFB culture. The data was analyzed and results were compared. Results: This cross-sectional study was conducted in a sample size of 89 patients attending the outpatient department in a tertiary care center in the Department of Respiratory Medicine at Santosh Hospital, Ghaziabad who were clinically suspected cases of Extra Pulmonary Tuberculosis. MTB was detected in CBNAAT in 33(37%) cases giving a Yield of 37% with RIF resistance in 2(2.2%) cases and MTB was detected in 53(59.5%) giving it a yield of 59.5% with RIF resistance in 2. Conclusion: There was statistically significant weak agreement seen between CBNAAT finding and AFB culture finding (Kappa value = 0.48; p value <0.01).