Thitta Mohanty1, Santosh Kumar Panigrahi2, Manoranjan Pattnaik3, Geetanjali Panda4, Deepwanweta Routray5, Jeetendra Kumar Patra6, Bijaya Kumar Meher7
BACKGROUND
Tuberculosis, an important preventable and treatable cause of death is a major health problem worldwide. However, in patients with a compatible clinical picture, sputum smear don’t reveal acid-fast bacilli in all patients. So, alternative methods of obtaining sputum specimen are frequently needed in these patients. Rapid diagnosis of tuberculosis and detection of rifampicin (RIF) resistance are essential for effective disease management. CBNAAT (cartridge based nucleic acid amplification test) (DS Sowjanya, et al)1 is a novel integrated diagnostic device for diagnosis of tuberculosis and rapid detection of RIF resistance in clinical specimen.
The aim of the study is to study different diagnostic modalities in sputum smear negative patients with special reference to CBNAAT.
MATERIALS AND METHODS
This was an observational study done in the Department of Pulmonary Medicine, SCBMCH, Cuttack. 100 patients were selected for the study. In all patients, induced sputum was sent for smear acid-fast bacilli. Those patients whose induced sputum was negative were undergone bronchoscopy for BAL (bronchoalveolar lavage). The specimen was sent for smear acid-fast bacilli, sputum CBNAAT and culture for Mycobacterium tuberculosis.
RESULTS
Total 100 patients, 74 males and 26 females. SI sputum smear positive 29 out of 100. SI CBNAAT positive 23 (32%), BAL CBNAAT yield 38/71 (54%), BAL culture reference standard yield 42/71(59%). Sensitivity, specificity, PPV, NPV, SI CBNAAT 61.9%, 96.5%, 96.3%, 63.6%, respectively. BAL CBNAAT sensitivity, specificity, PPV and NPV 88.09%, 96.5%, 97.36%, 84.84%, respectively. Kappa (Anthony J Viera, et al)2 score 0.808 (substantial agreement).
CONCLUSION
Sputum induction procedure is simple, relatively safe, cost effective and is widely available. Therefore, in a patient with a suspected sputum smear, negative pulmonary tuberculosis sputum induction should be the initial procedure of choice reserving bronchoscopy for the non-responders.
