A comparative study of CBNAAT and AFB smear for the diagnosis of sputum smear negative pulmonary tuberculosis patients in a tertiary health care centre of Southern Odisha

Nalini Prava Das, Abinash Panda


Background: Pulmonary tuberculosis (PTB) is one of the most common infectious diseases & Continues to be the major health problem even today. Sputum smear negative (SSN) pulmonary tuberculosis is about 40% to 60% of the clinical and radiological suspected cases of pulmonary TB. Establishing early diagnosis and starting treatment early can have significant effect on morbidity and mortality in these patients. Broncho alveolar lavage (BAL) was obtained by fibro optic bronchoscopy (FOB) 
Objectives: Minimising the under and over use of anti-tubercular therapy in diagnosis of pulmonary TB. To compare between the sputum CBNAAT with BAL fluid CBNAAT , compare between sputum CBNAAT with BAL fluid AFB staining, compare between BAL fluid CBNAAT with BAL fluid AFB in diagnosis of
Materials and Methods: 108 SSN patients with clinical and radiological findings of PTB were taken. BY FOB BAL obtained and subjected to CBNAAT. Sputum samples of the above patients were subjected to CBNAAT and compared.
Results: In this study commonest age group was 18 to 39 years;64 patients (59.25%). Males (57.40%) were more in numbers than females (42.59%). In our study, 24(25.92%) were alcoholic and 84 (90.72%) were non alcoholic. 68(73.44%) had co-morbid conditions. Out of them 28 (30.24%) were of obstructive airways disease which was the commonest co-morbidity. BAL CBNAAT Mtb detection was better than BAL AFB smear, sputum CBNAAT was significantly better than BAL AFB smear & BAL CBNAAT was better than sputum CBNAAT.
Conclusion: BAL CBNAAT is useful in the early diagnosis of sputum smear negative pulmonary tuberculosis cases

Keywords: Sputum, Broncho alveolar lavage, CBNAAT, Sputum smear negative,
Fibro optic bronchoscopy.

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