To Study the Usefulness of Cartridge Based Nuclear Acid Amplification Test [CBNAAT] in Bronchoalveolar Samples in the Diagnosis of Sputum Negative Patients with Presumptive Pulmonary Tuberculosis

Background: 40-60% of patients with presumptive PTB may fail to produce sputum, or when it is available, AFB/CBNAAT may be negative on repeated smear examination. These patients can be diagnosed by flexible fibreoptic bronchoscopy. Aims: This study was carried out to know the usefulness of bronchoscopy in sputum negative suspected pulmonary tuberculosis patients. Material and method: We identified 68 consecutive cases of suspected pulmonary TB between Nov 2016 and July 2017, who had negative results on sputum smears examination by fluorescent microscopy/ZN staining on at least 2 samples or CBNAAT and did fibre optic bronchoscopy and sent bronchial aspirate for CBNAAT and AFB staining. Result: Males constituted majority of our study population. The most common age group involved in the study was less than 30 years (35.2%). Cough was the most common symptom reported by 45 patients (66.1%). The past history of PTB was present 13 patients (19.1%). 27.9% of study population had consolidation on CXR. Out of 68 clinically suspected sputum negative-PTB patients, 32 patients (47%) were finally diagnosed as having microbiologically confirmed PTB. Conclusion: CBNAAT done on bronchial aspirate can be an important adjunct to bacteriological confirmation of suspected cases who were otherwise sputum negative or not expectorating adequate sputum.