YIELD OF INDUCED SPUTUM IN CLINICALLY DIAGNOSED PULMONARY TUBERCULOSIS

Background:- Direct sputum smear examination is used as a basic diagnostic tool in the diagnosis of pulmonary tuberculosis. But difficulty in obtaining adequate sputum is the main cause of failure of bacteriological diagnosis. Alternative methods of obtaining sputum specimens are frequently needed in those patients with clinicoradiological suspicion of TB who are unable to expectorate or are smear negative. Aim:- To assess the yield of smear positivity of induced sputum (SI) with hypertonic saline nebulisation, broncho-alveolar lavage fluid and Rifampicin resistance in clinically diagnosed pulmonary TB who have no/inadequate sputum. Materials and Methods:- In the present cross-sectional observational study, we analysed the smear positivity of AFB in induced sputum of patients at Veer Surendra Sai Institute of Medical Science & Research, Burla, Odisha, India, from November 2018 to October 2020. A total of 100 patients with clinically diagnosed pulmonary TB who were unable to produce adequate sputum fulfilling inclusion criteria were included in the study. 10 ml of 3% hypertonic saline was injected into the nebulizer reservoir device. The assembly was connected to the jet nebulizer. The patients were instructed to inhale and exhale the mist of the nebulized solution through the mouth piece only. The inhalation of hypertonic saline was interrupted every 5 min, so that the patient could expectorate the sputum into a clean sterile sputum container. The sputum samples were stained with auramin-rhodamin stain and examined for AFB, also same samples were subjected for CBNAAT(cartridge based nucleic acid amplification test). Selected sputum induction(SI) CBNAAT negative patients are also underwent bronchoscopy and BAL fluid was subjected for CBNAAT. Results:- Out of 100 clinically diagnosed tuberculosis patients, 49% of cases had only infiltration, 45% cases had consolidation,17% had infiltration with fibrosis,16% cases with cavitary lesions and 6% had miliary lesions in chest X -ray. 17(17%) cases became induced sputum smear positive, 30(30%) cases became induced sputum CBNAAT positive. All induced sputum CBNAAT positive cases were rifampicin sensitive. No rifampicin resistance was detected. Out of 70 patients with SI CBNAAT negative, 21 patients with highly clinico radiological suspicion underwent bronchoscopy and 4(19%) patients become post bronchoscopy sputum AFB positive. Out 21 patients 8(38%) patients become BAL CBNAAT positive and all are rifampicine sensitive. Conclusion:- Induced sputum and BAL fluid are better alternative methods for diagnosis in patients with clinico-radiological suspicion of TB who are unable to expectorate or are smear negative and no rifampicin resistant cases were detected throughout this study.