To compare the diagnostic accuracy of acid fast bacilli smear results of induced sputum with broncho-alveolar lavage among pulmonary tuberculosis cases keeping acid fast bacilli culture as gold standard in a resource limited setting in non expectorating patients

Abstract

OBJECTIVE: To compare the diagnostic accuracy of acid fast bacilli smear results of induced sputum with broncho-alveolar lavage among pulmonary tuberculosis cases keeping acid fast bacilli culture as gold standard in a resource limited setting in non expectorating patients.

SUBJECTS & METHODS: This cross sectional study was conducted from 14 December2013 to 13 June 2014 in the Department of Thoracic Medicine JPMC Karachi. Patients 18-55 years of age of either gender suspected of pulmonary tuberculosis, unable to produce sputum were enrolled .A total of 84 patients were included in the study. On day one sputum specimen was obtained by inducing sputum. Bronchoscopy was carried out on the other day to obtain of boncho-alveolar fluid. Both samples were sent for AFB smear through Ziehl-Neelsen staining and AFB culture through Lowenstein-Jensen medium.

RESULTS: Diagnostic accuracy of induced sputum AFB smear was found to be 92.85%, sensitivity 63.63%, specificity 97.26%, PPV 77.78% and NPV 95.67% (p-value <0.001)and that of BAL was found to be 86.90%, sensitivity 52.94%, specificity 95.52%, PPV 75% and NPV 88.89% (p-value <0.001).

CONCLUSION: Induced sputum is non inferior ,less expensive and noninvasive in comparison to BAL so it can be used as a diagnostic tool in non expectorating Tuberculosis Suspects.