Evaluation of BAL versus sputum specimen for the diagnosis of pulmonary tuberculosis in sputum AFB smear negative patients- retrospective study at PIMSR, Gujarat

Abstract

Aims and Objective: Early diagnosis of smear negative tuberculosis is a significant challenge in control of tuberculosis. The present retrospective study was done on sputum and BAL samples of the same patients for better diagnosis of pulmonary tuberculosis. Material and Methods: A total of 1000 (700 sputum and 300 BAL) specimens were processed to rule out tuberculosis in suspected cases during the period of August 2015 to March 2018. The result of sputum as well as BAL specimens from 300 same patients were examined for ZN staining and GeneXpert tests. The samples of sputum and BAL were processed as per the standard guidelines. Results: Total of 1000 specimens (700 sputum & 300 BAL) were considered for the results. Out of 1000 specimens 300 patients had submitted both sputum as well as BAL specimens. These 300 specimens were analyzed for comparative results. Out of 300 common samples, 109 (36.3%) sputum and 136 (45%) BAL samples are positive by ZN stain. Whereas, Out of 300 common samples, 149 (49.6%) sputum and 170 (56.6%) BAL samples are positive by GeneXpert method. Out of 149 common specimens that were positive by GeneXpert, 5(3.3%) were found to be Rifampicin resistant. Conclusion:Incidence of MDR TB is 3.3% in our hospital. BAL was found to be superior specimen to sputum for the diagnosis of ZN smears negative pulmonary TB. Sensitivity and specificity of GeneXpert is higher than AFB smear microscopy.