Diagnostic comparison of two staining techniques in sputum samples of pulmonary tuberculosis cases

Background: Smear microscopy remains the cornerstone for the diagnosis, treatment initiation; follow up of Pulmonary Tuberculosis (PTB) in high burden countries like India. Aim of the study: The objective of this study was to compare the diagnostic efficacy of Ziehl Neelsen (ZN) and Fluorescent Auramine O (AO) staining for the detection of Mycobacterium tuberculosis before and after sputum decontamination. Material and Methods: Fifty cases (n=50) of clinically diagnosed pulmonary tuberculosis were included in the study. Sputum smears were stained by ZN and AO stain both before and after decontamination by NaLC-NaOH method. Result: Smear positivity rate was 76% by ZN staining before decontamination and it increased to 96% after decontamination. However, AO staining sensitivity was 100% both before and after decontamination. Conclusion: AO staining is highly sensitive than ZN staining in detecting even paucibacilliary cases even in direct sputum smears. Sputum decontamination improves the diagnostic efficacy of sputum smears.