Usefulness of Light Emitting Diode (LED) fluorescent microscopy as a tool for rapid and effective method for the diagnosis of pulmonary tuberculosis

Abstract

Tuberculosis remains world's leading cause of death from a single infectious agent. Fluorescence microscopy offers well-described benefits, comparing with brightfield microscopy, for the evaluation sputum smear samples for tuberculosis. We evaluated the diagnostic performance of fluorescence microscopy, using novel Light Emitting Diode (LED) technology as an alternative to the conventional fluorescence microscopy by Auramine stain as well as brightfield microscopy by Ziehl-Neelsen (ZN) stain. The objective of the study was to see the usefulness of LED fluorescent microscopy in the diagnosis of pulmonary tuberculosis. This is a prospective study consisted of 150 sputum samples from the patients of NIDCH, Mohakhali. All samples were stained by auramine and ZN stain at BSMMU and culture was done in Lowenstein-Jensen (L-J) media as gold standard at NTRL, Mohakhali. In this study total 66 (44%) out of 150 sputum specimens were positive for Mycobacterium Tuberculosis by culture. Sensitivity and specificity documented for the different modalities were 95.38% and 94.11%, respectively, for the LED assessment; 68.18% and 90.47%, respectively, for the CFM assessment; and 56.06% and 97.61%, respectively, for brightfield microscopy by ZN stain. The difference in their case detection rate was statistically significant (chi2=119.38, p<0.001). Fluorescence Microscopy (FM) is more sensitive than ZN for diagnosis of pulmonary tuberculosis. However, since FM is more sensitive and rapid, using this method (LED) in clinical laboratories with large specimen numbers is recommended.