Comparison of Lumin LED Fluorescent Attachment, Fluorescent Microscopy and Ziehl-Neelsen for AFB Diagnosis

Design: Cross-sectional studies in Russia (n = 502) and Macedonia (n = 205), with fluorochrome-stained sputum examined by 1) the new Lumin light emitting diode (LED) fluorescent attachment on a light microscope, and 2) conventional fluorescent microscope (CFM) available in each laboratory, and compared to 3) Ziehl-Neelsen (ZN) restaining/reading of the same smears. Poor readings of ZN-restained smears in Russia stimulated a retrospective laboratory registry analysis for sensitivity and specificity of directly ZN-stained smears (n = 791) from a previous period.

Results: In Macedonia, the sensitivity of the Lumin and CFM were 87.8%, and that of restained ZN smears with conventional light microscope was 78.0%. In Russia, sensitivity was as follows: Lumin 72.8%, CFM 52.5%; re-stained ZN smears 28.5% and directly ZN stained smears 55.6%.

Conclusion: Fluorescence microscopy is more sensitive than conventional microscopy. The Lumin attachment to conventional light microscopes provided results equal to or better than the CFMs. Smear restaining for ZN showed a 12% advantage for Lumin and CFM in Macedonia, in line with other meta-analyses. Restaining for ZN gave poor results in Russia for unknown reasons. Retrospective analysis of directly ZN-stained smears showed 55.6% sensitivity compared to the Lumin (72.8%), which is also in line with the superiority of fluorescent microscopy reported in literature.