Abstract: Objective To assess the efficacy of fluorescence microscopy with light-emitting diodes (LED) in clinical tuberculosis detection. Methods With 3881 sputum smears from TB lab in Huaiyin district, Huaian city, the positive rate of the smears by Ziehl-Neelsen(Z-N), conventional fluorescence microscopy(FM) and LED were compared respectively. Moreover, the relevance between the clinical diagnosis and Z-N or LED was analyzed through retrospective study. 
Results All 3881 smears were rechecked by provincial reference Lab (PRL). Of Z-N smears 284 were positive, with positive rate 14.6% (284/1941), 4 were low-false-positive, and 9 low-false-negative; of fluorescent smears, LED detected 498 positive and there were 464 positive after rechecking by FM, 39 were low-false-positive and 6 were low-false-negative. The positive rate of fluorescent smears was 23.9% (464/1940). With McNemar-Bowker test analysis, there were significant differences among the results of LED and the other two methods (P<0.001). The consistency of LED vs FM (Kappa=0.903) was much higher than LED vs Z-N (Kappa=0.409). For 78 new smear-positive patients, there was no difference between Z-N and LED. But LED detected 14 positive patients out of Z-N-negative. During follow-up patients, the positive of LED and Z-N was 228 and 195 respectively. Conclusion LED had a high consistency with FM and was obviously better than Z-N in detecting Mycobacterium tuberculosis and monitoring the follow-up.

Key words: Mycobacterium tuberculosis, Microscopy,fluorescence