Abstract: Objective  To evaluate the application of fluorescent microscopy for detection of acid-fast bacilli (AFB). Methods  2157 clinical samples were collected from 5 clinics for pulmonary tuberculosis (PTB), and all samples were detected by fluorescent staining (FS) microscopy and Ziehl-Neelsen (Z-N) microscopy, 1245 samples were conducted sputum culture as golden standard. The sensitivity, specificity and Youden’s index (Youden’s index=(sensitivity+specificity)-1=1-(false negative rate+false positive rate)) of FS and Z-N were evaluated. All results were compaired by Chi-square test with SPSS 17.0 statistical software, and P<0.05 was set as the criteria of statistical significance.  Results The positive rate of FS was 10.8% (234/2157), and that of Z-N was 8.8% (190/2157), the difference was statistically significant between the two methods (χ²＝25.473, P<0.001). The positive rate detected by FS was 15.9% (179/1127) in the specimens of new cases, and that of Z-N was 13.2% (149/1127), the difference was also statistically significant (χ²＝18.000, P<0.001). Among the specimens tested by smear and culture, the positive rate of FS was 13.8% (172/1245) and the positive rate of L-J culture was 15.2% (189/1245), and and there was no significant difference (χ²＝2.173, P=0.140). Among the specimens of new cases tested by smear and culture, the positive rate of FS was 16.4% (128/781) and the positive rate of L-J culture was 19.7% (154/781), which was 20.3% higher than the FS, and the difference was statistically significant (χ²＝7.861, P<0.01). The sensitivity of FS was 60.3% (114/189), the specificity was 94.5% (998/1056), the false negative rate was 39.7% (75/189) and Youden’s index was 0.548; corresponding results of Z-N were 56.6% (107/189), 97.1% (1025/1056), 43.4% (82/189) and 0.537, respectively. Conclusion Compared with Z-N, FS microscopy has higher sensitivity and similar specificity. Meanwhile, FS microscopy improves work efficiency, reduces labor intensity, which is suitable for basic laboratories with heavy workload and human resources shortage.

Key words: Mycobacterium, Fluorescent dyes, Microscopy, Study for application