LAUSR

BACKGROUND Considering the rapid increase of syphilis infections in several countries including China, searching for a screening test with sufficient sensitivity and specificity is extremely urgent. The current study mainly researched the performance for Treponema pallidum (TP) detection by electro-chemiluminescence immunoassays (ECLIA), chemiluminescence immunoassays (CLIA) and four commercially available ELISA assays commonly used in China. METHODS 1372 plasma samples collected from blood centers/banks were tested with 6 assays in 8 laboratories with the Western blot (WB) or TP particle agglutination assay (TPPA) as confirmatory tests. RESULTS With the WB or TPPA as confirmatory test, the ECLIA demonstrated the highest specificity (95.2%) and Kappa coefficient (0.915), but lowest sensitivity (97.2%) compared with the other 5 assays. While the Wantai-ELISA showed the highest sensitivity (99.6%) among the 6 assays. Sensitivities were found to be significantly increased when any two of the six assays were combined for TP detection. Our study demonstrated that the Wantai-ELISA combined with the ECLIA or the KHB-ELISA or the InTec-ELISA would increase the sensitivities up to 100%. Further analysis showed that the specificities and positive predictive values were both 100.0% when cut-off of S/CO values were served as 15.42 for the ECLIA and 7.14 for the CLIA, indicating that samples under these conditions can be directly considered as positive without confirmation. CONCLUSIONS The CLIA and the ECLIA are more specific than ELISA to detect TP antibodies. However, ELISA is a sensitive method, especially in combination with the CLIA or the ECLIA or another types of ELISA, suitable for the routine screening of blood donations in China.