A Comparative Study of Treponema pallidum Antibodies Test by Electrochemiluminescence Immunoassay and Treponema pallidum Particle Agglutination Assay

Abstract

Analysis of Treponema pallidum antibodies (treponemal antibodies) in serum is a laboratory test for diagnosing syphilis and confirming infections in patients, whether current or previous. The traditional assay for treponemal antibody testing is the Treponema pallidum particle agglutination (TPPA) assay. However, this assay requires expertise, as the results must be observed by the naked eye, and has a long assay duration, making it unsuitable for laboratories with a high sample volume. Currently, the automated electrochemiluminescence immunoassay (ECLIA) using Elecsys Syphilis reagent has been developed as an alternative option for treponemal antibody detection. This study aimed to compare the consistency of the ECLIA with the TPPA assay for treponemal antibody detection using 299 samples. Precision testing of the ECLIA demonstrated good precision within acceptable criteria. The concordance of both methods was strong at 99.33% (Cohen’s kappa 0.985), indicating highly consistent results. The ECLIA could distinguish the nonreactive group from both the reactive titer 1:160 and reactive titer ≥1:320 groups (p < 0.001). However, it could not differentiate between the reactive titer 1:160 group and the reactive titer ≥1:320 group (p = 0.172). In conclusion, the ECLIA could be used for preliminary screening to separate patients into nonreactive and reactive groups. It might help reduce the number of samples requiring TPPA testing. Decreasing the assay period would increase the efficiency of patient management and treatment