Performance evaluation of nine different syphilis serological tests in comparison with the FTA-abs test

Serological methods have great importance for the detection of Treponema pallidum antibodies in syphilis diagnosis. The goal of the present study is to evaluate various commercially available screening assays in comparison with the FTA-abs test.

A total of 363 serum samples were enrolled in the study. Following routine testing including RPR and TPHA tests, each sample was tested by treponemal immunoassays (Chorus Syphilis Screen Recombinant, Architect Syphilis TP, Syphilis Virclia Monotest, Siemens Advia Centaur Syphilis, Euroimmun Treponema pallidum Screen ELISA, Vircell Syphilis ELISA IgG + IgM, SD Bioline Syphilis). The result obtained from each test was compared with the confirmatory FTA-abs test. Kappa (κ) coefficients were used to compare the concordance of the tests.

When the various tests were evaluated in comparison with the FTA-abs test, the sensitivity, specificity and percent agreement of each test were as follows: Architect Syphilis TP, 92.3%, 94.5%, 92.8%; Chorus Syphilis Screen Recombinant, 87.9%, 91.2%, 88.7%; Syphilis Virclia Monotest, 80.5%, 97.8%, 84.9%; Siemens Advia Centaur Syphilis, 87.5%, 89%, 87.9%; Euroimmun Treponema pallidum Screen ELISA, 87.5%, 85.7%, 87.1%; Vircell Syphilis ELISA IgG + IgM, 73.2%, 62.6%, 70.5%; TPHA, 89%, 63.7%, 82.6%; SD Bioline Syphilis, 58.1%, 94.5%, 67.2%; RPR test, 57.7%, 57.1%, 57.6%.

The results of the present study show that Treponema pallidum specific immunoassays with a performance similar or better than TPHA test generally performed well with the confirmatory FTA-abs test and may be an alternative for screening total antibodies in syphilis infection.