Comparative Evaluation of Nine Different Enzyme-Linked Immunosorbent Assays for Determination of Antibodies against Treponema pallidum in Patients with Primary Syphilis

Nine different enzyme-linked immunosorbent assays (ELISAs) with a sonicate or recombinant proteins of Treponema pallidum as antigen have been evaluated comparatively by testing 52 highly selected sera from patients with primary syphilis, all negative in the microhemagglutination test for T. pallidum (MHA-TP). Eight tests exhibited greater sensitivity (48.5 to 76.9%) than the commonly used Venereal Disease Research Laboratory test (44.2%). Higher sensitivity could be related to (i) the volume and dilution of the serum, (ii) the design of the assay (capture and competitive tests showed higher sensitivity than sandwich-based assays), and (iii) the ability to detected specific immunoglobulin M antibodies. The specificity of the ICE Syphilis and the Enzygnost Syphilis tests was 99.5 and 99.8%, respectively, as determined by routine testing of 2, 053 unselected sera in comparison with the MHA-TP test. ELISAs tested offered high sensitivity in patients with primary syphilis; however, recommendations to use these tests as screening assays do need further data on specificity and reactivity in late stages of the disease.