Evaluation of new algorithm using TPLA as an initial syphilis screening test.

We retrospectively compared the performance of an existing syphilis diagnostic algorithm with a new algorithm that analyzes the results of Treponema pallidum latex agglutination (TPLA) tests. Of the 100 clinical blood samples, 51 were classified as positive through both Mediace TPLA and ESPLINE TP; 2/51 were classified as negative by Architect Syphilis TP, whereas 1/51 was negative as per LUMIPULSE Presto TP. The false positive rate when the results of Mediace TPLA and ESPLINE TP were combined was 1.96% versus 0% for both Architect Syphilis TP and LUMIPULSE Presto TP. The sensitivity of Mediace TPLA (98%) was comparable to that of Architect Syphilis TP (98%) but lower than that of LUMIPULSE Presto TP (100%). The specificity of Mediace TPLA was 98.0% versus 100% for Architect Syphilis TP, and versus 100% for LUMIPULSE Presto TP. We conclude that the performance of Mediace TPLA in combination with a reverse algorithm is nearly equal to that of enzyme immunoassay (EIA) or chemiluminescence immunoassay (CIA). Because TPLA is low cost, highly sensitive method for IgM detection, and is easy to operate, we have recommended its adoption for initial syphilis screening tests.