Serologic tests for syphilis and the false-positive reactor

The role of treponemal and nontreponemal tests in the serodiagnosis of syphilis is reviewed. Diagnostic problem cases should be evaluated by treponemal tests to distinguish latent syphilis from false-positive reactions. A comparison of treponemal tests performed on serum from 101 late latent and tertiary syphilitics showed that the fluorescent treponemal antibody absorption (FTA-ABS) test is more sensitive than the Treponemapallidumimmobilization (TPI) or FTA-200 tests. Objective evidence of late syphilis was present in 6 of 11 patients with discordant test results (TPI nonreactive; FTA-ABS reactive). Of the 50 chronic false-positive reactors studied, 24 had evidence of lupus erythematosus or another of the autoimmune diseases.