Comparative evaluation of commercial fluorescent treponemal antibody-absorbed test kits

We describe a comparative evaluation of commercial fluorescent treponemal antibody-absorbed test kits, using 150 selected patient sera. The ability of the test kits to detect reactive sera varied from 82.5 to 95%; that for nonreactive sera varied from 80.9 to 96.4%. Reproducibility of reactive and nonreactive results, measured by between-assay and within-assay studies, averaged 42%. The results showed substantial variation in performance characteristics among the kits, with important clinical implications for the diagnosis of syphilis. We recommend the development of an immunological standard for use in the manufacture of fluorescent treponemal antibody-absorbed test kits, with the goal of obtaining uniform performance characteristics among commercial test kits.