EVALUATION OF A TREPONEMA-PALLIDUM ENZYME-IMMUNOASSAY AS A SCREENING-TEST FOR SYPHILIS

The CAPTIA Syphilis-G enzyme immunoassay for the detection of antibodi es to Treponema pallidum was evaluated as a screening test for syphili s in comparison with the standard rapid plasma reagin (RPR) test. One thousand samples were tested, and the standard. fluorescent treponemal antibody absorption test and the standard microhemmaglutination test were used to confirm the presence of treponemal antibodies. Diagnosis of syphilis was based on traditional standard serology results. Clinic al data used in the diagnosis of patients whose samples yielded confli cting results were provided by physicians. Initially, 7 patients whose samples were reactive in the RPR test and 14 patients whose samples y ielded positive or equivocal results in the CAPTIA Syphilis-G test wer e diagnosed as not being infected. After discrepancies due to technica l problems were reconciled, samples from six patients remained reactiv e in the RPR test and that from one patient remained positive in the C APTIA Syphilis-G test. In addition, seven patients whose samples were nonreactive in the RPR test and two patients whose samples were negati ve in the CAPTIA Syphilis-G test were diagnosed as having untreated sy philis. After discrepancies were reconciled, samples from five patient s remained nonreactive in the RPR Lest and none remained negative in t he CAPTIA Syphilis-G test. Final results indicate that the sensitiviti es of the RPR test and the CAPTIA Syphilis-G test are 86.1 and 100%, r espectively, and that the specificities are 99.4 and 99.9%, respective ly. In addition to the improved sensitivity and specificity of the CAP TIA Syphilis-G screen, other potential benefits