Clinical Comparison of the Treponema pallidum CAPTIA Syphilis-G Enzyme Immunoassay with the Fluorescent Treponemal Antibody Absorption Immunoglobulin G Assay for Syphilis Testing

Abstract

Recently, a treponema-specific immunoglobulin G (IgG) enzyme immunoassay (EIA), the CAPTIA Syphilis-G (Trinity Biotech, Jamestown, N.Y.), has become available as a diagnostic test for syphilis. A total of 89 stored sera previously tested by the fluorescent treponemal antibody absorption (FTA-ABS) IgG assay were evaluated by the CAPTIA EIA. The FTA-ABS IgG procedure was performed by technologists unblinded to results of rapid plasmid reagin (RPR) testing of the same specimens. Borderline CAPTIA-positive samples (antibody indices of ≥0.650 and ≤0.900) were retested; if the second analysis produced an index of >0.900, the sample was considered positive. Thirteen of 89 (15%) samples had discrepant results. Compared to the FTA-ABS assay, the CAPTIA EIA had a sensitivity and specificity and positive and negative predictive values of 70.7, 97.9, 96.7, and 79.7%, respectively. In another analysis, discrepancies between results were resolved by repeated FTA-ABS testing (technologists were blinded to previous RPR results) and patient chart reviews. Seven CAPTIA-negative samples which were previously interpreted (unblinded) as minimally reactive by the FTA method were subsequently interpreted (blinded) as nonreactive. One other discrepant sample (CAPTIA negative and FTA-ABS positive [at an intensity of 3+], unblinded) was FTA negative with repeated testing (blinded). For the five remaining discrepant samples, chart reviews indicated that one patient (CAPTIA negative and FTA-ABS positive [minimally reactive], blinded) had possible syphilis. These five samples were also evaluated and found to be negative by another treponema-specific test, the Treponema pallidum microhemagglutination assay. Therefore, after repeated testing and chart reviews, 2 of the 89 (2%) samples had discrepant results; the adjusted sensitivity, specificity, and positive and negative predictive values were 96.7, 98.3, 96.7, and 98.3%, respectively. This study demonstrates that the CAPTIA IgG EIA is a reliable method for syphilis testing and that personnel performing tests which require subjective interpretation, like the FTA-ABS test, may be biased by RPR test results.

Performance Evaluation of CLIA for Treponema Pallidum Specific Antibodies Detection in Comparison with ELISA

“…Figure d indicated that with TPPA as the confirmatory test both CLIA and ELISA had good diagnosis efficiency (all the AUCs ≥ 0.95), and CLIA was better. Compared with other studies , the sensitivity and specificity of CLIA and ELISA in our study were close or similar to others’—which indicated that the difference of reference/confirmatory tests may not be the critical factor to influence the sensitivity and specificity of evaluated assays. Wellinghausen N et al and we both appraised diagnostic efficiency of CLIA with different confirmatory tests (FTA‐ABS in Wellinghausen N et al's study and TPPA in our study).…”

Patterns of prevalent HPV and STI co-infections and associated factors among HIV-negative young Western Cape, South African women: the EVRI trial

“…All specimens positive for syphilis were confirmed positive by a repeat test with the same assay. 21 The Captia™ Syphilis ( Treponema pallidum )-G test may test positive in patients with active or inactive disease and those with previously treated infection. 21 HSV-2 antibody status was measured by the Captia HSV-2 type specific IgG enzyme-linked immunoassay (EIA, Trinity Biotech).…”

Current and Best Practices for Testing of Sexually Transmitted Diseases

“…Recently, an immunoglobulin G (IgG) EIA has become available as a diagnostic test for syphilis. 12 This test, which detects treponema-specific antibodies, has the potential to be automated and produces an objective result without requiring confirmation (unlike the reactive plasma reagin [RPR] or other non-treponemal tests). Clinicians now have a choice of several type-specific HSV antibody tests based on the glycoprotein G antigens of HSV-1 and HSV-2.…”

“…Associate Professor of Medicine, Division of Infectious Diseases at the University of North Carolina at Chapel Hill, NC and is Medical Director of the Durham County Health Department, Durham, NC. She can be reached at idrod@med.unc.edu.Telephone: 919-966-2536 2,4,7,[10][11][12][13]. women, but these molecular tests are available only in clinical research settings 5.…”