Comparative Sensitivity of ARCHITECT Syphilis TP with Other Antibody Tests

Kim, Young Hyu; Kim, Hyung Rag; Park, Chul; Seo, Min Young; Park, Joonseok

Abstract

BACKGROUND: Serological tests detecting antibodies specific to antigens of Treponema pallidum are useful tools for diagnosis and screening of syphilis. Nevertheless, conventional non-treponemal tests, which are commonly being used thanks to their low cost, have limited consistency in procedures and interpretations because of lack of automation. Moreover, they have innate lower sensitivity and specificity. Therefore, clinical use of non-treponemal tests has been significantly substituted by more reliable treponemal antibody assays. Considering such trend, diagnostic sensitivity of a recently introduced automatic chemiluminescent immunoassay, ARCHITECT Syphilis TP (Abbott Japan, Tokyo, Japan), was evaluated with comparison to existing methods to validate its clinical sensitivity.
METHODS
Fifty stored sera with reactive results on a non-treponemal syphilis test done by requests from the attending physicians were collected consecutively. Diagnosis of syphilis was confirmed when two or more positive results were obtained among 3 treponemal antibody tests, a hemagglutination, an automated latex turbidimetry and ARCHITECT Syphilis TP.
RESULTS
All 50 sera were confirmed as syphilis-infected. Diagnostic sensitivity of ARCHITECT Syphilis TP was estimated to 100%, whilst that of the hemagglutination and the latex turbidimetry was 94% and 98%, respectively. Correlation coefficient between S/COs of ARCHITECT Syphilis TP and quantitative results on the latex turbidimetry was caculated as 0.865. Compared to the hemagglutination titers, better quantitative correlation was observed with S/COs of ARCHITECT Syphilis TP.
CONCLUSIONS
ARCHITECT Syphilis was thought to be a reliable test with good sensitivity and its automated feature was thought to be additionally beneficial. Although it is being used for a qualitative purpose, it seemed possible to expand its utility into quantitative use considering its acceptable quantitative correlation with the hemagglutination assay as well as the automated latex turbidimetric assay.