Comparison of Six Automated Treponema-Specific Antibody Assays

Abstract

bSix different Treponema (TP)-specific immunoassays were compared to the fluorescent treponemal antibody absorption (FTA-ABS) test. A total of 615 samples were tested. The overall percent agreement, analytical sensitivity, and analytical specificity of each assay compared to the FTA-ABS test were as follows: Architect Syphilis TP, 99.2%, 96.8%, and 100%; Cobas Syphilis, 99.8%, 99.4%, and 100%; ADVIA Centaur Syphilis, 99.8%, 99.4%, and 100%; HISCL Anti-TP assay kit, 99.7%, 98.7%, and 100%; Immunoticles Auto3 TP, 99.0%, 97.5%, and 99.6%; Mediace TPLA, 98.0%, 98.1%, and 98.0%. All results that were discrepant between the TP-specific assays were associated with samples from noninfectious cases (11 immunoassay false positives and 7 from previous syphilis cases). Our study demonstrated that TP-specific immunoassays generally showed high sensitivities, specificities, and percentages of agreement compared to FTA-ABS, with rare cases of false-positive or false-negative results. Therefore, most TPspecific immunoassays are acceptable for use in screening for syphilis. However, it is important to perform a thorough review of a patient's clinical and treatment history for interpreting the results of syphilis serology. Syphilis is commonly diagnosed on the basis of the results of a combination of serological tests to detect Treponema (TP) antibodies and non-TP antibodies (1). A traditional screening algorithm for syphilis that began with a non-TP assay failed to detect 3% of syphilis cases, in a previous study (2). Recently, a reversescreening algorithm with an automated TP-specific assay has been recommended by the European Centers for Disease Control and Prevention (ECDC) (3). CDC continues to recommend the traditional algorithm and yet also recognizes the recent trend of the widespread use of the reverse algorithm and recommends extra TP tests to resolve discordant results (4). The reverse algorithm has been found to show superior diagnostic performance, with sensitivities ranging from 99.38% to 99.85%, specificities from 99.98% to 100%, and accuracies from 99.93% to 99.96% compared with a 24.2% missed-diagnosis rate and 75.81% sensitivity of the traditional algorithm (5).Various automated TP-specific immunoassays have been developed that use either whole cells or antigens, such as 15TpN, 17TpN, and 47TpN, derived from the Nichols strain of Treponema pallidum, to detect IgG, IgM, or total immunoglobulins (1). Initially, enzyme immunoassays (EIAs) were commonly used to detect TP-specific antibodies (5, 6). However, the use of chemiluminescence immunoassays (CLIAs) to detect TP-specific IgG and IgM antibodies has been gradually increasing (6, 7). Additionally, quantitative TP-specific immunoassays using turbidimetry, based on a latex agglutination method, have been widely used in Asia. However, comparative analyses of the performances of these various methods are lacking.The aim of this study was to evaluate the performances of 6 commonly used TP-specific immunoassays, including CLIAs and turbidimetry assays, in comparison w...

Evaluation of Elecsys Syphilis Assay for Routine and Blood Screening and Detection of Early Infection

“…For samples from blood donors and routine diagnostic requests, the findings presented in this study agree with those of a previous performance evaluation of the Elecsys Syphilis assay, in which the specificity and sensitivity were found to be 99.88% with 8,063 negative samples from target cohorts, i.e., blood donation and routine testing samples, and 99.57 to 100.00% with 928 banked syphilis-positive samples, respectively ( 22 ). The specificity and sensitivity of the comparator assays evaluated in this study are also in agreement with previously published studies ( 22 , 24 – 28 ).…”

“…The specificity and sensitivity of the comparator assays evaluated in this study are also in agreement with previously published studies (22, 24–28). …”

Comparison of Traditional and Reverse Syphilis Screening Algorithms in Medical Health Checkups

“…In contrast, the high detection sensitivity obtained by using an antibody specific for T. pallidum is advantageous in situations of low syphilis prevalence, such as in general health checkups. Moreover, the commercial T. pallidum -specific immunoassays currently in use exhibit high sensitivity and specificity [ 11 ].…”

Evaluation of the Elecsys Syphilis electrochemiluminescence immunoassay as a first-line screening test in the reverse algorithms for syphilis serodiagnosis

“…Diagnostic performance is mainly determined by the performances of the initial screening and confirmatory tests or seroprevalence. The initial screening test of the reverse and ECDC algorithms in our study, Elecsys Syphilis, showed the best diagnostic accuracy, a sensitivity of 99.4%, and specificity of 100%, when compared with the other five automated treponemal assays (Park et al, 2016). The second treponemal test in our study, TPPA, is generally recommended as a confirmatory test because of its excellent performance, sensitivity of 99.1%, and specificity of 100%, which is the best among the agglutination assays (Cole et al, 2007).…”