Comparative Performance of the Reverse Algorithm Using Architect Syphilis TP Versus the Traditional Algorithm Using Rapid Plasma Reagin in Florida's Public Health Testing Population

In Florida, where syphilis is a reportable disease, the number of primary and secondary (P&S) syphilis cases has increased from 3,266 in 2008–2010 to 5,340 in 2013–2015, a 63% increase. The objective of this study was to compare the performance and sensitivity of the syphilis reverse algorithm with the traditional algorithm for detecting P&S (infectious) syphilis cases. Clinical specimens from individuals who self-referred for syphilis testing at public health clinics were processed using the traditional algorithm (non-treponemal rapid plasma reagin (RPR) test followed by a confirmatory treponemal (EIA) test) and then further tested with the Architect Syphilis TP (ASTP) immunoassay (Abbott Diagnostics, Chicago, IL, USA) or by RPR confirmation, if needed (reverse algorithm). Of 1,079 specimens, 59 were positive for syphilis. The sensitivity of the reverse algorithm was 98.3% (58/59) and of the traditional algorithm was 72.9% (43/59). Based on clinical evidence, of the 16 traditional algorithm-negative but reverse algorithm-positive cases, 68.8% (11/16) were classified as missed P&S infections (treatment naïve) and 31.2% (5/16) were classified as missed past syphilis (latent or infections with documented linkage to care). The reverse algorithm enables the detection of additional P&S syphilis cases missed by our current traditional algorithm.

Evaluation of Automated Architect Syphilis TP as a Diagnostic Laboratory Screening Test for Syphilis / 대한진단검사의학회지

BACKGROUND: The aim of the study was to establish a new syphilis test algorithm using Architect Syphilis TP (Abbott Japan, Japan: AST), a fully automated treponemal antibody test, as a screening test in a university hospital laboratory. We evaluated performance characteristics of AST in various patient groups. METHODS: A total of 1,357 serum samples obtained from patients at a university hospital from June to August, 2008 were categorized into checkup, preoperative, other diseases, diagnosis (clinically suspected of syphilis), and follow up groups. We compared the results of AST with those of RPR (N=1,276) or Treponema pallidum hemagglutination assay (TPHA, N=81). Samples with discrepant results between RPR or TPHA and AST were retested by fluorescent treponemal antibody absorption test (FTA-ABS) and all patients' clinical records were thoroughly reviewed. RESULTS: The positive rate of AST was significantly higher than that of RPR in preoperative and other diseases groups and was the same as that of RPR in diagnosis group. There were no significant differences in check up and follow up groups. The results of AST showed 97.4% (1,243/1,276) and 97.5% (79/81) concordance rates with those of RPR and TPHA, respectively. Among 26 RPR-AST discrepant and FTA-ABS confirmed cases, there were 20 RPR false-negatives, 4 RPR false-positives, 1 AST false-negative, and 1 AST false-positive. CONCLUSIONS: Based on the results and literature review, we established a new syphilis test algorithm using AST as a screening test, which would be helpful for detection of more syphilis patients including latent infections.