Evaluation of different confirmatory algorithms using seven treponemal tests on Architect Syphilis TP-positive/RPR-negative sera

Jonckheere, Stijn; Berth, Mario; Esbroeck, Marjan Van; Blomme, S; Lagrou, Katrien; Padalko, Elizaveta

doi:10.1007/s10096-015-2449-z

Cited by 8 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Jonckheere et al . [ 16 ] tested 178 RPR negative samples using Architect at S/CO values ranged between 1 and 15. Based on TP-PA confirmatory assay, specimens with S/CO > 5.6 were considered positive and do not require further confirmation testing as compared to the higher S/CO threshold of 16.4 predicted in our study.…”

Section: Discussionmentioning

confidence: 99%

Improvement of reverse sequence algorithm for syphilis diagnosis using optimal treponemal screening assay signal-to-cutoff ratio

et al. 2018

View full text Add to dashboard Cite

BackgroundAlthough reverse sequence algorithms (RSA) for syphilis screening are performing well, they still have to rely on treponemal confirmatory tests at least for sera reactive by enzyme immunoassay/chemiluminescence immunoassay (EIA/CIA) and unreactive by rapid plasma reagin (RPR). Quebec’s laboratory network previously showed that 3.3% of EIA/CIA reactive and weakly-reactive RPR samples (RPR titer of 1 to 4) would have been misclassified as syphilis cases if a treponemal confirmatory test had not been performed.ObjectivesTo correlate the magnitude of signal-to-cutoff (S/CO) ratios of the 4 most used commercial first-line EIA/CIA kits in Quebec with syphilis confirmation results and establish a S/CO value above which treponemal confirmation would not be required.MethodsSerum samples from previously undiagnosed individuals (n = 7 404) obtained between January 2014 and February 2017 that were reactive by EIA/CIA and either negative by RPR or reactive with a low titer (1 to 4) were included in the study. All samples were tested with Treponema pallidum particle agglutination (TP-PA) and, if negative or inconclusive, with a line immunoassay (LIA). Syphilis infection confirmation was defined by a reactive TP-PA or LIA. Logistic regression analysis was used to determine S/CO values (95% CI lower bound = 0.98) above which confirmation would not be required. The four kits studied were Architect TP, BioPlex IgG, Syphilis EIA II, and Trep-Sure.ResultsOf 2609 reactive EIA/CIA specimens tested for the determination of S/CO values, 1730 (66%) were confirmed as true syphilis cases. Confirmation rate was significantly higher in samples with low-titer positive RPR (92%) than with negative RPR samples (54%); p<0.01. A linear probability model (95% CI lower bound = 0.98) predicted the S/CO value above which a confirmation would no longer be needed for the Architect TP (16.4), Bioplex IgG (7.4) and Trep-Sure (24.6). No linearity was observed between the S/CO value of Syphilis EIA II and the confirmation rate. The validity of the predicted S/CO values was investigated using 4 795 specimens. The use of an S/CO value of 16.4 with the Architect TP kit and of 24.6 for the Trep-Sure kit would obviate the need for confirmation of 18.5% and 13.2% of sera from the all RPR subgroup, respectively. For the BioPlex IgG kit, 81.1% of sera would not require confirmation when using the S/CO value of 7.4 in the low titer RPR subgroup.ConclusionSignal-to-cut-off values could be used to identify sera that do not require extra treponemal confirmation for 3 of the 4 most used first-line EIA/CIA kits in Quebec. Using these values in our current reverse screening algorithm (RSA) would avoid the need for confirmatory tests in 14 to 20% of sera, a proportion that could reach 75% among low-titer RPR.

show abstract

Section: Discussionmentioning

confidence: 99%

Improvement of reverse sequence algorithm for syphilis diagnosis using optimal treponemal screening assay signal-to-cutoff ratio

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Our retrospective data add to the body of evidence that the screening titer for RPR and quantitative antibody index values for syphilis IgG correlate with the probability of confirmation [4] , [7] , [8] , [23] , [24] . The higher the RPR titer and syphilis IgG value, the more likely a patient is to confirm with subsequent testing.…”

Section: Discussionmentioning

confidence: 62%

Traditional versus reverse syphilis algorithms: A comparison at a large academic medical center

Dunseth

Ford

Krasowski

2017

Practical Laboratory Medicine

View full text Add to dashboard Cite

ObjectivesAn increasing number of institutions are transitioning from the traditional syphilis testing algorithm (initial screening with nontreponemal tests) to the ‘reverse’ algorithm (initial screening with treponemal tests such as syphilis IgG). The aim of this study was to evaluate the switch in syphilis algorithm at an academic medical center with a population with low syphilis prevalence.Design and methodsWe performed a six-year retrospective study at the University of Iowa Hospitals and Clinics, an academic medical center, comparing the traditional algorithm (n=12,612) with the reverse algorithm (n=10,453). False positives were considered to be positive screens with negative confirmatory testing.ResultsUsing the traditional algorithm, 93 samples (0.7% of total) screened positive with RPR, with 40 of these samples having negative TP-PA testing (43% of positive screens, 0.3% of total). Using the reverse algorithm, 110 screened positive with syphilis IgG (1.1% of total), and 33 of these samples had both negative RPR and TP-PA (30% of positive screens, 0.3% of total). In both algorithms, higher RPR titers and syphilis IgG values were associated with increased probability of positive confirmation.ConclusionsIn this study at an academic medical center, the reverse algorithm had significantly more total positive screens than the traditional algorithm. Both algorithms produced equivalent rates of active infection. The quantitative difference in positives between the two algorithms are the category of patients who are syphilis IgG positive, RPR non-reactive, and TP-PA reactive. Specimens with higher RPR titers and syphilis IgG values are more likely to confirm positive.

show abstract

“…This test has shown perfect performance when compared to the TPPA 15 and could be used as a reliable test for the detection of syphilis. 16,17 The results of the chemiluminescent reaction are measured in relative light units (RLUs), with an RLU value of <1.00 indicating a negative result and an RLU value of 1.00 indicating a positive result. The level of RLUs is directly related to the amount of anti-T. pallidum antibodies in the serum.…”

Section: Architect Syphilis Tpmentioning

confidence: 99%

A novel ELISA using a recombinant outer membrane protein, rTp0663, as the antigen for serological diagnosis of syphilis

Xie

Jiang

et al. 2016

International Journal of Infectious Diseases

View full text Add to dashboard Cite

show abstract

Evaluation of different confirmatory algorithms using seven treponemal tests on Architect Syphilis TP-positive/RPR-negative sera

Cited by 8 publications

References 15 publications

Improvement of reverse sequence algorithm for syphilis diagnosis using optimal treponemal screening assay signal-to-cutoff ratio

Improvement of reverse sequence algorithm for syphilis diagnosis using optimal treponemal screening assay signal-to-cutoff ratio

Traditional versus reverse syphilis algorithms: A comparison at a large academic medical center

A novel ELISA using a recombinant outer membrane protein, rTp0663, as the antigen for serological diagnosis of syphilis

Contact Info

Product

Resources

About