Inmunoensayo quimioluminiscente para sífilis en donantes de sangre: ¿Los valores de lectura se correlacionan con el estado de la infección? / Chemiluminescent immunoassay for syphilis in blood donors: do signal strength values correlate with the infection status? / Imunoensaio quimioluminescente para sífilis em doadores de sangue: os valores de leitura estão correlacionados com o estado da infecção?

Resumen El objetivo del trabajo fue comparar el desempeño del tamizaje treponémico y no treponémico en dos períodos próximos en el tiempo en donantes de sangre y analizar la asociación de la intensidad de la señal de la prueba quimioluminiscente (QL) con la reactividad del enzimoinmunoanálisis (ELISA) y la reagina plasmática rápida (RPR). Se realizó el tamizaje con pruebas treponémicas. Se analizó la distribución de los valores de señal/valor de corte (S/CO) obtenidos por QL en función del ELISA y RPR y se evaluó su asociación entre dos grupos de resultados de laboratorio (1) ELISA+/RPR+ y (2): ELISA+/RPR-. Se procesaron 76 794 donaciones voluntarias. Al comparar las medianas entre grupos, se encontró que la relación S/CO de QL fue significativamente mayor para los donantes del Grupo 1 (19,5 vs. 8,10; p<0,001). Se concluye que la intensidad de la señal de la prueba cualitativa QL estaría asociada con la reactividad de la RPR y guardaría relación con el curso de la infección.

Abstract The objective of this work was to compare the performance of treponemal and non-treponemal screening in two periods close in time in blood donors and to analyse the association of the signal strength (signal-to-cutoff, S/ CO) of the chemiluminescent immunoassay (CIA) with the reactivity of the enzymeimmunoassay (EIA) and the rapid plasma reagin (RPR). Donors were screened with treponemal tests. The distribution of the S/CO values obtained by CIA was analysed based on EIA and RPR, and its association was evaluated. Group 1: ELISA+/RPR+ donors and Group 2: ELISA+/RPR-. A total of 76,794 voluntary donations were processed. Comparing the means between groups, it was found that the CIA S/CO ratio was significantly higher for Group 1 donors (19.5 vs. 8.10; p<0.001). In conclusion, the signal strength of the qualitative CIA test would be associated with the reactivity of the RPR and would be related to the course of the infection.

Resumo O objetivo do trabalho foi comparar o desempenho da triagem treponêmica e não treponêmica em dois períodos próximos no tempo em doadores de sangue e analisar a associação da intensidade do sinal da prova quimioluminescente (QL) com a reatividade da análise imunoenzimática (ELISA) e a reagina plasmática rápida (RPR). Foi realizada uma triagem com provas treponêmicas. Foi analisada a distribuição dos valores de sinal/valor de corte (S/CO) obtidos por QL em função da ELISA e RPR, e também a associação entre dois grupos de resultados laboratoriais (1): ELISA+/RPR+ e (2) ELISA+/ RPR-). Foram procesadas 76 794 doações de sangue voluntárias. Ao comparar as medianas entre os grupos, obteve-se que a relação S/CO de QL foi significativamente maior para os doadores de sangue do grupo 1 (19,5 vs. 8,10; p<0,001). Em conclusão, a intensidade do sinal da prova qualitativa QL estaria associada com a reatividade da RPR e guardaria relação com o curso da infecção.

British Columbia's Experience after Implementation of the Treponema pallidum Reverse Algorithm and PCR Detection, 2015 to 2020.

British Columbia (BC) implemented the syphilis reverse screening algorithm and Treponema pallidum PCR testing in 2014. We summarize the performance characteristics of the algorithm, together with PCR direct detection, and report on syphilis cases identified from 2015 to 2020. Prior to 2015, samples for syphilis diagnosis were first screened by rapid plasma reagin (RPR). As of 2015, sera were screened by the Siemens Advia Centaur syphilis assay (enzyme immunoassay [EIA]). Positive and equivocal samples were reflex tested by a T. pallidum passive particle agglutination assay (TPPA) and RPR. We used T. pallidum DNA PCR on clinical samples and restriction fragment length polymorphism analysis to identify azithromycin resistance mutations. Case/epidemiological data were obtained from the BC surveillance system. Of 1,631,519 samples screened by the EIA, 72,492 (4.4%) were positive and 187 (<0.1%) were equivocal. Of EIA-positive/equivocal samples, 10.6% were false positive, and false positivity was higher at lower EIA indices. The reverse algorithm detected 4,693 late latent syphilis cases that likely would have been missed by RPR screening. PCR had a very high sensitivity of 100% versus 52.9% and 52.4% for dark-field (DF) and immunofluorescence (IF) microscopy, respectively. The azithromycin resistance mutation A2058G was identified in 96% of PCR-positive samples, and A2059G was identified in 4%. Annually, there were 944 to 1,467 syphilis cases, with 62% in men who reported male sexual partners. The reverse algorithm had a low false-positive rate and very few equivocal screening results but did identify previously undiagnosed late latent syphilis cases. PCR was more sensitive than both DF and IF microscopy for direct diagnosis and enabled monitoring for azithromycin resistance. IMPORTANCE In this study, we summarize the performance characteristics of the algorithm, together with PCR direct detection and epidemiological analysis, and report on syphilis cases identified from 2015 to 2020. This allowed us to paint a complete picture of the outcome of the utilization of the reverse algorithm for diagnosing syphilis cases. The study clearly showed that the reverse algorithm had a low false-positive rate and very few equivocal screening results but did identify previously undiagnosed late latent syphilis cases. PCR was more sensitive than both DF and IF microscopy for direct diagnosis and enabled monitoring for azithromycin resistance.

Reverse algorithm for screening of syphilis and trends in prevalence among blood donors in Coastal Karnataka.

BACKGROUND: Transfusion transmissible syphilis is caused by Treponema pallidum; blood donors are traditionally screened with non-treponemal antibody tests to ensure transfusion safety. Detection of specific antibodies against T. pallidum is employed in reverse algorithm screening. We aim to analyze the utility of the reverse algorithm screening strategy for T. pallidum and to determine the prevalence trends among blood donors in our centre. MATERIAL AND METHODS: The study was conducted in a Transfusion Centre catering to the 2030 bedded Tertiary Care Centre in coastal Karnataka in two timelines from 2012 to 2014, and 2019 to 2020, respectively. A fully automated Enzyme-Linked Immunosorbent Assay and Enhanced Chemiluminescence Immunoassay, which detect both IgM and IgG antibodies against T.pallidum were used in the study. Blood donor data from 2008 to 2020 were also analyzed to observe the trend in prevalence rate of syphilis among blood donors. RESULTS: Among 26329 and 388 blood donors screened with ELISA and ECI, 134 (0.51%) and 9 (2.3%) were reactive to T. pallidum antibodies respectively. TPHA confirmed that 104 and 9 donors were reactive from each of the ELISA and ECI reactive donor groups. The increase in the prevalence of syphilis was observed with the use of reverse algorithm compared to the traditional strategy. The prevalence of syphilis in the present study ranged from 0.02 to 0.28%. CONCLUSION: The reverse algorithm screening can give a better result with a positive predictive value of 77.61% and 88.9% for ELISA and ECI. respectively Our study found that the use of reverse algorithm might increase the blood discard rate slightly but adds on to safety of blood components.

Evaluation of the Diagnostic Algorithms for Serodiagnosis of Syphilis.

We analyzed the performance parameters of the traditional and reverse algorithms to determine which is more convenient for serodiagnosis of syphilis. In total, 4,789 serum samples were obtained from a cross-sectional study. Venereal Disease Research Laboratory (VDRL), Treponema pallidum hemagglutination assay (TPHA), and chemiluminescent microparticle immunoassay (CMIA) tests were performed on each serum sample. In case of discordance between results, TPHA was applied as a second treponemal test. Overall, 207 patients were serodiagnosed with syphilis. Among the 4,789 samples tested, 125 (2.6%) and 206 (4.3%) were positive using the traditional and reverse algorithms, respectively. The missed diagnosis rate of the traditional algorithm was 42.5%. The reverse algorithm had a higher sensitivity than that of the traditional algorithm. The sensitivity levels of the traditional and reverse algorithms were 57.49% and 99.85% respectively. The false positivity rate of the reverse algorithm was 0.02%.

Relationship between DiaSorin Liaison Treponema pallidum antibody indices and confirmatory assay results in the reverse syphilis testing algorithm.

Published studies show that >99% of sera reactive in the reverse syphilis testing algorithm (RSTA) screening assay with an index above an assay-specific threshold confirm as reactive, with either a rapid plasma reagin-reactive (RPRR) or RPR-nonreactive/Treponema pallidum particle agglutination-reactive (TPPAR) result. However, the relationship between screen indices and confirmatory patterns has not been characterized. We thus assessed confirmatory testing results for 577 sera submitted for RSTA testing and a screen-reactive result in the DiaSorin Liaison assay. The median screen index was significantly higher for RPRR samples than TPPAR samples (55.6 versus 10.4), and the proportion with indices >28.3 (median for all 577 samples) was significantly higher for RPRR versus TPPAR samples (82% versus 26%). However, RPRR titers did not significantly correlate with screen indices (R2 = 0.02). These findings demonstrate a significant relationship between RSTA screen indices and confirmatory assay results. The clinical utility of this relationship requires further study.

A clinical audit of maternal syphilis in a regional hospital in KwaZulu-Natal, South Africa.

BACKGROUND: Despite the availability of screening guidelines and effective treatment for maternal syphilis (MS), its prevalence remains high and is re-emerging in many parts of the world. This might be because of varying screening tests and algorithms for the laboratory diagnosis and treatment of syphilis. In addition, HIV co-infection may compromise the elimination of MS. The present study is a clinical audit of the prevalence of MS in KwaZulu-Natal, South Africa, using the 'Traditional Algorithm' screening. METHODS: This was a retrospective audit in which data on syphilis testing were obtained over a 1-year period (2016) at a large regional hospital in South Africa. The standard screening test at the study site was the non-treponemal antigen, rapid plasma reagin (RPR). Data on the prevalence of MS and comorbidity with HIV infection were analysed. RESULTS: There were 10 680 deliveries in the study period of which 118 were RPR reactive, giving an MS prevalence of 1.1%. MS occurred predominantly in the age groups < 18 and > 35 years (p = 0.001). The prevalence of HIV infection was 41.2% (n = 4451). Seventy-two (61.0%) had both HIV and MS infection, whilst 46 (39.0%) had discordant results (p = 0.001). CONCLUSION: We report an increase in the prevalence of MS compared to previous South African National Antenatal Syphilis Surveillance studies. This may be because of the prozone effect caused by HIV infection on the sensitivity of the RPR. We propose a change in MS screening, using a Rapid DUO (Dual HIV and syphilis point of care test) and Reverse Algorithm for screening that could improve the sensitivity, detection and management of both diseases.

Implementación del algoritmo reverso para el cribado de sífilis en un laboratorio clínico / Implementation of the reverse screening syphilis algorithm in a clinical laboratory

Resumen Introducción: La sífilis sigue siendo un problema de salud pública en todo el mundo; la precisión de las pruebas de diagnóstico es fundamental para el éxito de su control. Actualmente, hay dos enfoques para el diagnóstico serológico de la sífilis: el algoritmo tradicional y el algoritmo reverso. Objetivo: Analizar las ventajas y desventajas en la implementación del cribado para sífilis con el algoritmo reverso en un laboratorio clínico de pacientes ambulatorios. Materiales y Métodos: Se realizó un estudio de corte transversal analizando 246 sueros reactivos en el cribado sobre un total de 14.700 solicitudes de serología para sífilis. Se utilizaron los ensayos ARCHITECT SyphilisTP, V.D.R.L. y FTA-Abs. Resultados: De los 246 sueros reactivos por ARCHITECT Syphilis TP, 129 fueron reactivos y 117 no reactivos con V.D.R.L., éstos últimos resultaron 97 reactivos y 20 no reactivos por FTA-Abs, sugiriendo falsos positivos (0,13%). Se detectaron dos casos de infección primaria, no detectados con V.D.R.L y un caso de infección primaria en una gestante con un valor alto S/CO y V.D.R.L. de 1 dils. Conclusiones: Entre las ventajas de utilizar el algoritmo reverso se encontró mayor sensibilidad en la detección de sífilis primaria; automatización, trazabilidad, interpretación objetiva y resultados concluyentes.

Background: Syphilis remains a public health concern worldwide, the accuracy of diagnostic tests is critical for its successful control. Currently, there are two approaches to the diagnosis of syphilis using serological tests: the traditional algorithm and the reverse algorithm. Aim: The goal of this study was to analyse the advantages and disadvantages in the implementation of the syphilis reverse-screening algorithm in an outpatient clinical laboratory. Methods: An observational cross-sectional study was carried out analyzing 246 reactive sera from a total of 14700 requests for syphilis serology. Chemiluminescent assay ARCHITECT Syphilis TP, V.D.R.L. and FTA-Abs were performed. Results: Among 246 reactive sera by ARCHITECT Syphilis TP, 129 were reactive and 117 were non-reactive by V.D.R.L. the last mentioned resulted in 97 reactive and 20 non-reactive by FTA-Abs, suggesting false positives (0.13%). Two patients with primary infection were detected, that were not detected by V.D.R.L. and one pregnant woman with primary infection with a high value S/CO and V.D.R.L.:1 dils. Conclusions: Among the advantages of using a reverse algorithm were greater sensitivity in the detection of patients with primary syphilis; automation, complete traceability of the samples; objective interpretation and conclusive results.

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.

Sífilis en el siglo XXI: novedades en el enfrentamiento diagnóstico y terapéutico / Syphilis in the XXI century: novelties in the diagnostic and therapeutic confrontation

La sífilis es una enfermedad de transmisión sexual altamente contagiosa con importantes complicaciones, pero con tratamiento efectivo en etapas tempranas. Actualmente, representa un problema de salud pública. La prevalencia reportada en EEUU desde el año 2008 es de 4,5 casos/100.000 habitantes, con una incidencia 10.6 millones de casos cada año, especialmente en hombres que mantienen relaciones sexuales con hombres (HSH) y pacientes portadores de VIH (PVIH). Los métodos diagnósticos basados en test moleculares aún no han sido validados para el diagnóstico de sífilis, lo que ha permitido establecer tres esquemas serológicos con diferentes rendimientos, según prevalencia poblacional. Desde este punto de vista, el screening reverso pareciera ser útil en población de alto riesgo, y el screening tradicional para la población general.

Syphilis is a sexual transmitted disease highly contagious with important complications that can be prevented with an adequate treatment in early stages. Syphilis has become a public health issue, in the USA its incidence has increased from the 2001, with a rate in the 2008 of 4,5 cases/100000 people, with a greater prevalence in men who have sex with men (HSH) and people infected by HIV (PVIH). Despite molecular detection test are used for the diagnostic of many diseases, in syphilis we still using serologist test. There are three different schemes with different per-formance depending in the prevalence of syphilis in the population. In this setting reverse screening is the most adequate method for high prevalence versus traditional method that is better in general population.

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.

Research progress of laboratory detective algorithms for syphilis / 中华检验医学杂志

Syphilis can not be cultured in vitro.So far, serologic testing is still regarded as the mainstay for diagnosing syphilis and for monitoring the efficacy of subsequent antibiotic treatment.However, single serological tests have limitations in sensitivity or specificity.Detective algorithms with two or more serological methods will help to improve the effectiveness of syphilis diagnosis, and decrease missed diagnosis and misdiagnosis.This article will review advances on etiological examination, serological tests, and detective algorithms for syphilis.In particular, it specially introduces the merits and demerits of three detective algorithms for syphilis,so as to explore suitable screening methods,and provide basis for relevant administrative departments to formulate related laws, regulations and guidelines for syphilis.

Performance Characteristics of the Reverse Syphilis Screening Algorithm in a Population With a Moderately High Prevalence of Syphilis.

OBJECTIVES: With the recent introduction of automated treponemal tests, a new reverse syphilis algorithm has been proposed and now used by many clinical laboratories. We analyzed the impact of instituting the reverse screening syphilis algorithm in a laboratory that serves a geographic area with a moderately high prevalence of syphilis infection. METHODS: Serum samples sent for syphilis testing were tested using a treponemal enzyme immunoassay (EIA) as the screening assay. EIA reactive samples were tested by rapid plasma reagin (RPR) and titered to end point if reactive. RPR nonreactive samples were analyzed by the Treponema pallidum particle agglutination test (TP-PA). Pertinent medical records were reviewed for false-reactive screens and samples with evidence of past syphilis infection. RESULTS: Among 10,060 patients tested, 502 (5%) were reactive on the initial EIA screen. The RPR was reactive in 150 (1.5%). TP-PA testing determined that 103 (1.0%) were falsely reactive on initial EIA screen. The reverse screening algorithm, however, identified 242 (2.4%) with evidence of latent, secondary, or past syphilis, 21 of whom had no or unknown prior treatment with antibiotics. CONCLUSIONS: Despite a 1.0% false-reactive rate, the reverse syphilis algorithm detected 21 patients with possible latent syphilis that may have gone undetected by traditional syphilis screening.

Comparison of automated treponemal and nontreponemal test algorithms as first-line syphilis screening assays.

BACKGROUND: Automated Mediace Treponema pallidum latex agglutination (TPLA) and Mediace rapid plasma reagin (RPR) assays are used by many laboratories for syphilis diagnosis. This study compared the results of the traditional syphilis screening algorithm and a reverse algorithm using automated Mediace RPR or Mediace TPLA as first-line screening assays in subjects undergoing a health checkup. METHODS: Samples from 24,681 persons were included in this study. We routinely performed Mediace RPR and Mediace TPLA simultaneously. Results were analyzed according to both the traditional algorithm and reverse algorithm. Samples with discordant results on the reverse algorithm (e.g., positive Mediace TPLA, negative Mediace RPR) were tested with Treponema pallidum particle agglutination (TPPA). RESULTS: Among the 24,681 samples, 30 (0.1%) were found positive by traditional screening, and 190 (0.8%) by reverse screening. The identified syphilis rate and overall false-positive rate according to the traditional algorithm were lower than those according to the reverse algorithm (0.07% and 0.05% vs. 0.64% and 0.13%, respectively). A total of 173 discordant samples were tested with TPPA by using the reverse algorithm, of which 140 (80.9%) were TPPA positive. CONCLUSIONS: Despite the increased false-positive results in populations with a low prevalence of syphilis, the reverse algorithm detected 140 samples with treponemal antibody that went undetected by the traditional algorithm. The reverse algorithm using Mediace TPLA as a screening test is more sensitive for the detection of syphilis.

Comparison of Automated Treponemal and Nontreponemal Test Algorithms as First-Line Syphilis Screening Assays

BACKGROUND: Automated Mediace Treponema pallidum latex agglutination (TPLA) and Mediace rapid plasma reagin (RPR) assays are used by many laboratories for syphilis diagnosis. This study compared the results of the traditional syphilis screening algorithm and a reverse algorithm using automated Mediace RPR or Mediace TPLA as first-line screening assays in subjects undergoing a health checkup. METHODS: Samples from 24,681 persons were included in this study. We routinely performed Mediace RPR and Mediace TPLA simultaneously. Results were analyzed according to both the traditional algorithm and reverse algorithm. Samples with discordant results on the reverse algorithm (e.g., positive Mediace TPLA, negative Mediace RPR) were tested with Treponema pallidum particle agglutination (TPPA). RESULTS: Among the 24,681 samples, 30 (0.1%) were found positive by traditional screening, and 190 (0.8%) by reverse screening. The identified syphilis rate and overall false-positive rate according to the traditional algorithm were lower than those according to the reverse algorithm (0.07% and 0.05% vs. 0.64% and 0.13%, respectively). A total of 173 discordant samples were tested with TPPA by using the reverse algorithm, of which 140 (80.9%) were TPPA positive. CONCLUSIONS: Despite the increased false-positive results in populations with a low prevalence of syphilis, the reverse algorithm detected 140 samples with treponemal antibody that went undetected by the traditional algorithm. The reverse algorithm using Mediace TPLA as a screening test is more sensitive for the detection of syphilis.

Canadian Public Health Laboratory Network laboratory guidelines for the use of serological tests (excluding point-of-care tests) for the diagnosis of syphilis in Canada.

Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe. Infections may be sexually transmitted as well as spread from an infected mother to her fetus or through blood transfusions. The laboratory diagnosis of syphilis infection is complex. Because this organism cannot be cultured, serology is used as the principal diagnostic method. Some of the issues related to serological diagnoses are that antibodies take time to appear after infection, and serology screening tests require several secondary confirmatory tests that can produce complex results needing interpretation by experts in the field. Traditionally, syphilis screening was performed using either rapid plasma reagin or Venereal Disease Research Laboratory tests, and confirmed by treponemal tests such as MHA-TP, TPPA or FTA-Abs. Currently, that trend is reversed, ie, most of the laboratories in Canada now screen for syphilis using treponemal enzyme immunoassays and confirm the status of infection using rapid plasma reagin or Venereal Disease Research Laboratory tests; this approach is often referred to as the reverse algorithm. This chapter reviews guidelines for specimen types and sample collection, treponemal and non-treponemal tests utilized in Canada, the current status of serological tests for syphilis in Canada, the complexity of serological diagnosis of syphilis infection and serological testing algorithms. Both traditional and reverse sequence algorithms are recommended and the algorithm used should be based on a combination of local disease epidemiology, test volumes, performance of the proposed assays and available resources.

La syphilis, causée par la bactérie Treponema pallidum sous-espèce pallidum, est une infection connue depuis l'antiquité. Elle a été signalée pour la première fois en Europe, à la fin du XVe siècle. Les infections peuvent être transmises sexuellement, par une mère infectée à son fœtus ou par des transfusions sanguines. Il est difficile de diagnostiquer la syphilis en laboratoire. Puisque cet organisme ne peut pas être mis en culture, la sérologie est la principale méthode diagnostique. Parmi les problèmes liés aux diagnostics sérologiques, soulignons qu'il faut du temps pour que les anticorps fassent leur apparition après l'infection et que les tests de dépistage sérologique doivent s'associer à plusieurs tests de confirmation secondaires qui peuvent produire des résultats complexes devant être interprétés par des experts dans le domaine. Habituellement, la syphilis était dépistée au moyen du test rapide de la réagine plasmatique ou du test Veneral Disease Research Laboratory et était confirmée par les tests tréponémiques comme le MHA-TP, le TP-PA ou le FTA-Abs. Cette tendance s'inverse actuellement, car la plupart des laboratoires du Canada dépistent la syphilis au moyen d'épreuves immunoenzymatiques tréponémiques et confirment le statut de l'infection au moyen du test rapide de la réagine plasmatique ou du test Veneral Disease Reseach Laboratory. Cette approche est souvent désignée par le terme algorithme inversé. Ce chapitre analyse les directives sur les types de prélèvements et la collecte des échantillons, les tests tréponémiques et non tréponémiques utilisés au Canada, le statut actuel des tests sérologiques de la syphilis au Canada, la complexité du diagnostic sérologique d'infection par la syphilis et les algorithmes des tests sérologiques. Tant l'algorithme habituel que l'algorithme inversé sont recommandés, et l'algorithme utilisé devrait tenir compte à la fois de l'épidémiologie locale de la maladie, du volume de tests, de l'exécution des tests proposés et des ressources disponibles.

Syphilis detection using the Siemens ADVIA Centaur Syphilis treponemal assay.

BACKGROUND: Treponemal tests for detecting syphilis should be sufficiently sensitive and specific, especially when used as the first-line method in reverse-algorithm testing. We compared the Siemens ADVIA Centaur® Syphilis assay to 2 other commercial assays in use by the Star-MDC laboratory to evaluate its performance and usability. METHODS: Agreement between the Siemens ADVIA Centaur Syphilis assay, Siemens IMMULITE® 2000 Syphilis Screen, and Biokit bioelisa Syphilis 3.0 assay was evaluated using 1251 patient samples (50 from known positives, 701 from patients referred for syphilis testing, and 500 from pregnant women). Reactive samples (i.e., reactive according to at least two of the three treponemal methods) were further evaluated using Western blot IgG and IgM, and Venereal Disease Research Laboratory (VDRL) testing. RESULTS: Overall, positive and negative agreement was 100% between the Centaur and IMMULITE assays. In this study, overall agreement was 99.92% between either of the Siemens assays and the Biokit assay; positive agreement was 99%, and negative agreement was 100%. Overall, 0.88% (11/1251) of the samples were interpreted as positive/reactive based on the combined positive results by the ADVIA Centaur, IMMULITE 2000, and bioelisa assays; a positive Euroline anti-Treponema pallidum IgM blot; and a VDRL result of ≥1:8. In this study, no false-reactive samples were identified using this method. CONCLUSION: The Centaur Syphilis assay performance is comparable to the other 2 commercial assays.