Evaluation of Serological Tests for the Diagnosis of Syphilis.

Background Syphilis remains a significant public health concern in India. Ensuring the accuracy of diagnostic tests is crucial for effectively managing this disease. Objectives This study aims to assess the detectability of syphilis using commercially available non-treponemal and treponemal tests due to observed discrepancies in test results, which can lead to confusion and anxiety among healthcare providers and patients. Materials and methods We analyzed 2312 serum samples using the rapid plasma reagin (RPR), Treponema pallidum hemagglutination assay (TPHA), enzyme-linked immunosorbent assay (ELISA), and modified TPHA rapid test, interpreting the results according to the manufacturers' instructions. We evaluated the diagnostic accuracy of all four tests. Concordance between the traditional and reverse algorithms was determined by calculating the percentage of agreement and the kappa (κ) coefficient. Results Of the 2312 samples tested, 34 (1.5%) were positive, and 2098 (90.7%) were negative across all four tests. Comparing the test results with clinical diagnosis, TPHA and TP-ELISA showed the highest sensitivity at 96.08%, while RPR demonstrated the highest specificity at 100%. The agreement between the traditional and reverse algorithms was moderate, with a 97.3% agreement and a κ value of 0.53. Conclusion Reliance on a single serological test for syphilis screening presents limitations. A combined approach using both RPR and TPHA tests can more accurately diagnose and confirm syphilis. This combination strategy is cost-effective and relatively simple to implement.

Assessment of a fully automated RPR assay (Mediace RPR) for serological diagnosis and follow-up of syphilis: a retrospective study.

OBJECTIVES: This study assessed the Mediace RPR assay, an automated RPR (aRPR), for syphilis diagnosis and serological follow-up. METHODS: Serums from patients positively screened for syphilis between January 2017 and December 2019 were retrospectively selected. A focus was performed on patients with a serological follow-up after treatment and/or a reinfection. Serums were tested by both manual (mRPR) and aRPR tests. Categorical and Quantitative Agreements (CA and QA), and serological follow-up conclusions were analyzed. RESULTS: 236 serums from 85 patients (99% of male, 66% of HIV-infected) were included. The overall QA was 54.2%. CA was low (79.7%) especially for samples with low RPR titers. No prozone effect was observed. Serological follow-up after treatment led to similar conclusions, although aRPR titers often decreased faster. Over 26 episodes of reinfection, 4 (15.4%) were misdiagnosed with the aRPR. CONCLUSIONS: While the Mediace aRPR presents the advantages of an automated test, its poor sensitivity in low titers may limit its use.

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.

Evaluation of an automated quantitative latex immunoturbidimetric non-treponemal assay for diagnosis and follow-up of syphilis: a prospective cohort study.

Purpose. We evaluated the Sekure rapid plasma reagin (RPR-S) (Sekisui Diagnostics) automated quantitative latex immunoturbidimetric assay performed on the SK500 clinical chemistry system for clinical appropriateness.Methodology. Syphilis-infected individuals and controls were recruited into a prospective cohort study conducted at a sexually transmitted infection clinic in Antwerp, Belgium. Sera collected at diagnosis (baseline) and at 3, 6, 9 and 12 months post-treatment were tested with RPR-S and Macro-Vue RPR card (RPR-C) (Becton Dickinson) assays; RPR-C was considered the reference test. IgG/IgM enzyme immunoassay and Treponema pallidum polA serum PCR results were consulted by discordancy at baseline. Categorical analyses were performed and correlations were assessed with (non)-linear regression. Post-treatment longitudinal serological evolution was evaluated.Results. A total of 463 samples from 120 new syphilis cases from a variety of clinical stages and 30 syphilis-negative controls were tested. Initially, there was a weak correlation between quantitative RPR-C/S (r=0.15). In 70 samples there was a strong suspicion of hook effect. Of these, 57/70 sera were retested with an extra dilution step, resulting in an average 12-fold increase in quantitative RPR-S results. After the extra dilution, the overall qualitative RPR-C/S agreement was 78.89 %, (κ-coefficient: 0.484). Of the 92 discordant samples, 9 were from the baseline visit (RPR-C titre: 1-8), which could have led to possible missed diagnoses using the RPR-S.Conclusions. The sensitivity and accuracy of the RPR-S test requires improvement before it can be used to diagnose syphilis and evaluate treatment efficacy in clinical practice.

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.

Evaluation of a new serological test for syphilis based on chemiluminescence assay in a tertiary care hospital.

CONTEXT: Syphilis is a transfusion transmissible infections and it is mandatory to do serological test for syphilis (STS) on all donor blood samples. STS is usually based on detection of antibodies against the cardiolipin-lecithin antigen or against the Treponema-specific antigen. STS with good sensitivity and specificity helps enhance blood safety and consolidation of STS along with other transfusion transmittable infections such as human immunodeficiency virus, hepatitis-C virus, and hepatitis-B virus helps in reducing the errors and enhances efficiency. AIMS: This study was designed to evaluate the performance of newly introduced VITROS(®) syphilis Treponema pallidum agglutination (TPA) assay based on enhanced chemiluminescence principle for its analytical performance for use as a STS on donor blood samples at a tertiary care health center in National Capital Region, India. MATERIALS AND METHODS: A total of 108 random blood units collected from the donors (both voluntary and replacement donors) and 28 known syphilis sero-reactive samples stored at -20°C, were used to evaluate the performance of VITROS(®) syphilis TPA assay based on enhanced chemiluminescence assay on VITROS(®) ECiQ immunodiagnostics system along with its analytical performance in terms of its sensitivity, precision, cross-reactivity and interference studies. RESULTS: VITROS(®) syphilis TPA showed 100% sensitivity and specificity with precision (20 days study) of <10% co-efficient of variation. There was no cross-reactivity with other viral and auto-immune antibodies. No interference was observed from endogenous interfering substances like free hemoglobin or fats. CONCLUSIONS: Performance of the VITROS(®) syphilis TPA assay meets the requirements for its use as STS in blood bank, thus allowing consolidation with other transfusion transmittable infections screening assay on chemiluminescence platform, which is highly valuable for optimizing workflow and efficiency.

Evaluation of Centaur Syphilis, Immulite Syphilis, and Mediace TPLA for Detecting Treponemal Antibodies

BACKGROUND: We evaluated the efficacy of two chemiluminescence immunoassays that detect treponemal antibodies, Centaur Syphilis and Immulite Syphilis, in comparison with Mediace Treponema pallidum latex agglutination (TPLA). METHODS: The study was conducted in two phases. In the first phase, we tested 1,147 serum samples that were sequentially submitted for routine syphilis serology. In the second phase, we tested a panel of 119 frozen serum samples that had previously tested positive by Mediace RPR. The kappa value, total agreement percentage, and sensitivity and specificity were analyzed. RESULTS: Of the 1,147 random samples, 24 (2.09%) tested positive with Centaur Syphilis, 16 (1.39%) with Immulite Syphilis, and 19 (1.66%) with Mediace TPLA. Of the 119 Mediace RPR-positive samples, 103 (86.6%) tested positive with Centaur Syphilis, 101 (84.9%%) with Immulite Syphilis, and 105 (88.2%) with Mediace TPLA. The percent agreements (kappa values) were 98.8% (0.934) between Centaur Syphilis and Mediace TPLA, 99.0% (0.94) between Immulite Syphilis and Mediace TPLA, and 99.2% (0.955) between Centaur Syphilis and Immulite Syphilis. To measure the sensitivity and specificity of each treponemal test, samples showing agreement in three or four of the tests (three treponemal tests and Mediace-RPR) were regarded as true positive (n=117) or true negative (n=1,142). The respective values for sensitivity and specificity were 100% and 99.6% for Centaur Syphilis, 98.3% and 100% for Immulite Syphilis, and 99.2% and 99.7% for Mediace TPLA. CONCLUSIONS: Results from the three treponemal assays were in good agreement. Greater sensitivity of Centaur Syphilis and greater specificity of Immulite Syphilis were suggested.

Evaluation of Centaur Syphilis, Immulite Syphilis, and Mediace TPLA for Detecting Treponemal Antibodies

BACKGROUND: We evaluated the efficacy of two chemiluminescence immunoassays that detect treponemal antibodies, Centaur Syphilis and Immulite Syphilis, in comparison with Mediace Treponema pallidum latex agglutination (TPLA). METHODS: The study was conducted in two phases. In the first phase, we tested 1,147 serum samples that were sequentially submitted for routine syphilis serology. In the second phase, we tested a panel of 119 frozen serum samples that had previously tested positive by Mediace RPR. The kappa value, total agreement percentage, and sensitivity and specificity were analyzed. RESULTS: Of the 1,147 random samples, 24 (2.09%) tested positive with Centaur Syphilis, 16 (1.39%) with Immulite Syphilis, and 19 (1.66%) with Mediace TPLA. Of the 119 Mediace RPR-positive samples, 103 (86.6%) tested positive with Centaur Syphilis, 101 (84.9%%) with Immulite Syphilis, and 105 (88.2%) with Mediace TPLA. The percent agreements (kappa values) were 98.8% (0.934) between Centaur Syphilis and Mediace TPLA, 99.0% (0.94) between Immulite Syphilis and Mediace TPLA, and 99.2% (0.955) between Centaur Syphilis and Immulite Syphilis. To measure the sensitivity and specificity of each treponemal test, samples showing agreement in three or four of the tests (three treponemal tests and Mediace-RPR) were regarded as true positive (n=117) or true negative (n=1,142). The respective values for sensitivity and specificity were 100% and 99.6% for Centaur Syphilis, 98.3% and 100% for Immulite Syphilis, and 99.2% and 99.7% for Mediace TPLA. CONCLUSIONS: Results from the three treponemal assays were in good agreement. Greater sensitivity of Centaur Syphilis and greater specificity of Immulite Syphilis were suggested.

Establishment and Multicenter Evaluation of a National Reference Panel for Syphilis Antibodies in Korea

BACKGROUND: Establishment of a national reference panel for syphilis antibodies is necessary to evaluate the performance of in-vitro diagnostic tests for syphilis and to verify test quality. This study aimed to establish a national reference panel for syphilis antibodies, to assess the suitability of a panel for non-treponemal and treponemal testing, and to assess the reactivity of the various tests currently in use. METHODS: Treponemal pallidum particle agglutination (TPPA)-positive and -negative fresh frozen plasma samples were obtained. After the fresh frozen plasma was converted to serum by defibrination, the samples were pooled. Two candidate reference standards containing no syphilis antibodies and 10 candidate reference standards containing syphilis antibodies were prepared on the basis of reactivity in the TPPA assay. Candidate reference standards were tested by three laboratories using five non-treponemal tests and four treponemal tests. RESULTS: All three laboratories reported positive non-treponemal test results for the mixed-titer performance panel (MP)/6-MP/12. MP/1, MP/2, and MP/3 were negative for non-treponemal tests. MP/4 and MP/5 were reported either as positive or negative according to the laboratories. All laboratories reported positive TPPA results for MP/3-MP/12 and negative results for MP/1 and MP/2. No significant difference was detected among the treponemal testing results in three laboratories. CONCLUSIONS: We established 12 candidate national reference standards containing various concentrations of syphilis antibodies. A collaborative study using nine tests demonstrated that 12 candidate national reference standards presented consistent results, except a few assays with low sensitivity, and thus could be used as a national reference panel for syphilis antibody testing.

Evaluación de las características funcionales del juego de reactivos VDRL Plus / Evaluation of the functional characteristics of the set of reagents called VDRL Plus

Introducción: la prueba de VDRL (venereal disease research laboratories) es una técnica no treponémica de microfloculación en lámina para la detección cualitativa y semicuantitativa de reaginas plasmáticas. El VDRL Plus es un juego de reactivos que contiene una suspensión antigénica estabilizada (no alcohólica), basada en una mezcla de cardiolipina, colesterol y lecitina en tampón fosfato. Objetivo: determinar un conjunto de parámetros funcionales que caracterizan el desempeño diagnóstico o clínico del juego de reactivo VDRL Plus producido en Centro de Isótopos (CENTIS). Métodos: los parámetros del desempeño diagnóstico evaluados fueron: sensibilidad y especificidad diagnóstica, valores predictivos positivo y negativo, razón de verosimilitud positiva y negativa. Se determinaron además los índices de Youden y de concordancia Kappa. Se emplearon como métodos de referencia TPHA (Treponema pallidum hemagglutination) y RPR (rapid plasma reagin)-carbón producidos en el CENTIS. Se utilizaron muestras de sueros obtenidas en diferentes instituciones de salud de La Habana y el estudio se realizó con dos lotes del producto. Resultados: para los dos lotes evaluados se obtuvieron valores de sensibilidad de 100 porciento y de especificidad diagnóstica de 81 y 84 porciento. Los valores predictivos positivos resultaron de 71 y 75 porciento, y los negativos de 100 porciento. Por su parte, las razones de verosimilitud negativas fueron de 0 porciento y las positivas de 5,3 y 6,3 porciento, para cada lote estudiado. Los índices de Youden obtenidos (0,84 y 0,81) y la concordancia expresada mediante Kappa muestran que existe una adecuada correlación entre los resultados con el método en evaluación y los de referencia. Conclusiones: las características funcionales evaluadas evidencian que el diagnosticador VDRL Plus es apto para el uso previsto y que estas son consistentes entre los lotes estudiados

Introduction: the VDRL test (venereal disease research laboratories) is a no-treponemal slide microaglutination test for the qualitative and semi-quantitative detection of plasma reagins in human serum. The VDRL Plus contains non alcoholic stabilized antigen suspension based in cardiolipin, lecithin and cholesterol in phosphate buffer. Objective: to determine a group of functional parameters in the diagnostic or clinical performance of the VDRL Plus set of reagents produced by the Center of Isotopes (CENTIS). Methods: several parameters, such as, sensitivity, specificity, positive and negative predictive values and positive and negative likelihood ratios were evaluated. Likewised, Youden and Kappa indexes were calculated. Two references methods were employed, that is, TPHA (Treponema pallidum hemagglutination) and RPR-Carbon (rapid plasma reagin)-carbon, both from CENTIS. Serum samples were collected from several health centers in Havana city. Two different product batches were evaluated. Results: the sensitivity value for both evaluated batches was 100 percent and the specificity was 81 and 84 percent. The positives predictive values were 71 and 75 percent and negative predictive value was 100 percent. The positive likelihood ration were 5.3 and 6,3 percent respectively and negative likelihood ration was 0 percent for both batches. The Youden indexes obtained (0.84 and 0.81) and Kappa's indexes showed that there was an adequate correlation between the results obtained and the evaluation and reference methods. Conclusions: the evaluated functional characteristics showed that they are consistent among studied batches and that the VDRL Plus assay is suitable for the intended use

Evaluación de las características funcionales del juego de reactivos VDRL Plus / Evaluation of the functional characteristics of the set of reagents called VDRL Plus

Introducción: la prueba de VDRL (venereal disease research laboratories) es una técnica no treponémica de microfloculación en lámina para la detección cualitativa y semicuantitativa de reaginas plasmáticas. El VDRL Plus es un juego de reactivos que contiene una suspensión antigénica estabilizada (no alcohólica), basada en una mezcla de cardiolipina, colesterol y lecitina en tampón fosfato. Objetivo: determinar un conjunto de parámetros funcionales que caracterizan el desempeño diagnóstico o clínico del juego de reactivo VDRL Plus producido en Centro de Isótopos (CENTIS). Métodos: los parámetros del desempeño diagnóstico evaluados fueron: sensibilidad y especificidad diagnóstica, valores predictivos positivo y negativo, razón de verosimilitud positiva y negativa. Se determinaron además los índices de Youden y de concordancia Kappa. Se emplearon como métodos de referencia TPHA (Treponema pallidum hemagglutination) y RPR (rapid plasma reagin)-carbón producidos en el CENTIS. Se utilizaron muestras de sueros obtenidas en diferentes instituciones de salud de La Habana y el estudio se realizó con dos lotes del producto. Resultados: para los dos lotes evaluados se obtuvieron valores de sensibilidad de 100 porciento y de especificidad diagnóstica de 81 y 84 porciento. Los valores predictivos positivos resultaron de 71 y 75 porciento, y los negativos de 100 porciento. Por su parte, las razones de verosimilitud negativas fueron de 0 porciento y las positivas de 5,3 y 6,3 porciento, para cada lote estudiado. Los índices de Youden obtenidos (0,84 y 0,81) y la concordancia expresada mediante Kappa muestran que existe una adecuada correlación entre los resultados con el método en evaluación y los de referencia. Conclusiones: las características funcionales evaluadas evidencian que el diagnosticador VDRL Plus es apto para el uso previsto y que estas son consistentes entre los lotes estudiados(AU)

Introduction: the VDRL test (venereal disease research laboratories) is a no-treponemal slide microaglutination test for the qualitative and semi-quantitative detection of plasma reagins in human serum. The VDRL Plus contains non alcoholic stabilized antigen suspension based in cardiolipin, lecithin and cholesterol in phosphate buffer. Objective: to determine a group of functional parameters in the diagnostic or clinical performance of the VDRL Plus set of reagents produced by the Center of Isotopes (CENTIS). Methods: several parameters, such as, sensitivity, specificity, positive and negative predictive values and positive and negative likelihood ratios were evaluated. Likewised, Youden and Kappa indexes were calculated. Two references methods were employed, that is, TPHA (Treponema pallidum hemagglutination) and RPR-Carbon (rapid plasma reagin)-carbon, both from CENTIS. Serum samples were collected from several health centers in Havana city. Two different product batches were evaluated. Results: the sensitivity value for both evaluated batches was 100 percent and the specificity was 81 and 84 percent. The positives predictive values were 71 and 75 percent and negative predictive value was 100 percent. The positive likelihood ration were 5.3 and 6,3 percent respectively and negative likelihood ration was 0 percent for both batches. The Youden indexes obtained (0.84 and 0.81) and Kappa's indexes showed that there was an adequate correlation between the results obtained and the evaluation and reference methods. Conclusions: the evaluated functional characteristics showed that they are consistent among studied batches and that the VDRL Plus assay is suitable for the intended use(AU)

Neurosífilis, evaluación de pruebas inmunológicas para su diagnóstico / Immunological test evaluation for neurosyphilis diagnosis

Con el objetivo de correlacionar las pruebas VDRL (Venereal Disease Research Laboratory) y USR (unheated serum reagin) para diagnóstico de neurosífilis, se evaluaron los resultados en 106 líquidos cefalorraquídeos. De 106 líquidos cefalorraquídeos procesados con VDRL y USR, 7,54% fue reactivo por los dos métodos, 90,57% no reactivo por ambos métodos y 1,89% discordante. VDRL y USR clasifican de la misma manera, p no significativa (prueba de Mac Nemar). Si bien la VDRL en líquido cefalorraquídeo es la prueba serológica estándar para neurosífilis, la USR podría ser usada para su diagnóstico, ya que no existe diferencia estadísticamente significativa con la VDRL, es más económica, más práctica y más accesible en el mercado.

The results of 106 cerebrospinal fluids have been evaluated with the aim of correlating the VDRL (Venereal Disease Research Laboratory) and USR (unheated serum reagin) tests for neurosyphilis diagnosis. From 106 cerebrospinal fluids processed with VDRL and USR, 7.54% was reactive by the two methods, 90.57% was nonreactive by both methods and 1.89% was discordant. Mac Nemars test determined that VDRL and USR classified in the same way (not significative p). Although the VDRL in cerebrospinal fluids is the standard serologic test for neurosyphilis, the USR could be used as well for its diagnosis, since it is not significatively different from the statistical point of view with the VDRL; it is less expensive, more practical and more easily available in the market.

Current Status of External Quality Assessment of Syphilis Test in Korea / 대한진단검사의학회지

BACKGROUND: Current status of external quality assessment (EQA) of laboratory tests for syphilis in Korea was analyzed to find out the problems that should be improved in the future. METHODS: Based on the data from the external quality assessment program performed twice a year by the Immunoserology Subcommittee of the Korean Association of Quality Assurance for Clinical Laboratory from the year 2004 to 2006, discordance rates were analyzed according to the test method and commercial kit used. RESULTS: Among the laboratories participating in the EQA program for syphilis test, about 90% of them used non-treponemal tests and about 55% treponemal tests. The non-treponemal tests included RPR (rapid plasma reagin) and VDRL tests used in 88% (363/412) and 11% (45/412), respectively, of the laboratories. The discordance rates were 2.2% for RPR test and 3.6% for VDRL. For the treponemal tests, Treponema pallidum hemagglutination assay (TPHA) was used in 60-76% and Immunochromatography assay (ICA) in about 30% of the laboratories in 2006. A high discordance rate of over 10% was reported in both TPHA and in ICA methods, possibly due to a low titer (1:1 in VDRL) of EQA samples in 2005. Analysis of the accumulated data from year 2004 to 2006 showed that the discordance rates of TPHA, ICA, and FTA-ABS were 4.6%, 3.7%, and 2.7%, respectively. CONCLUSIONS: For syphilis tests, RPR test, TPHA, and ICA are mainly used in Korea. A high discordance rate is still reported in TPHA and ICA, especially when testing samples with a low titer. Further analysis of data and education of laboratory personnel are needed for the improvement of the EQA program.

Evaluation of Performance and False Positivity of Mediace RPR Test that Uses a Chemistry Autoanalyzer / 대한진단검사의학회지

BACKGROUND: We evaluated the performance and false positive rate of Mediace RPR test (Sekisui, Japan), a newly introduced nontreponemal test using a chemistry autoanalyzer. METHODS: The sensitivity of Mediace RPR test was analyzed using sera from 50 patients with syphilis in different stages (8 primary, 7 secondary, and 35 latent), 14 sera positive with fluorescent treponemal antibody absorption (FTA-ABS) IgM, and 74 sera positive with conventional rapid plasma regain (RPR) card test (Asan, Korea) and also positive with Treponema pallidum hemagglutination (TPHA) test or FTA-ABS IgG test. The specificity was analyzed on 108 healthy blood donors. We also performed RPR card test on 302 sera that had been tested positive with Mediace RPR test and also performed TPHA or FTA-ABS IgG test to analyze the false positive rate of Mediace RPR test. A cutoff value of 0.5 R.U. (RPR unit) was used for Mediace RPR test. RESULTS: Mediace RPR test on syphilitic sera of different stages (primary, secondary, and latent stages) and FTA-ABS IgM positive sera showed a sensitivity of 100%, 100%, 82.9% and 100%, respectively. Among the 74 sera positive with conventional RPR card test and TPHA or FTA-ABS IgG test, 55 were positive with Mediace test. The specificity of Mediace RPR test on blood donors was 97.2%. Among the 302 sera positive with Mediace RPR test, 137 sera (45.4%) were negative by RPR card and TPHA/FTA-ABS IgG tests. CONCLUSIONS: Although the sensitivities of Mediace RPR were good for primary and secondary syphilis, due to its high negative rate of Mediace RPR over the conventional RPR positive samples, further studies are necessary whether it can replace conventional nontreponemal test for screening purpose. Moreover, in view of the high false positive rate, positive results by Mediace RPR test should be confirmed with treponemal tests.