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 Quantitative Results among Two Automated Rapid Plasma Reagin (RPR) Assays and a Manual RPR Test / 대한진단검사의학회지

BACKGROUND: We compared two automated Rapid Plasma Reagin (RPR) assay kits with a manual RPR assay kit to evaluate the possibility of using the two automated RPR assays as an alternative to the manual RPR assay for a quantitative monitoring. METHODS: One hundred eighty-five samples were analyzed, including 16 sera from patients with primary, secondary, and latent syphilis. Measured RPR unit (R.U.) values of two automated RPR assay kits, Mediace RPR (Sekisui Chemical Co., Ltd, Japan) and HBi Auto RPR (HBI Co., Ltd, Korea), were compared with the RPR titers of Macro-Vue RPR card test (Becton Dickinson BD Microbiology systems, USA). As a confirmatory test, Anti-Treponema pallidum EUROLINE WB (IgG) and Anti-Treponema pallidum EUROLINE WB (IgM) (Euroimmun, Germany) were used. RESULTS: There was a prozone effect with Mediace RPR at RPR titer (card test) of 1:16, but not with HBi Auto RPR. The R.U. values of the two automated RPR assays did not show proportional increase to the RPR titer. Agreement between manual RPR and two automated RPR assay kits, Mediace RPR assay and HBi Auto RPR assay, were 83.8% and 83.2%, respectively. CONCLUSIONS: The two automated RPR assay kits could not be used as an alternative to manual RPR test for quantitative analysis of RPR titer. As Mediace RPR shows a prozone effect at relatively low RPR titer, caution is needed in the interpretation of the measured values.

Analysis of Positive Results in Mediace Rapid Plasma Reagin and Treponema pallidum Latex Agglutination as the Automated Syphilis Test / 대한진단검사의학회지

BACKGROUND: We compared the results of automated and quantitative methods for the diagnosis of syphilis, Mediace Rapid Plasma Reagin (RPR) and Mediace Treponema pallidum Latex Agglutination (TPLA) (Sekisui Chemical Co., Ltd, Japan) with those of conventional methods. METHODS: Sera from 3,896 persons who had health checkups between December 2005 and November 2006 were included in the evaluation of positive rates and biological false positives (BFP) for Mediace RPR and TPLA. In addition, 134 patients' sera positive for automated Mediace RPR or TPLA were tested for VDRL and TPHA. Discrepancies between TPLA and TPHA results were confirmed by the RecomBlot Treponemal IgG/IgM (Mikrogen GmbH, Germany). Automated Mediace RPR and TPLA were performed using the Hitachi 7600 chemistry autoanalyzer (Hitachi, Japan). Samples with positive Mediace RPR and negative TPLA results were defined as BFP. RESULTS: Positive rate of automated Mediace RPR was 0.23% (9/3,896). BFP of the Mediace RPR was 0.18%. Positive rate of automated TPLA was 1.62% (37/2,284). Among the 134 patients' sera, 33 (24.6%) showed a discrepancy between conventional VDRL and automated Mediace RPR results: Among 31 Mediace RPR(+)/VDRL(-) sera, 13 were positive and 18 were negative for TPLA. The remaining 2 sera of discrepancy with Mediace RPR(-)/VDRL(+) were all positive for TPLA. There were seven sera that showed a discrepancy between automated TPLA and TPHA results: Two sera with Mediace RPR(+)/TPLA(-)/TPHA(+) showed negative recomBlot Treponemal IgG/IgM results, and among five sera with TPLA(+)/TPHA(-), three demonstrated IgG or IgM by recomBlot Treponemal IgG/IgM. CONCLUSIONS: The results of comparison data demonstrated that automated TPLA results had a high concordance with recomBlot Treponemal IgG/IgM results. Moreover, there are additional advantages of automated methods such as quantitative detection, low infection risk, and no influence by human handling.

Prevalencia de anticuerpos virales y reaginas luéticas en donadores de sangre de un hospital / Prevalence of viral antibodies and serology for syphilis in blood donors from a hospital

Objetivo. Establecer la prevalencia de anticuerpos virales y reaginas luéticas en una población de donadores voluntarios. Sitio. Un hospital general de tercer nivel del ISSSTE en la ciudad de Morelia, estado de Michoacán. Desde 1986 es obligatorio en los bancos de sangre de México, investigar en todos los donadores la presencia de anticuerpos contra el virus de la inmunodeficiencia humana (anti-VIH), antígeno de superficie del virus de la hepatitis B (Ags VHB) y reaginas luéticas (RPR); y desde 1993, es también obligatorio determinar anticuerpos contra el virus de la hepatitis C (anti-VHC). Material y métodos. En siete años (01/01/90 a 31/12/96) se obtuvieron 10,077 muestras de donadores voluntarios sanos para la determinación de anti-VIH, AgsVHB y RPR. De 01/07/92 a 31/12/96 se colectaron 7,256 muestras para investigación de anti-VHC. Resultados. Fueron positivos 19 donadores para anti-VIH (0.18 por ciento), 34 para AgsVHB (0.33 por ciento), 12 para RPR (0.11 por ciento) y 22 para anti-VHC (0.30 por ciento). Estas tasas son similares a las de otros bancos de sangre mexicanos

Inmunoglobulina E (IgE) en sangre del cordón umbilical de recién nacidos con antecedentes de atopia familiar / Imnumeglobulin E (IgE) in umbilical cord blood of newborn with family atopy antecedent

Se determinaron los valores de IgE en sangre del cordón en un grupo de recién nacidos con antecedentes atópicos familiares y un grupo control y sin antecedentes familiares de atopia. Los niveles de IgE en sangre del cordón, mayores de 0,7 UI/ml son considerados como índice predictivo de alergia, especialmente cuando existen antecedentes familiares de alergia y/o el individuo es sometido a sobrecarga de alergenos. Se estudiaron 80 recién nacidos, 40 del grupo experimental y 40 del grupo control, determinándose en ambos grupos concentraciones de IgE (UI/ml, edad gestacional entre 37 y 42 semanas, sexo, peso entre 2500 y más de 3000 gms, y atopia familiar más frecuente relacionada con los niveles de IgE) a concentración de IgE en sangre del cordón, en ambos grupos, fue mayor de 0,7 UI/ml. En relación a las variables edad gestional, peso, y sexo, los valores de IgE no presentaron diferencias significativas. Con respecto a los antecedentes de atopia familiar y los niveles de IgE, la muestra se distribuyó de la siguiente manera, asma con 23 casos (95,83 por ciento), rinitis alérgica con 21 (95,45 por ciento), dermatitis atópica, 4 casos (100 por ciento) y para la urticaria 2 casos (100 por ciento), del total de pacientes en este grupo de atopia familiar 3,85 por ciento presentó cifras de IgE inferiores a 0.7 UI/ml