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.
Automation ; Female ; Humans ; Male ; Reagent Kits, Diagnostic ; Reagins/*blood ; Sensitivity and Specificity ; Syphilis/*diagnosis ; Syphilis Serodiagnosis/*methods ; Treponema pallidum

OBJECTIVETo investigate the incidence of seroresistance of syphilis and analyze its relevant factors.

METHODSThe clinical data of 131 patients with syphilis were retrospectively analyzed. The incidence of seroresistance was investigated and the correlation between seroresistance and factors including age, gender, original titer, disease course, and medications were analyzed.

RESULTSThe incidence of seroresistance was not significantly different among patients with different ages and genders, but was significantly different among patients with different disease courses, antibody titers, and medications. Patients with a baseline serum rapid plasma reagin (RPR) titer of greater than 1: 8, a latent course, or a macrolide therapy history had higher incidences of seroresistance (i. e., 61%, 45.6%, and 72.7% respectively) than those who had a lower RPR titer, a primary course, or a benzathine penicillin therapy history.

CONCLUSIONSyphilis patients with a high baseline RPR titer, a latent course, and a macrolides therapy are prone to be seroresistant.

Adolescent ; Adult ; Aged ; Female ; Humans ; Macrolides ; therapeutic use ; Male ; Middle Aged ; Reagins ; blood ; Syphilis ; blood ; diagnosis ; drug therapy ; immunology ; Syphilis Serodiagnosis ; methods ; Young Adult

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.
Algorithms ; Anti-Bacterial Agents/therapeutic use ; Humans ; Latex Fixation Tests ; Reagins/blood ; Syphilis/*diagnosis/drug therapy/microbiology ; Treponema pallidum/isolation & purification

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.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Agglutination ; False Positive Reactions ; Female ; Humans ; Immunoglobulin G/analysis ; Immunoglobulin M/analysis ; Latex Fixation Tests ; Male ; Middle Aged ; Reagent Kits, Diagnostic ; Reagins/*blood ; Syphilis/*diagnosis ; Syphilis Serodiagnosis/*methods ; Treponema pallidum/*immunology/isolation & purification