Korean J Lab Med.  2009 Aug;29(4):331-337. 10.3343/kjlm.2009.29.4.331.

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

• Kim YS
• Lee J
• Lee HK
• Kim H
• Kwon HJ
• Min KO
• Seo EJ
• Kim SY

• KMID: 1096927
• DOI: http://doi.org/10.3343/kjlm.2009.29.4.331

Abstract

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.

Keyword

Rapid Plasma Reagin; RPR titer; Prozone effect

MeSH Terms

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

Figure

• 

  Fig. 1. Measurement of reagin antibody using two automated RPR assay kits, Mediace RPR and HBi Auto RPR. Serial two-fold diluted samples were tested and the RPR titers (RPR card test) of the undiluted samples were 1:64 (A), 1:32 (B), 1:16 (C and D), 1:8 (E), and 1:2 (F).

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