[Comparison of quantitative results among two automated Rapid Plasma Reagin (RPR) assays and a manual RPR test].
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.
Kim
Yeong Sic
YS
Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Lee
Jehoon
J
Lee
Hae Kyung
HK
Kim
Hyunjung
H
Kwon
Hi Jeong
HJ
Min
Ki Ouk
KO
Seo
Eun Joo
EJ
Kim
Soo-Young
SY
D001331:Automation; D005260:Female; D006801:Humans; D008297:Male; D011933:Reagent Kits, Diagnostic; D011935:Reagins / Q000097:blood*; D012680:Sensitivity and Specificity; D013587:Syphilis / Q000175:diagnosis*; D013588:Syphilis Serodiagnosis / Q000379:methods*; D014210:Treponema pallidum
D011933:Reagent Kits, Diagnostic; D011935:Reagins