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P759 Evaluation of the fully automated bio-rad bioplex 2200 syphilis total & RPR antibody detection assay
  1. Vincent Boissonneault1,
  2. Valérie Martel-Laferrière1,
  3. Bouchra Serhir2,
  4. Claude Fortin1
  1. 1Centre Hospitalier de l’Université de Montréal, Departement De Microbiologie Infectiologie, Montreal, Canada
  2. 2Institut National de Santé Publique du Québec, Montréal, Canada


Background Laboratory diagnostic of syphilis is based on both treponemal and non-treponemal assays. While automated treponemal assays are available, non-treponemal antibody testing continue to require extensive hands on time. The BioPlex 2200 Syphilis Total & RPR assay by Bio-Rad Laboratories is a fully automated assay that detects both treponemal and non-treponemal antibodies with on board RPR titer capability.

Methods We compared the BioPlex Total & RPR assay with the BiopPex IgG assay and with the Wampole Impact RPR card test for the treponemal and non-treponemal antibodies detection respectively. A total of 504 prospective sera sent to our laboratory for syphilis testing were tested with both BioPlex assays to establish agreement of treponemal results. Also, a panel of 52 sera with known titer values was provided by our reference laboratory. These sera were tested with the BioPlex Total & RPR assay and the manual Wampole RPR card to compare titer results, using essential agreement within 1 dilution range and correlation of log2 transformed titer values with Spearman coefficient.

Results Of the 504 sera tested, 112 were positive for treponemal antibodies with BioPlex Total & RPR and 109 with BioPlex IgG. Positive, negative and overall agreements were 95% (104/109)(95% CI [89%, 98%]), 98% (387/395)(95% CI [96%, 99%]) and 97% (491/504)(95% CI [95%, 99%]) respectively for these sera. Essential agreement within 1 dilution of quantitative RPR titer results for the 52 sera panel was 90% and the Spearman correlation coefficient of titers obtained with the two assays was 0.926 with a p <0.001.

Conclusion The BioPlex 2200 Syphilis Total & RPR assay is a fully automated assay that compares favorably with the BioPlex 2200 Syphilis IgG assay and that yields non treponemal titers that correlates favorably with a traditional manual RPR card test. Reliable automated non treponemal assays are needed.

Disclosure No significant relationships.

  • syphilis

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