Novel point-of-care test for simultaneous detection of nontreponemal and treponemal antibodies in patients with syphilis.

We describe a point-of-care immunochromatographic test for the simultaneous detection of both nontreponemal and treponemal antibodies in the sera of patients with syphilis that acts as both a screening and a confirmatory test. A total of 1,601 banked serum samples were examined by the dual test, and the results were compared to those obtained using a quantitative rapid plasma reagin (RPR) test and the Treponema pallidum passive particle agglutination (TP-PA) assay. Compared to the RPR test, the reactive concordance of the dual test nontreponemal line was 98.4% when the RPR titers of sera were >= 1:2 and the nonreactive concordance was 98.6%. Compared to the TP-PA assay, the reactive and nonreactive concordances of the treponemal line were 96.5% and 95.5%, respectively. These results indicate that the dual test could be used for the serological diagnosis of syphilis in primary health care clinics or resource-poor settings and therefore improve rates of treatment where patients may fail to return for their laboratory results.