Journal of clinical microbiology 2017 09 06() pii 10.1128/JCM.00966-17
A syphilis diagnosis is often aided by the detection of treponemal and non-treponemal antibodies. Automated treponemal antibody detection systems enable high-volume clinical laboratories to perform syphilis screening at a faster pace with lower labor costs. The Lumipulse G TP-N chemiluminescent immunoassay is an automated system that qualitatively detects IgG and IgM antibodies against Treponema pallidum antigens in human serum and plasma. To assess performance characteristics and workflow efficiency, the Lumipulse G TP-N assay was compared to the Bioplex 2200 Syphilis IgG multiplex flow immunoassay. Among the 4,134 routine and HIV samples tested by both automated assays, the percent agreement was excellent at 99.0% (95% CI 98.6%-99.2%; κ 0.89), with the Lumipulse G TP-N having a faster time to first and subsequent results. All reactive syphilis screening results were reflexed to rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TP⋅PA) testing (n= 231). The RPR reactive samples (n= 82) showed complete concordance with both automated assays, while the TP⋅PA assay displayed some discrepancies. The positive and negative percent agreement (PPA, NPA) between the TP⋅PA and Lumipulse G TP-N test, was 98.9% and 77.3%, respectively. The Bioplex 2200 Syphilis IgG displayed a similar PPA (100%), but substantially lower NPA (15.9%). Patient chart reviews of discrepant results suggest the Lumipulse G TP-N assay produced 27 fewer false-reactive results, and can reduce the amount of additional confirmatory RPR and TP⋅PA testing. The analogous performance characteristics between the two automated systems indicate the Lumipulse G TP-N assay is suitable for high-throughput syphilis screening.