Evaluation of the BioPlex 2200 syphilis total screen (IgG/IgM) with reflex to an automated rapid plasma reagin test.

BACKGROUND: We evaluated the recently FDA cleared BioPlex 2200 Syphilis Total Screen and automated rapid plasma reagin (RPR) assay for the detection of total (IgG/IgM) treponemal and non-treponemal antibodies in the reverse syphilis algorithm. METHODS: Prospectively submitted samples (n = 885) were assayed by both the IgG/IgM BioPlex Syphilis Screen and the original IgG BioPlex Syphilis Screen. The IgG screen reactive samples were reflexed to traditional RPR, and IgG/IgM screen reactive samples were reflexed to the automated RPR. Nonreactive RPR samples were tested by the Treponemal Pallidum Particle Agglutination test (TP-PA). Additional samples were collected (n = 404 total samples) to directly compare the automated and traditional RPR assays with each other. RESULTS: The sensitivity and specificity of the IgG/IgM screen with automated RPR was 95.6% (95% confidence interval [CI] 87.0-99.1) and 99.6% (CI 99.2-99.8) while the sensitivity and specificity of the BioPlex IgG screen with traditional RPR was 97.8% (CI 89.1-99.9) and 99.3% (CI 98.8-99.4). The sensitivity and specificity of the BioPlex RPR compared with traditional RPR was 95.8% (CI 93.9-97.0) and 94.1% (CI 89.4-91.1) and 95.3% (CI 92.6-97.1). The mean of the titer differences between the BioPlex RPR and the traditional RPR was 1.0 ± 0.9 SD titers. CONCLUSION: The addition of the detection of treponemal IgM antibodies to the IgG/IgM screen did not significantly affect the sensitivity and specificity compared to the original IgG screen. However, the addition of the comparable BioPlex RPR assay to the instrumentation significantly reduces the overall labor of syphilis screening and confirmation.

Anti-ENA antibody profiles in patients with hepatitis C virus infection.

BACKGROUND: The presence of antinuclear antibodies (ANA) has been described following hepatitis C virus (HCV). Very few studies have investigated the presence of anti-extractable nuclear antigens (ENA) in HCV infection. METHODS: The aim of this study was to assess the prevalence of ENA antibodies in 100 patients with HCV infection compared to the prevalence of ENA antibodies in 100 healthy control patients. Sera from patients were tested for ENA using a multiplex microbead immunoassay. Sera positive for ENA were subsequently tested for ANA using an indirect immunofluorescence assay and titered if positive. RESULTS: Fourteen (14%) of the 100 patients with HCV infection had anti-ENA antibodies: four each showed anti-SSA antibodies and anti-dsDNA antibodies, three each had RNP antibodies and Scl-70 antibodies, and one each had anti-SSB, centromere B, Sm, and Sm/RNP antibodies. Ten of the 14 patients positive for anti-ENA were positive by indirect immunofluorescence staining (IFA) with titers ranging from 1:40 to 1:160. Five had antinuclear patterns, one had combined antinuclear and cytoplasmic patterns, and four only had a cytoplasmic pattern. Three of the 100 healthy control patients had ANA positive titers (1:80 and 1:320) and anti-ENA antibodies: one anti-Scl-70 and two anti-RNP. CONCLUSION: The prevalence of anti-ENA antibodies was significantly higher in the patients with HCV infections than in the healthy controls. Other studies of anti-ENA profiles in patients with HCV infection have identified similar patterns of positivity for anti-SSA, anti-SSB, anti-dsDNA, anti-RNP, anti- Sm/RNP, Scl-70, centromere B, and anti-Sm.

Performance Characteristics of the Reverse Syphilis Screening Algorithm in a Population With a Moderately High Prevalence of Syphilis.

OBJECTIVES: With the recent introduction of automated treponemal tests, a new reverse syphilis algorithm has been proposed and now used by many clinical laboratories. We analyzed the impact of instituting the reverse screening syphilis algorithm in a laboratory that serves a geographic area with a moderately high prevalence of syphilis infection. METHODS: Serum samples sent for syphilis testing were tested using a treponemal enzyme immunoassay (EIA) as the screening assay. EIA reactive samples were tested by rapid plasma reagin (RPR) and titered to end point if reactive. RPR nonreactive samples were analyzed by the Treponema pallidum particle agglutination test (TP-PA). Pertinent medical records were reviewed for false-reactive screens and samples with evidence of past syphilis infection. RESULTS: Among 10,060 patients tested, 502 (5%) were reactive on the initial EIA screen. The RPR was reactive in 150 (1.5%). TP-PA testing determined that 103 (1.0%) were falsely reactive on initial EIA screen. The reverse screening algorithm, however, identified 242 (2.4%) with evidence of latent, secondary, or past syphilis, 21 of whom had no or unknown prior treatment with antibiotics. CONCLUSIONS: Despite a 1.0% false-reactive rate, the reverse syphilis algorithm detected 21 patients with possible latent syphilis that may have gone undetected by traditional syphilis screening.