title: Evaluation of an IgM/IgG sensitive enzyme immunoassay and the utility of index values for the screening of syphilis infection in a high-risk population.
abstract: BACKGROUND
  Increasing interest in the use of enzyme immunoassays (EIA) for syphilis screening has generated a considerable need for data on the performance of such tests.
  
  
  METHODS
  We compared the performance of 1 EIA, the TREP-SURE EIA to that of the Venereal Disease Research Laboratory (VDRL) and Treponema pallidum particle agglutination assay (TPPA) in the detection of infection with Treponema pallidum. In total, 674 specimens were tested by VDRL and EIA (356 VDRL-nonreactive and 318 VDRL-reactive). All specimens that were found to be reactive by either the VDRL or EIA were subsequently analyzed by TPPA.
  
  
  RESULTS
  We found that the TREP-SURE EIA was marginally less sensitive than the VDRL test for screening, but was significantly more specific. All EIA-TPPA discordant specimens were analyzed by multiple tests, including Immunoglobulin M- and G-specific Western blots and an IgM-specific EIA. Signal-to-cutoff ratios (index values) generated by the TREP-SURE EIA were also investigated. It was found that these values may be instructive regarding the interpretation of test results, as they were found to correlate strongly with the probability of positivity on a TPPA assay. Specimens that reacted positively on the EIA with very high index values were found overwhelmingly to be reactive by TPPA, perhaps obviating the need for the testing of most EIA positive specimens with a secondary treponemal test.
  
  
  CONCLUSIONS
  An IgM/IgG sensitive EIA would be an effective alternative to VDRL for syphilis screening. Using the EIA index values may provide additional, helpful information to the diagnostic process.
authors.affiliation: San Francisco Department of Public Health, San Francisco, CA, USA.
authors.forename: Ernest H
authors.initials: EH
authors.lastname: Wong
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Klausner
authors.forename: Gloria
authors.initials: G
authors.lastname: Caguin-Grygiel
authors.forename: Carmela
authors.initials: C
authors.lastname: Madayag
authors.forename: Kim O
authors.initials: KO
authors.lastname: Barber
authors.forename: Julia S
authors.initials: JS
authors.lastname: Qiu
authors.forename: Sally
authors.initials: S
authors.lastname: Liska
authors.forename: Mark W
authors.initials: MW
authors.lastname: Pandori
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D005260:Female; D018451:Homosexuality, Male; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000592:standards*; D011933:Reagent Kits, Diagnostic; D012306:Risk; D012680:Sensitivity and Specificity; D013587:Syphilis / Q000175:diagnosis*; D013588:Syphilis Serodiagnosis; D014210:Treponema pallidum / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011933:Reagent Kits, Diagnostic