title: Comparison of automated treponemal and nontreponemal test algorithms as first-line syphilis screening assays.
abstract: BACKGROUND
  Automated Mediace Treponema pallidum latex agglutination (TPLA) and Mediace rapid plasma reagin (RPR) assays are used by many laboratories for syphilis diagnosis. This study compared the results of the traditional syphilis screening algorithm and a reverse algorithm using automated Mediace RPR or Mediace TPLA as first-line screening assays in subjects undergoing a health checkup.
  
  
  METHODS
  Samples from 24,681 persons were included in this study. We routinely performed Mediace RPR and Mediace TPLA simultaneously. Results were analyzed according to both the traditional algorithm and reverse algorithm. Samples with discordant results on the reverse algorithm (e.g., positive Mediace TPLA, negative Mediace RPR) were tested with Treponema pallidum particle agglutination (TPPA).
  
  
  RESULTS
  Among the 24,681 samples, 30 (0.1%) were found positive by traditional screening, and 190 (0.8%) by reverse screening. The identified syphilis rate and overall false-positive rate according to the traditional algorithm were lower than those according to the reverse algorithm (0.07% and 0.05% vs. 0.64% and 0.13%, respectively). A total of 173 discordant samples were tested with TPPA by using the reverse algorithm, of which 140 (80.9%) were TPPA positive.
  
  
  CONCLUSIONS
  Despite the increased false-positive results in populations with a low prevalence of syphilis, the reverse algorithm detected 140 samples with treponemal antibody that went undetected by the traditional algorithm. The reverse algorithm using Mediace TPLA as a screening test is more sensitive for the detection of syphilis.
authors.affiliation: Department of Laboratory Medicine, Dongguk University Ilsan Hospital, Goyang, Korea. hjhuh@duih.org.
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Huh
authors.affiliation: Department of Laboratory Medicine, Dongguk University Ilsan Hospital, Goyang, Korea.
authors.forename: Jae Woo
authors.initials: JW
authors.lastname: Chung
authors.affiliation: Department of Internal Medicine, Dongguk University Ilsan Hospital, Goyang, Korea.
authors.forename: Seong Yeon
authors.initials: SY
authors.lastname: Park
authors.affiliation: Department of Laboratory Medicine, Dongguk University Ilsan Hospital, Goyang, Korea.
authors.forename: Seok Lae
authors.initials: SL
authors.lastname: Chae
mesh_terms: D000465:Algorithms; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D006801:Humans; D007841:Latex Fixation Tests; D011935:Reagins / Q000097:blood; D013587:Syphilis / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D014210:Treponema pallidum / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D011935:Reagins
keywords: Automated RPR; Automated TPLA; Reverse algorithm; Syphilis; Syphilis screening algorithm