title: Assessment of a real-time PCR test to diagnose syphilis from diverse biological samples.
abstract: OBJECTIVE
  To investigate the contribution of a real-time PCR assay for the detection of Treponema pallidum in various biological specimens with the secondary objective of comparing its value according to HIV status.
  
  
  METHODS
  Prospective cohort of incident syphilis cases from three Swiss hospitals (Geneva and Bern University Hospitals, Outpatient Clinic for Dermatology of Triemli, Zurich) diagnosed between January 2006 and September 2008. A case-control study was nested into the cohort. Biological specimens (blood, lesion swab or urine) were taken at diagnosis (as clinical information) and analysed by real-time PCR using the T pallidum 47 kDa gene.
  
  
  RESULTS
  126 specimens were collected from 74 patients with primary (n = 26), secondary (n = 40) and latent (n = 8) syphilis. Among primary syphilis, sensitivity was 80% in lesion swabs, 28% in whole blood, 55% in serum and 29% in urine, whereas among secondary syphilis, it was 20%, 36%, 47% and 44%, respectively. Among secondary syphilis, plasma and cerebrospinal fluid were also tested and provided a sensitivity of 100% and 50%, respectively. The global sensitivity of T pallidum by PCR (irrespective of the compartment tested) was 65% during primary, 53% during secondary and null during latent syphilis. No difference regarding serology or PCR results was observed among HIV-infected patients. Specificity was 100%.
  
  
  CONCLUSIONS
  Syphilis PCR provides better sensitivity in lesion swabs from primary syphilis and displays only moderate sensitivity in blood from primary and secondary syphilis. HIV status did not modify the internal validity of PCR for the diagnosis of primary or secondary syphilis.
authors.affiliation: HIV Care Unit, Division of Infectious Diseases, Geneva's University Hospitals and School of Medicine, Geneva, Switzerland. angele.gayet-ageron@hcuge.ch
authors.forename: A
authors.initials: A
authors.lastname: Gayet-Ageron
authors.forename: B
authors.initials: B
authors.lastname: Ninet
authors.forename: L
authors.initials: L
authors.lastname: Toutous-Trellu
authors.forename: S
authors.initials: S
authors.lastname: Lautenschlager
authors.forename: H
authors.initials: H
authors.lastname: Furrer
authors.forename: V
authors.initials: V
authors.lastname: Piguet
authors.forename: J
authors.initials: J
authors.lastname: Schrenzel
authors.forename: B
authors.initials: B
authors.lastname: Hirschel
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D017963:Azithromycin / Q000627:therapeutic use; D004269:DNA, Bacterial / Q000302:isolation & purification*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004812:Epidemiologic Methods; D005260:Female; D006679:HIV Seropositivity; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D017423:Sequence Analysis, RNA; D013587:Syphilis / Q000097:blood / Q000175:diagnosis* / Q000652:urine; D013588:Syphilis Serodiagnosis; D014210:Treponema pallidum / Q000235:genetics* / Q000302:isolation & purification; D047568:Unsafe Sex
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017963:Azithromycin