title: Point-of-care treponemal tests for neurosyphilis diagnosis.
abstract: BACKGROUND
  The laboratory diagnosis of neurosyphilis rests upon identifying cerebrospinal fluid (CSF) abnormalities, including CSF-Venereal Disease Research Laboratory (VDRL) reactivity. The CSF-VDRL may not be available in the parts of the world where neurosyphilis is most common. Treponemal immunochromatographic strip tests (ICSTs) have been developed as point-of-care tests on blood for syphilis diagnosis in resource-limited settings.
  
  
  METHODS
  We optimized 3 commercial ICSTs for performance on CSF and tested CSF samples from 217 patients with syphilis. The Syphicheck-WB test (Qualpro Diagnostics, Goa, India; "Syphicheck") was chosen for further study based on agreement with CSF-VDRL test results. We determined CSF-Syphicheck titers for 152 samples. We modified the CSF-Syphicheck for point-of-care testing in a US sexually transmitted diseases clinic and compared results on 102 paired centrifuged and uncentrifuged CSF samples obtained in the laboratory to the results obtained at point of care; results of samples diluted 1:4 were compared in a subset.
  
  
  RESULTS
  The diagnostic sensitivity of a reactive CSF-Syphicheck (62%-64%) and the diagnostic specificity of a CSF-Syphicheck titer at or above 1:4 (79%-81%) were equivalent to the CSF-VDRL (54%-69% sensitivity, 73%-75% specificity) for laboratory and clinical neurosyphilis diagnoses. The CSF-Syphicheck normalized after neurosyphilis therapy similarly to the CSF-VDRL. The modified CSF-Syphicheck performed well at the point of care, albeit with better performance on cell-free compared with uncentrifuged CSF.
  
  
  CONCLUSIONS
  Cerebrospinal fluid treponemal ICSTs hold promise for point-of-care neurosyphilis diagnosis in regions where the CSF-VDRL is not available. Further study should address the performance of CSF ICSTs in resource-limited settings.
authors.affiliation: From the Department of Neurology, University of Washington, Seattle, WA.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Ho
authors.forename: Lauren C
authors.initials: LC
authors.lastname: Tantalo
authors.forename: Trudy
authors.initials: T
authors.lastname: Jones
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Sahi
authors.forename: Christina M
authors.initials: CM
authors.lastname: Marra
mesh_terms: D002846:Chromatography, Affinity; D019411:Clinical Laboratory Techniques; D005260:Female; D006801:Humans; D008297:Male; D009494:Neurosyphilis / Q000097:blood / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D019095:Point-of-Care Systems; D012680:Sensitivity and Specificity; D013588:Syphilis Serodiagnosis / Q000379:methods*; D014210:Treponema pallidum / Q000302:isolation & purification*