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Canadian Journal of Infectious Diseases and Medical Microbiology
Volume 26, Supplement A, Pages 13A-17A
CPHLN Laboratory Guidelines

Canadian Public Health Laboratory Network Laboratory Guidelines for the Use of Direct Tests to Detect Syphilis in Canada

Raymond SW Tsang,1 Muhammad Morshed,2,3 Max A Chernesky,4 Gayatri C Jayaraman,5 and Kamran Kadkhoda6,7

1National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
2BC Public Health Microbiology and Reference Laboratory, University of British Columbia, Vancouver, British Columbia, Canada
3Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
4McMaster University, Hamilton, Canada
5Centre for Communicable Diseases and Infection Control, Public Health Agency of Canada, Ottawa, Ontario, Canada
6Cadham Provincial Laboratory, University of Manitoba, Winnipeg, Manitoba, Canada
7Department of Medical Microbiology & Infectious Diseases and Department of Immunology, University of Manitoba, Winnipeg, Manitoba, Canada

Copyright © 2015 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Treponema pallidum subsp. pallidum and/or its nucleic acid can be detected by various methods such as microscopy, rabbit infectivity test or polymerase chain reaction (PCR) tests. The rabbit infectivity test for T. pallidum, although very sensitive, has been discontinued from most laboratories due to ethical issues related to the need for animal inoculation with live T. pallidum, the technically demanding procedure and long turnaround time for results, thus making it impractical for routine diagnostic use. Dark-field and phase-contrast microscopy are still useful at clinic- or hospital-based laboratories for near-bedside detection of T. pallidum in genital, skin or mucous lesions although their availability is decreasing. The lack of reliable and specific anti-T. pallidum antibodies and its inferior sensitivity to PCR may explain why the direct fluorescent antibody test for T. pallidum is not widely available for clinical use. Immunohistochemical staining for T. pallidum also depends on the availability of specific antibodies, and the method is only applicable for histopathological examination of biopsy and autopsy specimens necessitating an invasive specimen collection approach. With recent advances in molecular diagnostics, PCR is considered to be the most reliable, versatile and practical for laboratories to implement. In addition to being an objective and sensitive test for direct detection of Treponema pallidum subsp. pallidum DNA in skin and mucous membrane lesions, the resulting PCR amplicons from selected gene targets can be further characterized for antimicrobial (macrolide) susceptibility testing, strain typing and identification of T. pallidum subspecies.