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Journal of Clinical Microbiology, June 2009, p. 1668-1673, Vol. 47, No. 6
0095-1137/09/$08.00+0 doi:10.1128/JCM.02392-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Division of Pathogenic Neisseria, Syphilis Diagnostics, and Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba,1 Alberta Health and Wellness, Edmonton, Alberta,2 Alberta Provincial Laboratory for Public Health, Edmonton, Alberta,3 Calgary STD Clinic, Calgary, Alberta,4 Alberta Health Services—Capital Health, STD Centre, Edmonton, Alberta, Canada5
Received 13 December 2008/ Returned for modification 26 January 2009/ Accepted 26 March 2009
Although detection of Treponema pallidum DNA in whole-blood specimens of syphilis patients has been reported, it is uncertain at what stage of the disease such specimens are most suitable for the molecular diagnosis of syphilis. Also, few studies have directly compared the different gene targets for routine laboratory diagnostic usage in PCR assays. We examined 87 specimens from 68 patients attending two urban sexually transmitted disease clinics in Alberta, Canada. PCR was used to amplify the T. pallidum tpp47, bmp, and polA genes as well as a specific region of the 23S rRNA gene linked to macrolide antibiotic susceptibility. In primary syphilis cases, PCR was positive exclusively (75% sensitivity rate) in ulcerative swabs but not in blood specimens, while in secondary syphilis cases, 50% of the blood specimens were positive by PCR. Four out of 14 (28.6%) of our PCR-positive syphilis cases were found to be caused by an azithromycin-resistant strain(s). Our results confirmed that swabs from primary ulcers are the specimens of choice for laboratory diagnostic purposes. However, further research is required to determine what specimen(s) would be most appropriate for molecular investigation of syphilis in secondary and latent syphilis.
Published ahead of print on 1 April 2009.
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