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Giornale Italiano di Dermatologia e Venereologia 2004 February;139(1):75-80


language: English, Italian

Polymerase chain reaction: a useful adjunct to the diagnosis of syphilis. Technical note and preliminary results

Alessi E., Ghislanzoni M., Scioccati L., Venegoni L., Merlo V., Cusaro C., Cusini M.

Institute of Dermatological Sciences University of Milan, IRCCS “Maggiore” Hospital, Milan, Italy


Aim. Dark-field mycroscopy is still considered the standard test of choice to demonstrate Treponema pallidum (TP) in exudates of mucocutaneous lesions of early syphilis. However, a new method has recently become available, the detection of TP DNA by polymerase chain reaction (TP PCR method). This new test has already been applied to analyze other biological materials. The aim of this study is to report the results obtained from 70 clinical samples with the TP PCR method used in our laboratory.
Methods. Swabs from mucocutaneous lesions of patients with early syphilis and with genital non-syphilitic ulcers, frozen and fixed tissue samples of syphilitic mucocutaneous lesions, and cerebrospinal fluid (CSF) specimens were examined. The modalities of DNA extraction from the different clinical specimens and the performance conditions of the PCR are reported.
Results. TP DNA was demonstrated in almost all exudates, all frozen tissue samples of mucocutaneous syphilitic lesions, and some CSF samples. On the contrary, the samples of fixed syphilitic tissue and the swabs from genital non-syphilitic ulcers yielded negative results.
Conclusion. On the basis of these results, the authors propose that the TP PCR method, despite its cost, can be very useful to confirm a suspected chancre if dark-field microscopy cannot be performed and the serology is still negative or difficult to interpret as in the case of reinfection. In addition, the test seems useful to confirm the histopathologic diagnosis of early syphilis, provided a small portion of frozen tissue is available. On the contrary, the CSF reactivities found in this study cannot be evaluated because of the absence of clinical correlates.

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