Syphilis test mucocutaneous ulcer


Dry swab for NAA detection.

Or if available (consult with a pathologist). Wet preparation from base of lesion (eg, chancre) after gentle cleansing with saline.

The slide must be examined immediately by darkfield microscopy.

If this is not available on site, alternatively smear sample on a glass microscope slide should be submitted for IFA or DFA testing.


NAA detection (preferred).

Darkfield microscopy; DFA or IFA on fixed smear.


Diagnosis of primary syphilis.


Positive on NAA -A positive result is suggestive of current infection with Treponema pallidum. A negative result does not exclude the diagnosis.


Treponema pallidum is identified by characteristic morphology and motility on darkfield microscopy.

Because it is difficult to distinguish T. pallidum from other spirochaetes which are part of the normal flora of the gastrointestinal tract, darkfield microscopy is unsuitable for the examination of specimens from oral or anal lesions.

A positive result (darkfield microscopy, IFA or DFA) confirms a clinical diagnosis of primary syphilis.


Kellog DS. Health Lab Sci 1970; 7: 34-41.

Garner MF and Robson JH. J Clin Micro 1968; 21: 576-577.

Go Back

Page last updated:

Copyright © 2021 RCPA. All rights reserved.