Syphilis is a sexually transmitted infection caused by the spirochetaf organism Treponema pallidum. It is transmitted by sexual intercourse or transplacentally. HIV patients may contract syphilis concomitantly with their HIV infection. Since the introduction of penicillin and other antibiotics, it has become a much less serious disease than it used to be. Long-term complications are now very rare. The last cases of long-term complications that were seen in Brisbane, Australia, were in the early 1960s, in elderly patients who had acquired their primary infection many years before the introduction of penicillin. Syphilis occurs in all countries. Primary infections are still common.
Clinical presentation of syphilis
The first presentation of syphilis is a painless ulcer on the penis or on the vulva. This lesion is called a chancre (illustrated in Figs a, b, c).
Examples of primary chancres on the penis.
The process of laboratory diagnosis is as follows.
1. Dark ground examination of a smear from the lesion looking for motile spirochetes.
3. Fluorescent antibody test.
Primary chancre at the introitus of the vagina.
A 22-year-old female presented with a generalized rash which she thought was due to an allergy. The rash involved the whole body, and the palms of both hands and the soles of both feet (shown in Fig. below).
Young woman with a generalized syphilitic rash. The rash involved the whole body, and the palms of both hands and the soles of both feet.
She also had a chancre on the perineum (see Fig. below).
Chancre and a few small condylomata on the vulva near the perinum.
Testing showed a few motile spirochetes in a smear from her perineal lesion (see Fig below) and serologic tests for syphilis were positive. She was given a course of penicillin and her symptoms subsided.
A spirochete can be seen with the dark ground illumination of a wet preparation from a smear from the surface of a chancre. In real time the organism was motile.
Note: Had this patient presented in 2006 and later, she would not have had the serologic tests that were introduced in the 1940s but a fluorescent antibody test instead (see Fig. below).
Positive fluorescent antibody test. A culture of spirochetes is used for the test. The serum to be tested is added to the cultur; a green marker dye is added, and a smear of the mixture is examined using a fluorescent microscope.