PRIMARY SYPHILIS

By Gary M. White, MD

Primary syphilis Courtesy Michael O. Murphy, MD


Syphilis is a sexually transmitted disease cause by Treponema pallidum. See also congenital, secondary, tertiary and endemic. It usually presents as a genital ulcer. The name comes from an epic poem, describing Syphilus, the supposed first sufferer of the disease.

Clinical

In primary syphilis, solitary or multiple, painless ulcers or erosions called chancres occur. They tend to remain superficial but may become quite indurated. In women, the chancres may occur in the vagina or on the cervix and go unnoticed. Chancres may occur at other sites of inoculation (e.g. the anus in a homosexual man, the mouth after oral sex).

Syphilitic balanitis of Follmann is a rare manifestation of primary syphilis in which the glans and foreskin are bright red with multiple oozing superficial erosions. Often, there are swollen inguinal lymph nodes.

Differential Diagnosis

See penile ulcer.

Diagnosis

Traditionally, a non-treponemal test (e.g., RPR or VDRL) is done initially and if positive, a treponemal test (e.g, enzyme immunoassay) is performed. However, the nontreponemal test generally becomes positive 5-6 weeks after infection, shortly before the chancre heals. The treponemal enzyme immunoassay test--IgM antibody against T. palladium--is more sensitive for detecting primary syphilis as it becomes detectable about 2-3 weeks after infection, about the time the chancre appears. A positive treponemal test should be confirmed with a subsequent nontreponemal test.

In the case of positivity, the patient should be screened for ocular symptoms and a full neurologic exam performed to rule out ocular syphilis and neurosyphilis--among other things.

Treatment

Treatment should follow the current Public Health Service recommendations. In the past for primary, secondary or early latent disease, one dose of benzathine PCN IM 2.4 million units has been sufficient as long as neither neurosyphilis nor ocular syphilis are present. In the case of PCN allergy, minocycline 100 mg BID x 28 days, TCN 500 mg QID for 15 days or doxycycline 100 mg PO BID for 2 weeks have been used. In one large study, minocycline 100 mg BID x 28 days worked the best, i.e., better than PCN [Medicine 2016;95;e5773]. The RPR or VDRL titer should be followed to assure adequate treatment (look for at least a four-fold drop).

References

CMAJ November 22, 2011 vol. 183 no. 17 2015

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