Serologic response to treatment of syphilis in patients with HIV infection.

BACKGROUND: Much controversy exists concerning the manifestations, therapy, and response to treatment of syphilis in patients coinfected with the human immunodeficiency virus (HIV).

OBJECTIVE: To assess the effect of HIV infection on the serologic response to treatment of patients with syphilis.

METHODS: Sixty-four HIV-seropositive patients with syphilis were matched with 64 patients with syphilis who were HIV negative. Matching criteria included age (+/- 5 years), sex, race, initial rapid plasma reagin (RPR) titer (+/- 1 dilution), and stage of syphilis at entry. There were 26 matched patients with early syphilis, 26 matched patients with late syphilis, and 12 matched patients with biological false-positive RPR. The HIV-positive patients with early syphilis received three doses of penicillin G benzathine. All other patients received treatment as recommended by the Centers for Disease Control and Prevention, Atlanta, Ga. Our study's major end points were clinical and serologic response to treatment.

RESULTS: All 16 patients with symptomatic syphilis were cured. No patient developed clinical signs of neurosyphilis during the 12-month follow-up period. Twenty-nine (56%) of 52 HIV-positive patients with early or late syphilis did not have a fourfold decrease in RPR titer 6 months after treatment compared with 20 (38%) of 52 matched controls (P = .06). No unique characteristics identifying patients who did not respond serologically could be established. The HIV-positive patients with initial RPR less than 1:32 experienced a significantly slower decrease in RPR at 12 months than did the controls (P < .001).

CONCLUSIONS: Patients with syphilis who are HIV positive are less likely to experience serologic improvement after recommended therapy than are patients with syphilis who are HIV negative. Patients with HIV infection who contract syphilis should receive intensive and prolonged follow-up, and consideration should be given to designing alternative regimens.