Effects of HIV infection on the serologic manifestations and response to treatment of syphilis in intravenous drug users

Objective: To describe the effects of human immunodeficiency virus (HIV) infection on the serologic manifestations and response to treatment of syphilis in intravenous drug users. Design: Cohort study of intravenous drug users. Setting: Medical clinic in a hospital-based methadone maintenance treatment program in New York City. Patients: Fifty patients with syphilis, of whom 31 were HIV seropositive and 19 HIV seronegative. Measurements: Serologic tests for syphilis and clinical manifestations. Results: Stage of syphilis at presentation was not associated with HIV serologic status. No unusual or fulminant manifestations of early syphilis or neurosyphilis were noted among HIV-seropositive cases. Maximum nontreponemal titers were higher among HIV-seropositive (median, 1:128) than among HIV-seronegative (median, 1:32) patients with syphilis (P = 0.05); this difference was present only among patients with first-episode syphilis. All 26 evaluable, HIV-seropositive patients treated for syphilis responded appropriately, including 13 patients given standard or less-than-standard doses of penicillin. Seven of 43 patients (16%) showed reversion to negative treponemal antibody assay results after treatment for syphilis; this finding was not associated with HIV infection, CD4 count, or stage of syphilis. Low nontreponemal titer was weakly associated with treponemal test reversion. Conclusions: Infection with HIV did not alter the stage at presentation, clinical course, serologic manifestations, or response to treatment of syphilis in this cohort of intravenous drug users.