Syphilis and neurosyphilis in a human immunodeficiency virus type-1 seropositive population: evidence for frequent serologic relapse after therapy.

OBJECTIVE: To describe clinical and treatment aspects of syphilis infection among patients seropositive for the human immunodeficiency virus (HIV). PATIENTS AND METHODS: Results of serologic tests for syphilis, CD4+ T-lymphocyte counts, and clinical response to therapy were retrospectively monitored in 100 HIV-infected adults with syphilis from a tertiary-care military HIV program.
RESULTS: Of the 1,206 HIV-infected patients, 100 (8.3%) in the cohort had syphilis; 61 patients were treated for active syphilis. Serologic or clinical relapse eventually occurred in 10 of the 56 treated patients (17.9%) with follow-up available; 7 of the 10 who relapsed had previously received high-dose intravenous or procaine penicillin therapy. Relapse occurred more than 12 months after initial therapy in 6 of 10 patients (60%) who experienced relapse; 5 patients experienced multiple relapses. The mean CD4+ T-lymphocyte count was not predictive of relapse. Patients with reactive cerebrospinal fluid (CSF) Venereal Disease Research Laboratory (VDRL) test titers (4 of 7 patients [57%]) or the rash of secondary syphilis (4 of 14 patients [29%]) were at highest risk of subsequent relapse or treatment failure when monitored for an average of 2 years.
CONCLUSION: Standard penicillin regimens, including high-dose intravenous penicillin, transiently lowered serum VDRL titers in nearly all cases, but were sometimes inadequate in preventing serologic and clinical relapse in patients infected with HIV type-1, especially among those with secondary syphilis and reactive CSF VDRL titers. Careful long-term follow-up is essential, and repeated courses of therapy may be needed for patients infected with HIV type-1 who have syphilis.