High-Dose Oral Amoxicillin Plus Probenecid Is Highly Effective for Syphilis in Patients With HIV Infection

Background. Intramuscular benzathine penicillin G (BPG) is widely used for the treatment of syphilis. However, BPG is not available in some countries. This study examined the effectiveness and safety of high-dose oral amoxi-cillin plus probenecid for the treatment of syphilis in patients with human immunodeficiency virus type 1 (HIV-1). Methods. This retrospective observational study included 286 HIV-infected male patients with syphilis (median age, 36 years; median CD4 count, 389 cells/µL) who were treated with oral amoxicillin 3 g plus probenecid. Syphilis was diagnosed by both serum rapid plasma reagin (RPR) titers ≥8 and positive Treponema pallidum hemagglutina-tion test. Patients with neurosyphilis diagnosed by cerebrospinal fluid examination were excluded. Successful treat-ment was defined as a at least 4-fold decrement in RPR titer. Results. The overall treatment efficacy was 95.5 % (95 % confidence interval [CI], 92.4%–97.7%; 273/286 pa-tients), and efficacy for primary, secondary, early latent, late latent, and unknown duration syphilis was 93.8