title: High-dose oral amoxicillin plus probenecid is highly effective for syphilis in patients with HIV infection.
abstract: 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 amoxicillin 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 hemagglutination test. Patients with neurosyphilis diagnosed by cerebrospinal fluid examination were excluded. Successful treatment 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 patients), and efficacy for primary, secondary, early latent, late latent, and unknown duration syphilis was 93.8% (95% CI, 68.1%-99.8%; 15/16), 97.3% (95% CI, 92.9%-99.2%; 142/146), 100% (95% CI, 90.5%-100%; 37/37), 85.7% (95% CI, 58.6%-96.4%; 18/21), and 92.4% (95% CI, 81.9%-97.3%; 61/66), respectively. Treatment duration was mostly 14-16 days (49.7%) or 28-30 days (34.3%), with efficacy of 94.4% (134/142) and 95.9% (94/98), respectively; 96.3% of successfully treated patients achieved a ≥4-fold decrement in RPR titer within 12 months. Adverse events were noted in 28 (9.8%) patients, and 25 of these (89.3%) were successfully treated. Only 6% of patients underwent lumbar puncture.
  
  
  CONCLUSIONS
  The combination of oral amoxicillin 3 g plus probenecid was highly effective and tolerable for the treatment of syphilis in patients with HIV-1 infection.
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Tanizaki
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo Center for AIDS Research, Kumamoto University, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishijima
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Aoki
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo.
authors.forename: Katsuji
authors.initials: K
authors.lastname: Teruya
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kikuchi
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo Center for AIDS Research, Kumamoto University, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Oka
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, Tokyo Center for AIDS Research, Kumamoto University, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Gatanaga
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000658:Amoxicillin / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D018791:CD4 Lymphocyte Count; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008297:Male; D011339:Probenecid / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D012189:Retrospective Studies; D012307:Risk Factors; D013587:Syphilis / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology / Q000517:prevention & control; D013588:Syphilis Serodiagnosis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D000658:Amoxicillin; D011339:Probenecid
keywords: HIV; MSM; amoxicillin; syphilis; treatment