Single-Dose Azithromycin Comparable to Benzathine Penicillin G for Syphilis in Patients with HIV

SAN FRANCISCO, CA—In an area of low prevalence of macrolide-resistant Treponema pallidum, single-dose azithromycin had comparable efficacy to benzathine penicillin G in the treatment of early syphilis among patients who were HIV-positive, a prospective study concluded at IDWeek 2013.

“HIV-infected patients are rarely evaluated in the era of combination antiretroviral therapy (cART),” Chien-Ching Hung, MD, MIH, PhD, of National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan noted.

Adding that alternatives to benzathine penicillin G in patients with early syphilis who are allergic to or intolerant are limited, Dr. Hung and his colleagues evaluated the effectiveness and tolerability of a single 2g dose of azithromycin in treatment of early syphilis in patients with HIV infection.

Researchers prospectively observed 205 consecutive patients (204 men who have sex with men) with early syphilis who received either 1 dose of benzathine penicillin G or a single 2g dose of azithromycin under direct observation between May 2012 and September 2013. Thirty seven patients (18%) had primary, 62 (30.2%) secondary, 7 (3.4%) both primary/secondary, and 108 (52.7%) early latent syphilis.

T. pallidum was detected from clinical specimens using PCR assays; genotypic resistance to macrolides was determined. Information on adverse effects was solicited 24 and 48 hours following treatment. Tests for rapid plasma regain (RPR) titer were performed at baseline and every 3 months post-treatment. The primary end point was decline of rapid plasma reagin titer by ≥4-fold at 6 months post-treatment.

 “One (1.4%) of the 69 T. pallidum strains identified harbored macrolide resistance mutations (A2058G),” Dr. Hung noted.

The mean CD4 count was 528 cells/μl (range, 34–1455) and plasma HIV RNA load was 1.3 log10 copies/ml (1.3–6.0 log10). After taking azithromycin, 79.7% of the 161 patients evaluable for safety developed any gastrointestinal AE; 33.8%, central nervous system AEs; and 14.2%, Jarisch-Herxheimer reaction. Investigators concluded that no significant association was observed between effectiveness by 3 months or adverse events and use of cART.

Dr. Hung reported, “after 6 months of treatment, 68% of HIV-infected patients receiving azithromycin for early syphilis achieved a 4-fold or greater decline of RPR at 6 months of treatment.”