Azithromycin versus Penicillin G Benzathine for Early Syphilis

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Abstract
The demonstration in Tanzania of equivalent efficacy of azithromycin and penicillin G benzathine for treating early syphilis and presumed early latent syphilis (rapid plasma reagin titer, ≥1:8) represents a potentially useful advance in syphilis control. In a randomized trial reported in this issue of the Journal, Riedner et al.1 achieved cure rates of 97.7 percent with 2 g of azithromycin given orally and 95.0 percent with 2.4 MU of penicillin G benzathine given intramuscularly. Positive or negative status with respect to human immunodeficiency virus (HIV) infection did not influence the results of treatment. Titers on rapid plasma reagin tests fell fastest in those with the highest initial titers, as shown previously by others.2 Inclusion of secondary syphilis and follow-up beyond nine months would have strengthened this study. An ongoing trial in Madagascar and four U.S. cities is comparing azithromycin and penicillin G benzathine for treatment of early syphilis. A Ugandan study3 followed patients with reactive serologic tests for syphilis at 10-month intervals after nonrandomized treatment with 2.4 MU of penicillin G benzathine, 1.0 g of azithromycin, or both; the three regimens yielded similar overall cure rates, although patients with initial antibody titers of 1:4 or greater (on the toluidine red unheated serum test) actually had better outcomes after azithromycin therapy than after penicillin G benzathine therapy alone.