For Early Syphilis, Are Three Doses of Benzathine Penicillin Better Than One?

While most people with diagnoses of early syphilis (primary, secondary, and early latent) respond to a single dose of benzathine penicillin (2.4 million units), about one quarter do not reach the fourfold decline in nontreponemal test titer considered a measure of successful treatment. Do three intramuscular injections work better than one? Investigators randomized 249 participants (mostly men, including 153 with HIV infection) to receive one or three weekly 2.4-million-unit doses of benzathine penicillin.

At 6 months, serologic responses to therapy were seen in 76% of the 1-dose group and 70% of the 3-dose group; responses to 3 doses were similar among participants with or without HIV (71% and 70%, respectively). Injection-site pain was mor…