Single Dose of Antibiotic Cured Early Syphilis, Even in Those With HIV

BOSTON — One dose of benzathine penicillin G for the treatment of early syphilis was shown to be noninferior to a regimen of three weekly doses a week apart, even among people who are living with HIV, a randomized trial showed.

At 6 months among patients with and without HIV, the cumulative response was 76% with one dose of benzathine penicillin G compared with 70% with three doses, fulfilling the prespecified 10% margin of noninferiority for the one-dose therapy, reported Jodie Dionne, MD, MSPH, of the University of Alabama at Birmingham, during the IDWeek annual meeting.

The difference in the proportion of those with serological responses between the two groups was -0.05 (95% CI -0.17 to 0.07).

Among the patients living with HIV, 76% responded to one dose at 6 months compared with 70% with three doses. The difference in the proportion of those with serological responses between the groups was -0.06 (95% CI -0.22 to 0.09).

Syphilis has been steadily increasing over the past decades, initially in men who have sex with men, and more recently with congenital infections, and among persons with opposite sex partners, Dionne said, noting that there have also been high rates of co-infection among those living with HIV.

“Some clinicians are nervous that when dealing with people who have compromised immune systems, such as those living with HIV, that one dose may not be enough to adequately protect these patients,” Dionne told MedPage Today. “Our findings indicate that one dose is sufficient to create a response suggestive of cure using the rapid plasma reagin (RPR) test that looks for syphilis-specific antibodies.”

Another benefit of the one-dose therapy, she noted, is that it may take pressure off the chronic shortages of supplies of benzathine penicillin G.

Session co-moderator Satoshi Kamidani, MD, of Emory University School of Medicine in Atlanta, told MedPage Today that “there really is no difference between one dose and three doses” for early syphilis, but noted that for late syphilis, clinicians prefer the three-dose regimen.

Kamidani also said that physicians with patients who have both syphilis and HIV would tend to want to treat patients more heavily, and “this is why they did this study, and they demonstrated that either treatment works for this co-infected population, too.”

For this study, the researchers included 249 adults with untreated primary (33%), secondary (47%), or early latent (30%) syphilis. Most patients were asymptomatic and were identified in routine screening at the clinic. Mean age was 35, 97% were men, 62% were Black, and 25% were white.

Of these patients, 61% were living with HIV, and 1% had unknown status.

They were randomized to receive one dose of benzathine penicillin G at baseline (n=124) or three doses at baseline and then at 7 days and at 14 days (n=125).

Local adverse events (pain or tenderness) were reported by 81% of patients after treatment. Three serious adverse events occurred — one in the one-dose group and two in the three-dose group — but all were resolved and deemed unrelated to treatment.

“We will be following these patients for a year, and we think that there will be more people who will achieve the milestone at that time,” Dionne said.

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