Incidence of STIs Reduced With Doxycycline Postexposure Prophylaxis

THURSDAY, April 6, 2023 (HealthDay News) — Doxycycline postexposure prophylaxis is associated with a lower incidence of gonorrhea, chlamydia, and syphilis, according to a study published in the April 6 issue of the New England Journal of Medicine.

Anne F. Luetkemeyer, M.D., from the Zuckerberg San Francisco General Hospital and Trauma Center, and colleagues conducted a randomized trial involving men who have sex with men (MSM) and transgender women taking HIV preexposure prophylaxis (PrEP cohort) or persons living with HIV infection (PLWH cohort) and who had gonorrhea, chlamydia, or syphilis in the past year. Five hundred one participants (327 in the PrEP cohort and 174 in the PLWH cohort) were randomly assigned to 200 mg doxycycline within 72 hours after condomless sex or standard care without doxycycline. Sexually transmitted infection (STI) testing was performed quarterly.

The researchers found that an STI was diagnosed in 10.7 and 31.9 percent of quarterly visits in the doxycycline group and the standard-care group, respectively, in the PrEP cohort (relative risk, 0.34). An STI was diagnosed in 11.8 and 30.5 percent of quarterly visits in the doxycycline and standard-care groups, respectively, in the PLWH cohort (relative risk, 0.38). The incidences of the three STIs evaluated were lower with doxycycline, with relative risks of 0.45, 0.12, and 0.13 for gonorrhea, chlamydia, and syphilis, respectively, in the PrEP cohort; the corresponding values were 0.43, 0.26, and 0.23 in the PLWH cohort.

“The combined incidence of gonorrhea, chlamydia, and syphilis was lower by two-thirds with doxycycline postexposure prophylaxis than with standard care, a finding that supports its use among MSM with recent bacterial STIs,” the authors write.