STI Prophylaxis in High-Risk Populations

Current Evidence-Based Prophylaxis Strategy

The CDC recommends doxycycline post-exposure prophylaxis (doxy PEP) at 200 mg within 72 hours after sexual contact as the sole recommended antibiotic prophylaxis for preventing bacterial STIs in gay, bisexual, and other men who have sex with men (MSM) and transgender women with a history of bacterial STI in the past 12 months, with a strength of evidence supporting a reduction in syphilis and chlamydia infections by >70% and gonococcal infections by approximately 50% 1
Doxy PEP should be offered to MSM and transgender women who have had at least one bacterial STI (syphilis, chlamydia, or gonorrhea) diagnosed in the past 12 months, using shared decision-making for those without recent STI diagnosis but engaging in high-risk sexual activities 1

The CDC guidelines establish doxy PEP as the recommended prophylaxis for MSM and transgender women, with the goal of reducing the incidence of bacterial STIs in this high-risk population 1

For MSM and transgender women presenting for STI prevention counseling, the CDC recommends assessing eligibility criteria, including history of bacterial STI in the past 12 months, and strongly recommending doxy PEP if eligible, with a dosing regimen of 200 mg within 72 hours after oral, vaginal, or anal sexual contact 1

The Centers for Disease Control and Prevention (CDC) recommends doxy PEP (200 mg taken within 72 hours after sexual contact) only for preventing syphilis, chlamydia, and gonorrhea in specific high-risk populations 2, 3
The 2024 CDC guidelines specifically state that doxy PEP reduces syphilis and chlamydia infections by >70% and gonococcal infections by approximately 50% 3
The CDC guidelines do not mention the use of doxy PEP for preventing M. genitalium infections 2, 3, 4

Patients should be counseled that while doxy PEP may help prevent syphilis, chlamydia, and gonorrhea, it is unlikely to prevent M. genitalium infections 2
Regular STI screening remains essential, especially for high-risk populations, as doxy PEP does not provide comprehensive protection against all STIs 4

Follow CDC guidelines for appropriate use of doxy PEP in eligible populations for preventing syphilis, chlamydia, and gonorrhea only 3, 4
Maintain comprehensive STI prevention strategies including regular screening, as doxy PEP does not protect against M. genitalium 2, 5