Family Doctors Can Intervene to Treat and Prevent STIs

VANCOUVER, British Columbia — Family physicians should familiarize themselves with doxycycline post-exposure prophylaxis (doxy PEP) as a prescription for patients who frequently have unprotected sex (including oral, anal, and vaginal) with multiple partners, according to a presentation at the Family Medicine Forum (FMF) 2024. Doxy PEP decreases the risk for bacterial sexually transmitted infections (STIs).

Many family physicians may be unaware of doxy PEP as a means of avoiding STIs. “Doxy PEP is an incredible tool that can be used within 72 hours of unprotected sex to reduce bacterial STI risk,” said James Owen, MD, assistant professor of family and community medicine at the University of Toronto, Toronto, Ontario, Canada.

The US Centers for Disease Control and Prevention point to data from three randomized, controlled trials that demonstrate the ability of doxy PEP to decrease syphilis and chlamydia infections by more than 70% and decrease gonococcal infections by about 50%, noted Jordan Goodridge, MD, assistant professor of family and community medicine at the University of Toronto.

Optimizing Doxy PEP

Doxy PEP (200 mg) is most effective when administered in the first 24 hours after unprotected sex, explained Goodridge. It is recommended that patients repeat the 200-mg dose if they are sexually active again within 24 hours.

To ensure optimal absorption of doxy PEP, the drug should not be taken with antacids or multivitamins, said Goodridge. Antacids “can bind to doxycycline and prevent it from being absorbed,” he said.

A key concern about doxy PEP is the development of antimicrobial resistance, noted Goodridge. “We don’t have long-term studies to give us an idea about what this risk is, to quantify it. The studies we have are relatively short, generally less than a year, and didn’t suggest that there was a huge risk [for antimicrobial resistance].”

Moreover, doxycycline is teratogenic, and its use is contraindicated in pregnancy, said Goodridge. If a pregnant patient is being treated for syphilis, then penicillin is the treatment of choice. For pregnant patients with penicillin allergy, Public Health Agency of Canada guidelines call for penicillin desensitization followed by penicillin.

The rate of syphilis has been rising in Canadian women of reproductive age, thus increasing the potential for congenital syphilis, noted Goodridge.

Benefits of HPV Vaccine

The 9-valent HPV vaccine is recommended in Canada for patients aged 9-26 years, but those aged 27 years or older at ongoing risk for HPV exposure may receive the 9-valent HPV vaccine after discussion with their healthcare providers, noted Owen.

High-risk patients can benefit from the vaccine even though they have likely had exposure to HPV, he added. “If someone has multiple sexual partners, they have probably been exposed to HPV at some point,” said Owen. “You still could reduce a patient’s risk for being exposed to certain oncogenic strains [of HPV]. Certainly, within our practices, we’re often giving it [that is, the HPV vaccine] to higher-risk individuals, including men having sex with men.”

HIV Prevention

“Condoms are still a mainstay of HIV and STI prevention, but condom use is going down,” said Owen.

In a national survey commissioned by the Toronto-based organization LetsStopAIDS and including more than 1100 Canadians aged 18-24 years, 24% of respondents said they use condoms “all the time.” In 2020, by contrast, more than half (53%) of respondents reported that they use condoms all the time.

Updated Canadian guidelines on the use of HIV pre-exposure prophylaxis (PrEP) are expected to be released in 2025 and will address questions about how frequently individuals taking HIV PrEP should be tested to ensure a negative HIV result. The guidelines will also provide guidance as to whether HIV serology or HIV viral load should be captured, said Owen. Patients in Canada who take HIV PrEP are now generally screened for HIV every 3 months.

A new HIV PrEP tool that has become available to Canadian clinicians is the injectable drug cabotegravir, which is dosed every 2 months.

Owen and Goodridge reported having no relevant financial relationships.