Recently, the U.S. Centers for Disease Control and Prevention (CDC) released clinical guidelines on the use of doxycycline postexposure prophylaxis (doxy PEP) for bacterial sexually transmitted infection prevention, calling doxy PEP "a novel, ongoing, patient-managed biomedical STI prevention strategy for a selected population". However, not much is known about the existing use of antibiotics as STI prevention in the U.S. populations that have the potential to benefit from it.

A new study led by research fellow Michael Traeger, with senior author Julia Marcus, Douglas Krakower, and collaborators Kenneth Mayer and Samuel Jenness aimed to learn more about awareness of and interest in bacterial STI prevention. The study, online now in the journal Sexually Transmitted Diseases, highlights the need for prompt guidance on effective doxyPEP dosing and timely efforts to monitor real-world use. Drs. Traeger and Marcus discuss the study in this Q&A.
 

Q: First, some background about bacterial sexually transmitted infection (STI) prophylaxis. The CDC has called doxy PEP “the first new STI prevention tool in decades, at a time when innovation in the nation’s fight against STIs is desperately needed.” What has taken so long to find a new way to protect against STIs? Why are these new guidelines important?

Dr. Marcus: Interventions to prevent STIs have a long history, going back to the military’s use of silver and mercury for U.S. troops in World War I. The military later used antibiotics for STI prevention, but when gonorrhea started to develop resistance, interest waned. As STI rates have increased steeply over the past couple decades, particularly for syphilis, there has been renewed interest in antibiotics as a prevention strategy, leading to recent clinical trials on doxy PEP and now the new doxy PEP guidelines.  

Q: Why did you conduct this study?

Dr. Marcus: Several studies had explored the use of antibiotics for STI prevention among gay and bisexual men in Europe and Australia, but few studies had been conducted in populations likely to benefit in the U.S. We thought it was important to get a sense of what things looked like at baseline, before CDC issued their final recommendations on doxy PEP and it was more widely implemented. We wanted to understand whether people had heard of this strategy, their level of interest, and if and how they’d used it before.

Q: Tell us about what you expected to find through the survey.

Dr. Traeger: Before the study, we knew there had been increasing efforts from community to spread the word about doxy PEP and how community members can use it to protect themselves from STIs. As with previous developments in HIV and STI prevention, like HIV pre-exposure prophylaxis (PrEP), we expected that some gay and bisexual men in the US were likely already using doxy PEP and sharing information on how to use doxyPEP through their networks.

Q: What did survey findings show? Was your team surprised by these findings?

Dr. Traeger:  We surveyed over 900 people who use online social networking apps that are primarily used by gay and bisexual men. We found that about half of respondents had ever heard of using antibiotics for STI prevention, and after learning about it, nearly all expressed interest in using it. While about one in five respondents had ever used antibiotics for STI prevention, many had used certain types of antibiotics, or certain dosing strategies, that have not been recommended by the CDC for STI prevention. We found that respondents reported a range of different reasons for wanting to use doxy PEP, and also a variety of concerns related to using antibiotics frequently.

Q: Your study provides the first national estimate of the prevalence of STI prophylaxis use in the U.S. What are the potential implications of this study for public health? What future studies are you and your team considering to expand on this work?

Dr. Traeger: Our study provides a starting point for monitoring uptake of doxy PEP as an STI prevention strategy in the US, as we expect uptake to increase following the recent release of the CDC guidelines which recommend its use for some populations. The near-universal interest in doxy PEP was higher than in previous studies on doxy PEP in other settings, and suggests that doxy PEP uptake may rapidly increase in the next few years. Our study highlights that effectively delivering doxy PEP to those who will benefit from its use will mean considering individuals’ preferences and needs, and ensuring potential users are supported and informed about how to use doxy PEP correctly. Next, we are planning to investigate how doxy PEP use outside of clinical trials may reduce bacterial STIs among gay and bisexual men in the US.