Sexually transmitted infections (STIs) continue to have a significant impact on the lives of adolescents and young adults. According to the Centers for Disease Control and Prevention’s (CDC) 2021 surveillance report, rates of gonorrhea and syphilis in the United States were at their highest since the early 1990s. Chlamydia, one of the most common STIs, had a peak rate in 2019, but more recent rates may have been impacted by the COVID-19 pandemic. In 2021, those 15-24 years of age accounted for 58.5% of all chlamydia infections, 40.4% of all gonorrhea infections, and 18.3% of all syphilis infections in the US.
While pediatricians should discuss sexual health and STI screening with all their adolescent and young adult patients, LGBTQ+ youth are disproportionately impacted by STIs. For example, cisgender men who have sex with men have significantly higher rates of HIV, gonorrhea, and syphilis. These disparities are likely related to unequal access to care, systemic homophobia/transphobia, stigma, and differences in sexual networks and are even more pronounced for those with intersectional minoritized identities such as LGBTQ+ youth of color.1
Courtesy Dr. Warus
Dr. Jonathan Warus
In the past 12 years, there have been significant advances in HIV prevention methods, including the approval and use of pre-exposure prophylaxis or “PrEP” (a medication regimen that is taken on an ongoing basis to provide highly effective protection against HIV infection) and more widespread use of post-exposure prophylaxis or “PEP” (a medication regimen taken for 1 month after a potential exposure to HIV to prevent HIV from establishing an ongoing infection) outside of the medical setting. While these interventions have the potential to decrease rates of HIV infection, they do not prevent any other STIs.2-3
The current strategies to prevent bacterial STIs include discussions of sexual practices, counseling on risk reduction strategies such as decreased number of partners and condom use, routine screening in those at risk every 3-12 months, and timely diagnosis and treatment of infections in patients and their partners to avoid further transmission.4 Given the increasing rates of bacterial STIs (gonorrhea, chlamydia, and syphilis), additional biomedical prevention methods are greatly needed.
Doxycycline as post-exposure prophylaxis
Doxycycline is a tetracycline antibiotic effective against a wide range of bacteria and is commonly used in the treatment of acne, skin infections, Lyme disease, and STIs, and can also be used in the treatment and prevention of malaria.5 For STIs, doxycycline is currently the recommended treatment for chlamydia and is also an alternate therapy for syphilis in nonpregnant patients when penicillin is not accessible or in those with severe penicillin allergy.4 This medication is often well tolerated with the most common side effects including gastrointestinal irritation and photosensitivity. Doxycycline is contraindicated in pregnancy due to its potential impact on tooth and bone development.5
Given its general tolerability and activity against bacterial STIs, new and emerging studies have examined doxycycline as post-exposure prophylaxis (DoxyPEP: one dose of doxycycline 200 mg PO within 72 hours after unprotected sex) in an attempt to decrease the incidence of new bacterial STIs in populations at risk. Three of the studies cited in the preliminary CDC DoxyPEP guidelines were conducted in cisgender men who have sex with men and transgender women either living with HIV or taking PrEP for HIV prevention. All three studies demonstrated significantly lower risk of chlamydia and syphilis, while two of the studies also showed a significantly lower risk of gonorrhea. One additional study was conducted in cisgender women in Kenya. This study did not show any statistically significant difference in the risk of chlamydia or gonorrhea in the intervention group, but may have been limited by low adherence to the DoxyPEP regimen. There were no serious adverse events reported in any of the studies attributed to doxycycline.6