Grant: Project Grant

Globally, syphilis, chlamydia and gonorrhea are three of the most common sexually transmitted infections (STI). Over the last decade, these STIs have seen a resurgence in many parts of the world, including Canada, with the bulk of infections seen in major urban centres. More recently, these increases have been even more significant, with a 150% increase in these infections in Canada between 2014-2018. These infections have primarily affected gay, bisexual, and other men who have sex with men (gbMSM). Further, HIV-positive gbMSM are disproportionately affected by many STIs. In addition to playing a role in the enhanced transmission of HIV, STIs also place individuals living with HIV at higher risk of complications and more severe disease. A few years ago, a small pilot study found that doxycycline - an inexpensive, well-tolerated antibiotic - given daily may prevent new STIs in HIV-positive gbMSM. More recently, another study looked at the use of one dose of doxycycline given after a sexual encounter for prevention of STIs, and the results of this study demonstrated protection against STIs as well. Based on these promising data, along with the concerning increases in these STIs, the current study will examine the use of doxycycline as either a daily preventative therapy (preexposure prophylaxis, or PrEP) or an 'after sex' prevention tool (postexposure prophylaxis, or PEP) for STIs in gbMSM living with HIV. While examining for efficacy as its primary goal, this study will also do a thorough examination of some of the potential challenges and concerns associated with the use of a daily antibiotic: drug resistance, tolerability and side effects, and how acceptable this drug is for people to take regularly.