Sexually Transmitted Infections on the Rise in PrEP Users.

Pre-exposure prophylaxis (PrEP) with oral Truvada (tenofovir plus emtricitabine) is effective at preventing HIV infection in high-risk homosexual men. In the United States, PrEP was approved in 2012 and is reimbursed by Medicaid and the majority of private insurers. The situation is diverse and not uniform in the European Union, being PrEP more widely used in France than in the rest of countries. Concerns have been raised that PrEP use may be accompanied by the phenomena of risk compensation or behavioral disinhibition, whereby PrEP users' perception of decreased risk of HIV acquisition may lead them to engage in overall riskier sexual practices and increase their chances of acquiring sexually transmitted infections (STIs) (Blumenthal, et al. Virtual Mentor. 2014;16:909-15). Modifiable factors that may influence the acquisition of STI include condom use, number of partners, partner characteristics, and healthcare-seeking behaviors. In addition, MSM may alter HIV risk mitigation practices while on PrEP by decreasing seroadaptive practices such as serosorting that is seeking a partner of similar perceived serostatus (Khosopour, et al. AIDS Behav. 2017;21:2935-44). High rates of STI have been reported among PrEP users, as well as high rates of condomless sex, and increasing rates of STI over time (Liu, et al. JAMA Intern Med. 2016;176:75-84; Kojima, et al. AIDS, 2016;30:2251-2). In a new study conducted in Montreal, Canada, increases in the rates of STI in PrEP users were demonstrated measuring incidence rates of STI before and following the initiation of PrEP in the same cohort. The authors measured the incidence of gonorrhea, chlamydia, and/or syphilis in 109 HIV-seronegative homosexual men 12 months before and 12 months after beginning Truvada for HIV prevention (Nguyen, et al. AIDS. 2018;32:523-30). New episodes of gonorrhea, chlamydia, and/or syphilis rose in the cohort after providing Truvada, as shown in Figure 1. Moreover, the incidence of three or more STI increased from 3.7 to 9.2 cases per 100 personyears in this cohort. The Canadian study highlighted that the rate of STI with PrEP was also higher than in a group of 86 homosexual men that had undergone PEP in Montreal during 2010-2015. Other findings of the study we the high rate of STI with anorectal location, symptomless STI (e.g., chlamydia) and the frequency of sex partners contacted by internet. The increased rates of STI in PrEP users suggest a need to reinforce counseling and STI diagnosis and treatment efforts. Although PrEP may provide a public health benefit beyond the immediate prevention of HIV infection as result of bringing into care high-risk homosexual men who might not otherwise be seeking care for STI, doctors in charge must take this opportunity for informing adequately on STI and the risks inherent to multiple and occasional sexual contacts.