Bacterial sexually transmitted infections and related antibiotic use among individuals eligible for doxycycline post-exposure prophylaxis in the United States

BackgroundDoxycycline postexposure prophylaxis (doxyPEP) can prevent bacterial sexually transmitted infections (STIs) among men who have sex with men (MSM) and transgender women. However, concern surrounds the volume of tetracycline use needed to realize these benefits, and whether potential risks of increased tetracycline exposure outweigh benefits of doxyPEP for specific populations. MethodsWe estimated incidence rates of gonorrhea, chlamydia, and syphilis and related antibiotic prescribing among commercially-insured US males and transgender individuals using the Merative MarketScan(R) Research Databases during 2016-2019. We evaluated potential impacts of doxyPEP implementation under risk-based prioritization schemes focusing on HIV pre-exposure prophylaxis (PrEP) recipients, people living with HIV (PLWH), and people with prior STI diagnoses. ResultsIncidence rates of gonorrhea, chlamydia, and syphilis among PLWH and PrEP recipients with [≥]1 STI diagnosis in the prior year totaled 33.3-35.5 episodes per 100 person-years. Direct effects of doxyPEP could prevent 7.4-9.6 gonorrhea diagnoses, 7.3-8.1 chlamydia diagnoses, and 3.1-5.9 syphilis diagnoses per 100 person-years within these populations. Expected increases in tetracycline consumption resulting from doxyPEP implementation were equivalent to 271.9-312.9 additional 7-day doxycycline treatment courses (resembling current standards for chlamydia treatment) per 100 person-years of use. This increase corresponded to the equivalent of 36.5-37.0, 37.0-38.7, and 46.1-100.2 additional 7-day doxycycline treatment courses for each prevented chlamydia, gonorrhea, and syphilis episode, respectively. These increases in doxycycline use exceeded anticipated reductions in STI-related prescribing of cephalosporins, macrolides, and penicillins by 16-69 fold margins. ConclusionsEstimates of changes in antibiotic use and STI incidence resulting from doxyPEP implementation in differing populations may inform priority-setting for this intervention.