P568 Positivity of Syphilis, Rectal Gonorrhea and Rectal Chlamydia among MSM PrEP Users in Baltimore City, Maryland

Background Bacterial STIs such as syphilis, rectal gonorrhea (GC) and chlamydia (CT) are strongly associated with increased risk of HIV acquisition, and are a marker of ongoing sexual risk behavior among HIV pre-exposure prophylaxis (PrEP) users. STI positivity among men who have sex with men (MSM) PrEP-users in settings where PrEP has been implemented is understudied. Our objective was to determine syphilis and rectal GC/CT positivity among MSM PrEP-users enrolled in a large PrEP demonstration project in Baltimore City, Maryland. Methods The demonstration project was a collaboration between a city health department, an academic evaluation partner, six clinical sites and one CBO. STI results at PrEP initiation and routine 6- and 12-month PrEP-care visits were collected among MSM receiving PrEP at participating clinical sites between September 30, 2015-March 31, 2018. Syphilis and rectal GC/CT positivity was calculated among those screened at each visit. Results During the study period, 290 MSM initiated PrEP, of whom 46.9%(136) were Black/African-American, and 51.4%(149) aged 25–34 years. At PrEP initiation, 79.2%(230) and 56.1%(165) were screened for syphilis and rectal GC/CT, respectively; the proportion screened at 6- and 12-month PrEP-care visits was slightly lower. Overall, including PrEP initiation and care visits, 11.6%(30/258) were ever syphilis positive, 17.9%(35/196) ever rectal GC positive, and 22.5%(44/196) ever rectal CT positive. Specifically, at PrEP initiation, 7.8%(18/230) were syphilis positive; 11.1%(18/162) rectal GC positive, and 11.7% (19/162) rectal CT positive. Positivity at 6- and 12-month PrEP-care visits was similar to positivity at PrEP initiation. Conclusion Despite CDC recommendations for biannual STI screening among PrEP-users, the proportion of MSM PrEP-users screened was suboptimal. The overall and ongoing positivity of syphilis and rectal GC/CT suggest that a substantial proportion of MSM PrEP-users may be engaging in ongoing sexual risk behaviors. Strategies are needed to encourage providers to screen PrEP-users more frequently for STIs and promote safer sexual practices. Disclosure No significant relationships.