PROJECT ABSTRACT Men who have sex with men (MSM) are at higher risk for HIV and sexually transmitted infections (STIs) that increase HIV risk, such as Neisseria gonorrhoeae and Chlamydia trachomatis. HIV pre-exposure prophylaxis (PrEP) users—many of whom are MSM—are also at increased risk for STIs. U.S. guidelines recommend that PrEP users undergo frequent screening in multiple anatomic sites (pharyngeal, urogenital, and rectal) for asymptomatic infections. However, lower- and middle-income countries (LMICs) lack such guidelines, resulting in missed opportunities for STI screening and treatment among LMIC PrEP users. Antimicrobial resistance (AMR) in N. gonorrhoeae is an urgent global health threat and the prevalence is highest in LMICs, where access to diagnostics is limited. In particular, the Western Pacific Region, which includes the LMIC of Vietnam, has seen increasing spread of AMR in N. gonorrhoeae, which has spread worldwide. Major gaps exist in understanding the drivers of AMR in N. gonorrhoeae in LMICs. In this study, investigators from UCLA and Hanoi Medical University will investigate the acceptability and feasibility of C. trachomatis and N. gonorrhoeae screening among MSM and transwomen engaged in an HIV PrEP program in Hanoi, Vietnam. We hypothesize that screening will be acceptable and feasible. We will also investigate risk factors for AMR and genomic relationships between commensal Neisseria and N. gonorrhoeae at genetic loci associated with AMR, hypothesizing that recent antibiotic use is a risk factor for AMR. AIM 1: (a) To determine the distribution of anorectal, pharyngeal, and urogenital C. trachomatis and N. gonorrhoeae infections among MSM and transgender women PrEP users (n=1,300) in Hanoi, Vietnam and (b) To evaluate the acceptability and feasibility, including willingness to pay, of rapid, triple-site testing. AIM 2: (a) To collect, culture, and perform antibiotic susceptibility testing on N. gonorrhoeae and oropharyngeal Neisseria species to investigate the prevalence and correlates of AMR and b) To perform whole-genome sequencing on pairs of N. gonorrhoeae and Neisseria species isolated from within the same individual to investigate relationships within genes associated with antimicrobial resistance in N. gonorrhoeae. This two-year project has four phases. Phase 1 will last three months and will involve development of study materials, planning, and training. Phase 2 will last one year and will evaluate acceptability and feasibility of C. trachomatis and N. gonorrhoeae screening. Phase 3 will last 9 months and will involve antimicrobial susceptibility testing and whole genome sequencing. Phase 4 will last 3 months and will involve dissemination of findings through manuscripts, presentations, and sharing of data with local government and health agencies. Findings from the study will form the foundation for a future R01-proposal to investigate the impact of routine screening and treatment of STIs on the development o...