effectiveness, doxycycline, post-exposure prophylaxis (PEP), men who have sex with men (MSM), Florida


Bacterial sexually transmitted infections (STIs), notably syphilis, gonorrhea, and chlamydia, have been increasing among men who have sex with men (MSM) in the United States. The rise has been attributed to various factors, including increased condomless sexual acts due to the high uptake of pre-exposure prophylaxis (PrEP) for HIV prevention. To address this concerning trend, post-exposure prophylaxis with doxycycline (Doxy-PEP) has emerged as a potential biomedical intervention. This study aimed to assess the effectiveness of Doxy-PEP in preventing bacterial STIs among MSM in Central Florida, a region with rising STI rates. A de-identified dataset from Pineapple Health Clinic in Orlando, Florida, was analyzed (n = 73) participants who received Doxy-PEP for bacterial STIs between July 01, 2022, and June 30, 2023. Results revealed elevated rates of any bacterial STI and syphilis incidence among both HIV-negative and HIV-positive individuals, contrary to expectations from previous literature. Notably, the HIV-positive cohort showed significantly higher incidence rates of syphilis. The study also found discrepancies in gonorrhea incidence and resistance profiles, raising questions about the effectiveness of Doxy-PEP against gonorrhea in this population. The older age of the HIV-positive cohort and differences in medication regimens further complicated the analysis. These findings suggest the effectiveness of Doxy-PEP may vary in real-world settings compared to controlled trials. Limitations include the small sample size, single healthcare clinic setting, differences in medication regimens, and the investigational status of Doxy-PEP. However, the study highlights the need for interventions considering diverse demographics and local antibiotic resistance patterns. Future research should explore these factors to develop effective strategies for reducing STI incidence among MSM in Central Florida.

Thesis Completion Year


Thesis Completion Semester


Thesis Chair

Castillo, Lopez


College of Sciences


Health Sciences

Thesis Discipline

Health Sciences



Access Status

Open Access

Length of Campus Access