Background
DoxyPEP proved to be effective in preventing bacterial sexually transmitted infections (STIs) and the Centers for Diseases Control and Prevention (CDC) recommended it in men who have sex with men (MSM) and transgender women (TGW) who have had at least one infection in the previous 12 months. However, the risk of antibiotic overuse and the potential spread of antimicrobial resistance led many scientific societies to issue more cautious and restrictive position statements. Aim of this study is to evaluate if CDC recommendations would be appropriate in a cohort of PrEP users assessing factors that describe individuals who might benefit most from doxyPEP.
Methods
Milano Checkpoint is a community-based, peer-led service that provides medical assistance to one of the largest PrEP cohorts in Italy. Individuals who had at least one STI from July 2022 to June 2023 were selected. Demographic and behavioral features were collected. The diagnoses of syphilis, Chlamydia, and gonorrhea in the following 12 months were evaluated: potential antibiotic overuse was defined if no STIs were recorded during the follow up. Descriptive statistics were used to depict study population. Adjusted Poisson regression was used to describe variables associated to appropriate doxyPEP prescribing conditions (i.e., no antibiotic overuse).
Results
The analysis included 251 individuals who had at least one STI in the previous year (90 Chlamydia, 83 gonorrhea, 26 syphilis, 52 had two or more infections). The majority was represented by men (97.6%), born in Italy (78.9%), white (85.6%), with a university degree (66.5%) (Table 1). During the follow up 129 STIs were registered (55 Chlamydia, 43 gonorrhea, 31 syphilis); 28 individuals (11.2%) had two or more infections. If doxyPEP had been taken, 85 (95%CI 70-98) infections would have been avoided. Nevertheless, 162 individuals (64.5%) had no further infections and would have had antibiotic overuse if they had taken doxyPEP. Adjusted Poisson regression found that the number of condomless intercourses was the only variable associated to an appropriate doxyPEP prescription (IRR 1.16 per 10 contacts, 95%CI 1.06-1.28, p=0.002).
Conclusions
Our data suggest that CDC recommendations for doxyPEP prescription could be exceedingly broad leading to a considerable antibiotic overuse. Adding the evaluation of further behavioral variables could refine the selection of individuals who might benefit most from doxyPEP.