Antimicrobial use for the treatment of bacterial sexually transmitted infections among doxycycline post-exposure prophylaxis (DoxyPEP) users in Milan, Italy—right-to-reply

We thank Kenyon for his thoughtful comments on our analysis of antimicrobials use among DoxyPEP users in Milan.1 We agree on two important points. Firstly, further data on the effectiveness of DoxyPEP in preventing symptomatic infections, as well as data on antibiotic consumption across different service models, are needed. Secondly, the routine screening of asymptomatic Neisseria gonorrhoeae and Chlamydia trachomatis (NG/CT) in men who have sex with men (MSM) is the subject of an ongoing debate, with Belgian policies moving away from screening.2,3 Our study addressed a different question: what impact does a targeted DoxyPEP strategy, involving ongoing routine testing as recommended by our local and most international guidelines, have on antimicrobial consumption? In this context, which involved testing every 3–6 months at rectal, urethral, and pharyngeal sites and treating all asymptomatic and symptomatic individuals, we observed a significant reduction in the number of days of treatment (DOT) among DoxyPEP users compared to the expected DOT had DoxyPEP not been introduced: ceftriaxone 1.26 versus 4.85 per 1000 person-days; benzylpenicillin 0.37 versus 1.86; and doxycycline 3.21 versus 24.71. Even after accounting for prophylactic doxycycline use, total doxycycline exposure remained well below what would be expected for treatment alone without DoxyPEP. It should be noted that DoxyPEP was only recommended for use in cases of concentrated exposure (i.e. >5 partners within a short period), which could explain the different results reported in contexts where DoxyPEP is recommended after each exposure, potentially leading to daily use.4