Antibiotic consumption in HIV and PrEP populations with and without sexually transmitted infections: a population-based observational study.

Abstract

Background: Antimicrobial resistance is driven by antibiotic exposure. People living with HIV (PLWH) and PrEP users face high STI rates, but the magnitude of cumulative antibiotic exposure in these populations compared with the general population has not been well characterized.

Methods: This retrospective study (Madrid, 2024-2025) linked pharmacy and microbiology records of 562 325 adults. Participants were categorized into: (A) PLWH or PrEP users with documented rectal STI episodes in the context of active sexual health follow-up; (B) PrEP/PLWH without STIs; and (C) general population controls. Consumption was measured in Defined Daily Doses per 1000 persons-day (DHD) using propensity score overlap weights.

Results: Antibiotic use was significantly higher in Group A (95.3%) compared to Group B (35.4%) and Group C (27.3%) (P < 0.001). After weighting, individuals with documented rectal STI episodes (Group A) exhibited a markedly higher overall antibiotic exposure compared with general population controls (Group C) (adjusted rate ratio [RR]-DHD 4.67, 95% CI 4.41-4.94), driven by tetracyclines (RR-DHD 23.7), corresponding to a population rate equivalent to ∼1.1 seven-day doxycycline courses per person-year (a population-level metric, not an individual estimate). Group B consumption was 33% higher than controls (P = 0.004). Direct comparison confirmed that Group A's tetracycline use was 5.6-fold higher than Group B's (P < 0.001).

Conclusions: PLWH and PrEP users with documented rectal STI episodes experience markedly higher antibiotic exposure than the general population, driven primarily by tetracycline use. This disproportionate exposure in a small, identifiable subgroup supports targeted antimicrobial stewardship strategies in sexual health and HIV care settings, including systematic consumption monitoring, individualized doxy-PEP counselling, and integration of STI-focused populations into national AMR surveillance frameworks.