Threshold effects of doxycycline postexposure prophylaxis (PEP) on the gut resistome and microbiome: Evidence from change-point analyses

Doxy-PEP is associated with a dose-dependent enrichment of gut ARGs, with a threshold effect at ∼65 doses over 6 months and taxon-specific abundance shifts in the gut microbiome centered around 43 doses. These dose thresholds provide actionable data to optimize safe doxy-PEP implementation and highlight the need for monitoring strategies that mitigate AMR and microbiome disruption risks.