McMaster researchers reported preclinical evidence for a phage therapy that targets Crohn’s disease–associated inflammatory E. coli strains while aiming to preserve broader gut microbiome balance. Using bacteriophages designed to attenuate virulence of adherent-invasive E. coli (AIEC), the team showed improved colitis outcomes and improved responses to low-dose corticosteroids in a mouse model. Published in Science Translational Medicine, the study describes a strategy focused on disabling harmful bacterial behavior rather than broadly killing bacteria with non-specific antibiotics. The investigators highlighted that phage treatment can align with personalized microbial therapeutics by reducing virulence mechanisms without substantially disrupting microbial equilibrium. The approach also provides a potential path to enhance existing Crohn’s regimens while lowering steroid side effects, though the evidence remains preclinical and centered on AIEC as a mechanistic test case.