Bacteriophage therapy in the antibiotic resistance era: mechanistic promise, clinical evidence, and system-level barriers

Antimicrobial resistance (AMR) poses a growing global health threat, progressively undermining the clinical effectiveness of conventional antibiotic therapies. Despite their proven efficacy and standardized clinical frameworks, antibiotics exert strong selective pressures that accelerate resistance, disrupt host microbiota, and limit treatment options for chronic, biofilm-associated, and multidrug-resistant infections. Bacteriophage therapy has re-emerged as a potential adjunct or alternative approach, offering pathogen-specific antibacterial activity, preservation of commensal microbiota, and the capacity for co-evolution with bacterial hosts. This focused review critically compares antibiotics and bacteriophage therapy across mechanistic foundations, preclinical and clinical evidence, translational readiness, and real-world implementation challenges. While preclinical models consistently demonstrate robust antibacterial activity of bacteriophages, clinical evidence remains heterogeneous, with few randomized controlled studies available. Key system-level barriers, including regulatory inconsistency, manufacturing complexity, and lack of standardization, currently limit widespread clinical integration. Rather than positioning bacteriophages as replacements for antibiotics, this review emphasizes their potential role as complementary agents, particularly through bacteriophage-antibiotic synergy, to enhance treatment efficacy and mitigate resistance. Addressing methodological gaps, standardizing clinical trial designs, and developing integrated stewardship models will be critical to defining the future role of bacteriophage therapy in modern infectious disease management.