Synergistic combinations of antimicrobial peptides and conventional antibiotics: A strategy to delay resistance emergence in World Health Organization priority bacteria

Antimicrobial resistance represents one of the most pressing global health challenges of the 21st century, significantly compromising the efficacy of conventional antibiotics. In response to this crisis, the World Health Organization has updated its 2024 list of priority bacterial pathogens-classified into critical-, high-, and medium-risk groups-based on their resistance mechanisms, clinical impact, and global dissemination. This comprehensive review explores the emerging therapeutic potential of antimicrobial peptides (AMPs) when used in synergistic combinations with conventional antibiotics. By dissecting the mechanistic interplay-ranging from membrane disruption and efflux pump inhibition to biofilm penetration and intracellular antibiotic delivery-we provide a structured analysis of how these dual strategies overcome specific resistance barriers. Special emphasis is given to the World Health Organization-designated pathogens such as Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus (methicillin-resistant/vancomycin-resistant), Enterococcus faecium, Salmonella spp., Shigella spp., and Mycobacterium tuberculosis. Supported by extensive in vitro and in vivo data, this review catalogs dozens of successful AMP-antibiotic pairings, highlighting their fractional inhibitory concentration indices, clinical relevance, and implications for translational development. The evidence presented demonstrates that AMPs not only potentiate antibiotic action but also extend the useful lifespan of existing drugs while reducing toxicity. These findings support the advancement of AMP-based combination therapies as a next-generation strategy to contain resistance and restore the effectiveness of the antimicrobial arsenal. SIGNIFICANCE STATEMENT: Antimicrobial resistance remains a global health emergency, especially among World Health Organization 2024 priority pathogens. This review highlights the therapeutic promise of synergistic combinations between antimicrobial peptides and conventional antibiotics, offering a rational strategy to restore efficacy, overcome resistance mechanisms, and extend the clinical utility of existing drugs. By bridging microbiology, pharmacology, and translational medicine, this work provides timely insights for researchers and policymakers seeking innovative solutions to combat multidrug-resistant infections.