CRISPR-Cas systems as precision antimicrobials: Reversing the tide of antimicrobial resistance

Antimicrobial resistance (AMR) has escalated into a global health crisis, with resistant pathogens causing over 1.2 million direct deaths annually and threatening to render modern medicine unsustainable. This review provides a comprehensive and updated synthesis of CRISPR-Cas-based antimicrobial strategies with a unique focus on: (i) critical comparison with conventional antibiotics and emerging alternatives; (ii) quantitative evaluation of delivery platforms; (iii) novel strategies including AI-optimized guide design and the ATTACK-CreTA system; (iv) comprehensive analysis of ecological risks; and (v) technology readiness level assessments for clinical translation. The CRISPR-Cas system, originally discovered as a bacterial adaptive immune mechanism, has been repurposed as a programmable precision tool to combat AMR by selectively targeting and eliminating resistance genes. We systematically evaluate the mechanistic diversity of Cas effectors, from DNA-cleaving Cas9 and Cas3 to RNA-targeting Cas13, and their application in reversing resistance phenotypes in WHO priority pathogens. We critically assess emerging delivery platforms, including engineered bacteriophages, conjugative plasmids, nanoparticles, and outer membrane vesicles, quantitatively comparing their delivery efficiency, payload capacity, and biosafety profiles. Novel strategies such as CRISPR interference (CRISPRi) for gene silencing without genomic cleavage, the ATTACK-CreTA system for enhanced bactericidal activity, and AI-driven optimization of guide RNA design are examined with appropriate caveats. We comprehensively address clinical translation challenges including immunogenicity, pharmacokinetics/pharmacodynamics, manufacturing scalability, regulatory pathways, and bacterial resistance mechanisms including anti-CRISPR proteins. No CRISPR-based antimicrobial has yet received regulatory approval, and we critically evaluate the gap between proof-of-concept and clinical utility. A detailed roadmap for clinical development is proposed. By integrating recent advances in Cas protein engineering, delivery technologies, and diagnostic applications, this review positions CRISPR-Cas systems as next-generation precision therapeutics capable of both treating resistant infections and curtailing the spread of AMR across clinical and environmental settings.