Reinvigorating AMR resilience: leveraging CRISPR-Cas technology potentials to combat the 2024 WHO bacterial priority pathogens for enhanced global health security-a systematic review.

Background: Antimicrobial resistance (AMR) poses a global health threat, particularly in low- and middle-income countries (LMICs). Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system technology offers a promising tool to combat AMR by targeting and disabling resistance genes in WHO bacterial priority pathogens. Thus, we systematically reviewed the potential of CRISPR-Cas technology to address AMR.

Methods: This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive literature search was conducted using the Scopus and PubMed databases, focusing on publications from 2014 to June 2024. Keywords included "CRISPR/Cas," "antimicrobial resistance," and "pathogen." The eligibility criteria required original studies involving CRISPR/Cas systems that targeted AMR. Data were extracted from eligible studies, qualitatively synthesized, and assessed for bias using the Joanna Briggs Institute (JBI)-standardized tool.

Results: Data from 48 eligible studies revealed diverse CRISPR-Cas systems, including CRISPR-Cas9, CRISPR-Cas12a, and CRISPR-Cas3, targeting various AMR genes, such as blaOXA-232, blaNDM, blaCTX-M, ermB, vanA, mecA, fosA3, blaKPC, and mcr-1, which are responsible for carbapenem, cephalosporin, methicillin, macrolide, vancomycin, colistin, and fosfomycin resistance. Some studies have explored the role of CRISPR in virulence gene suppression, including enterotoxin genes, tsst1, and iutA in Staphylococcus aureus and Klebsiella pneumoniae. Delivery mechanisms include bacteriophages, nanoparticles, electro-transformation, and conjugative plasmids, which demonstrate high efficiency in vitro and in vivo. CRISPR-based diagnostic applications have demonstrated high sensitivity and specificity, with detection limits as low as 2.7 × 10 CFU/mL, significantly outperforming conventional methods. Experimental studies have reported significant reductions in resistant bacterial populations and complete suppression of the targeted strains. Engineered phagemid particles and plasmid-curing systems have been shown to eliminate IncF plasmids, cured plasmids carrying vanA, mcr-1, and blaNDM with 94% efficiency, and restore antibiotic susceptibility. Gene re-sensitization strategies have been used to restore fosfomycin susceptibility in E. coli and eliminate blaKPC-2-mediated carbapenem resistance in MDR bacteria. Whole-genome sequencing and bioinformatics tools have provided deeper insights into CRISPR-mediated defense mechanisms. Optimization strategies have significantly enhanced gene-editing efficiencies, offering a promising approach for tackling AMR in high-priority WHO pathogens.

Conclusions: CRISPR-Cas technology has the potential to address AMR across priority WHO pathogens. While promising, challenges in optimizing in vivo delivery, mitigating potential resistance, and navigating ethical-regulatory barriers must be addressed to facilitate clinical translation.