Exploiting a conjugative CRISPR/Cas9 system to eliminate plasmid harbouring the mcr-1 gene from Escherichia coli

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacterial conjugation facilitates the spread of multi-drug resistance plasmids, complicating infectious disease treatment.
• The plasmid-borne colistin resistance gene, mcr-1, has emerged globally in Gram-negative pathogens since 2016.
• Eliminating mcr-1 plasmids is crucial for restoring polymyxin effectiveness, as these are last-resort antibiotics.

Purpose of the Study:

• To develop a novel strategy for eliminating mcr-1 carrying plasmids from bacteria.
• To assess the efficacy of a host-independent conjugative plasmid and CRISPR/Cas9 system in removing resistance genes.
• To investigate the potential of this system to re-sensitize bacteria to antibiotics and confer immunity.

Main Methods:

• Construction of a host-independent conjugative plasmid.
• Application of an engineered CRISPR/Cas9 system to target and remove mcr-1 plasmids.
• Evaluation of the plasmid's ability to eliminate resistance genes and confer immunity.

Main Results:

• The engineered conjugative plasmid successfully removed mcr-1 harboring plasmids from bacteria.
• Recipient bacteria were re-sensitized to antibiotics after plasmid removal.
• The system conferred immunity against the mcr-1 gene in recipient cells.

Conclusions:

• A novel conjugative plasmid system effectively eliminates mcr-1 resistance plasmids, offering a new tool against antibiotic resistance.
• This strategy restores antibiotic sensitivity and provides immunity, addressing the critical challenge of mcr-1 spread.
• The developed system presents a promising approach to counteract the global threat of drug-resistant bacterial infections.