[pELF-type linear plasmids and antimicrobial resistance in enterococci].

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Enterococci are significant opportunistic pathogens, with multidrug-resistant strains posing a major public health threat.
• Antimicrobial resistance gene (ARG) dissemination in enterococci is primarily driven by conjugative plasmids.
• Previously, enterococcal plasmids were exclusively considered circular, overlooking potential linear forms.

Purpose of the Study:

• To investigate the role of a novel family of linear plasmids, termed pELF-type, in the dissemination of antimicrobial resistance in enterococci.
• To characterize the structure, function, and epidemiological distribution of pELF-type linear plasmids.
• To understand the contribution of these plasmids to the emergence of multidrug-resistant Enterococcus faecium.

Main Methods:

• Molecular epidemiology
• Phenotypic analysis
• Transcriptomic analysis
• Plasmid identification and characterization

Main Results:

• Identification and characterization of pELF1, a linear plasmid with hybrid terminal structures conferring vancomycin resistance (VanA and VanM).
• Demonstration of pELF-type plasmids mediating interspecies transfer of vancomycin resistance genes between different enterococcal species.
• Evidence of global distribution of pELF-type linear plasmids in Enterococcus faecium, with conserved backbones and host adaptation.
• Discovery of pELF-type plasmids acquiring additional resistance genes, leading to vancomycin and linezolid co-resistance.

Conclusions:

• pELF-type linear plasmids are critical vehicles for ARG dissemination in Enterococcus faecium.
• These plasmids contribute significantly to the development of multidrug resistance in enterococci.
• The findings highlight the need to include pELF-type linear plasmids in surveillance and intervention strategies against antimicrobial resistance.