Membrane vesicles derived from Enterococcus faecalis promote the co-transfer of important antibiotic resistance genes located on both plasmids and chromosomes.

This article focuses on the role of membrane vesicles (MVs) in mediating the horizontal transfer of antibiotic resistance genes (ARGs) in Gram-positive bacteria, specifically Enterococcus faecalis. The study demonstrates that MVs derived from a linezolid-resistant E. faecalis strain of swine origin (CQ20) carry two plasmids and a chromosome-located transposon (Tn6674) containing the optrA gene, which confers resistance to phenicol and oxazolidinone antibiotics. These MVs successfully transferred ARGs to linezolid-susceptible E. faecalis and Enterococcus faecium strains of human origin, but not to Escherichia coli, indicating species-specific transfer. Furthermore, vesiculants that acquired ARGs retained the ability to disseminate these genes via MVs, suggesting that MVs represent a novel and efficient mechanism for ARG spread among Gram-positive bacteria, including interspecies transfer from animal to human pathogens.