Outer membrane vesicles secreted from isolate disseminating the resistance gene to Enterobacteriaceae.

, a significant respiratory pig pathogen, is causing substantial losses in the global swine industry. The resistance spectrum of is expanding, and multidrug resistance is a severe issue. Horizontal gene transfer (HGT) plays a crucial role in the development of the bacterial genome by facilitating the dissemination of resistance determinants. However, the horizontal transfer of resistance genes via -derived outer membrane vesicles (OMVs) has not been previously reported. In this study, we used Illumina NovaSeq and PacBio SequeI sequencing platforms to determine the whole genome sequence of GD2107, a multidrug-resistant (MDR) isolate from China. We detected a plasmid in the isolate named pGD2107-1; the plasmid was 5,027 bp in size with 7 putative open reading frames (ORF) and included the floR resistance genes. The carriage of resistance genes in OMVs was identified using a polymerase chain reaction (PCR) assay, and then we thoroughly evaluated the influence of OMVs on the horizontal transfer of drug-resistant plasmids. The transfer of the plasmid to recipient bacteria via OMVs was confirmed by PCR. In growth competition experiments, all recipients carrying the pGD2107-1 plasmid exhibited a fitness cost compared to the corresponding original recipients. This study revealed that OMVs could mediate interspecific horizontal transfer of the resistance plasmid pGD2107-1 into recipient strains and significantly enhance the resistance of the transformants. In summary, -OMVs play the pivotal role of vectors for dissemination of the floR gene spread and may contribute to more antimicrobial resistance gene transfer in other Enterobacteriaceae.