ESBL- E. coli extracellular vesicles mediate bacterial resistance to β-lactam and mediate horizontal transfer of bla CTX-M-55 .

Extracellular vesicles (EVs) have become the focus of research as an emerging method of horizontal gene transfer. In recent years, studies on the association between EVs and the spread of bacterial resistance have emerged, but there is a lack of research on the role of EVs secreted by ESBL-producing E. coli in the spread of β-lactam resistance. Therefore, in this study, the role of EVs secreted by ESBL-E. coli in the transmission of β-lactam resistance in E. coli was evaluated. The results showed that ESBL-EVs were protective against β-lactam antibiotic-susceptible bacteria, and this protective effect was dependent on the integrity of the EVs and showed dose- and time-dependent effects. At the same time, ESBL-EVs can also mediate the horizontal transmission of blaCTX-M-55 , and EVs-mediated gene transfer is selective, preferring to transfer in more closely related species. In this study, we demonstrated the important role of EVs in the transmission of β-lactam resistance in chicken ESBL-E. coli, and evaluated the risk of EVs-mediated horizontal gene transfer, which provided a theoretical basis for elucidating the mechanism of EVs-mediated resistance transmission.