Extracellular vesicles enhance the efficacy of ceftiofur against intracellular bacterial infections.

Bacterial infections pose a major threat to human health and economic stability. In particular, intracellular bacterial infections present significant clinical challenges due to antibiotic resistance and poor drug penetration. Therefore, there is an urgent need to develop novel therapeutic strategies to address the problem of intracellular bacterial infections. Extracellular bacterial vesicles become ideal delivery systems due to their natural targeting properties. Here, we developed a bacteria-derived extracellular vesicles (EVs)-based drug delivery platform to enhance the therapeutic efficacy of antibiotics against intracellular infections. EVs were successfully isolated and increased production from S. aureus by ultracentrifugation, then loaded with ceftiofur (CEF) via co-incubation. In vitro tests demonstrated the potent antibacterial activity of CEF, achieving complete growth inhibition within 24 h and a 4-log viability reduction in 4 h. Furthermore, confocal microscopy revealed efficient CEV internalization in IEC-6 cells, with 12-fold greater intracellular bacterial clearance than free CEF. In vivo, CEV-incorporated hydrogel (CEVH) significantly reduced both intra- and extracellular bacterial loads and accelerated wound healing. These findings demonstrate that bacterial EVs serve as a universal delivery platform to significantly enhance the efficacy of existing antibiotics against intracellular infections.