NDM-5-carried outer membrane vesicles impair the efficacy of antibiotics against bacterial infections

The intensifying use of antimicrobials in the rapidly growing livestock industry has heightened concerns over the proliferation of antibiotic resistance, particularly among <i>Enterobacteriaceae</i> producing β-lactamase. Elucidating the role of β-lactamase could unlock novel strategies to combat drug-resistant <i>Enterobacteriaceae</i> in livestock and poultry farming. Outer membrane vesicles (OMVs) produced by gram-negative bacteria have the ability to encapsulate and transport components derived from their parental bacteria. This raises the intriguing possibility that OMVs from drug-resistant bacteria could harbor drug-resistance enzymes, thereby conferring protection to susceptible bacteria against antibiotics. Here, we successfully extracted OMVs from New Delhi metallo-β-lactamase-5 (NDM-5)-expressing <i>Escherichia coli</i> and confirmed that these vesicles indeed carry NDM-5 protein. Furthermore, bacterial protection assays showed that these OMVs could cause sensitive bacteria treated with meropenem to restore growth activity, and the degradation of meropenem by the OMVs was verified using high-performance liquid chromatography. Lastly, the survival rate of the OMVs intervention group was significantly lower than that of the drug-treated group in a <i>Galleria mellonella</i> larvae infection model, validating the protective effect of these OMVs on sensitive bacteria and increasing their tolerance to meropenem. These findings illustrate that OMVs can serve as vehicles for resistance-related factors, thereby promoting antibiotic tolerance in susceptible bacteria.