Membrane vesicles from antibiotic-resistant Staphylococcus aureus transfer antibiotic-resistance to antibiotic-susceptible Escherichia coli

Aim Bacteria naturally produce membrane vesicles (MVs), which have been shown to contribute to the spread of multi-drug resistant bacteria (MDR) by delivering antibiotic-resistant substances to antibiotic-susceptible bacteria. Here, we aim to show that MVs from Gram-positive bacteria are capable of transferring beta-lactam antibiotic-resistant substances to antibiotic-sensitive Gram-negative bacteria. Materials and Methods MVs were collected from a methicillin-resistant strain of Staphylococcus aureus (MRSA) and vesicle-mediated fusion with antimicrobial-sensitive Escherichia coli (RC85). It was performed by exposing the bacteria to the MVs to develop antimicrobial-resistant E. coli (RC85-T). Results The RC85-T exhibited a higher resistance to beta-lactam antibiotics compared to the parent strain. Although the secretion rates of the MVs from RC85-T and the parent strain were nearly equal, the beta-lactamase activity of the MVs from RC85-T was 12-times higher than that of MVs from the parent strain, based on equivalent protein concentrations. Moreover, MVs secreted by RC85-T were able to protect beta-lactam-susceptible E. coli from beta-lactam antibiotic-induced growth inhibition in a dose-dependent manner. Conclusion MVs play a role in transferring substances from Gram-positive to Gram-negative bacteria, shown by the release of MVs from RC85-T that were able to protect beta-lactam-susceptible bacteria from beta-lactam antibiotics.