Triggering toxicity: How antibiotics can enhance the release of outer membrane vesicles from Escherichia coli during sepsis.

OMVs are spherical buds derived from the outer membrane of Gram-negative bacteria, containing lipopolysaccharide (LPS) and phospholipids, proteins, nucleic acids, peptidoglycan, and other cellular molecules. Some of those molecules, such as LPS and peptidoglycan associated lipoprotein (Pal), have been shown to be toxic and to contribute to sepsis-related inflammation. While OMVs are released constitutively from Gram-negative bacteria, environmental factors like temperature changes, stress, and antibiotics can enhance OMV release. We proposed that some antibiotics, such as beta lactams that target the peptidoglycan layer of the cell, enhance OMV release more than other types of antibiotics. We used ultracentrifugation, immunoblotting, and nanoparticle tracking analysis to purify, detect, and roughly quantify OMV release from Escherichia coli in the presence of different antibiotics. Preliminary results support our hypothesis, although data collection is ongoing. Finally, we propose a novel use of released OMVs as molecular biomarkers for bacterial sepsis.