Outer-membrane vesicles (OMVs) produced bydeliver bacterial components to host cells, provide a mechanism for stabilization of secreted components and may allow the bacteria to exert 'long-range' effects in the gastric niche, promoting persistence. In addition to their well-characterized host cell interactions, membrane vesicles improve stress survival in other bacterial species, and are constitutively produced by both pathogenic and non-pathogenic bacteria. We aimed to determine whether OMVs could improvesurvival of a range of stressors. The effects of purified OMVs on the resistance ofto a range of environmental and antimicrobial stresses were determined using growth curves and survival assays. Addition of purified OMVs tocultures provided dose-dependent protection against hydrogen peroxide-mediated killing. Supplementation with OMVs also partially protectedagainst the bactericidal effects of the antibiotics clarithromycin and levofloxacin, but not against amoxicillin nor metronidazole. Addition of purified OMVs allowedto grow in the presence of inhibitory concentrations of the antimicrobial peptide LL-37. In the presence of 50 µg OMVs ml, significantly enhancedgrowth was observed at higher LL-37 concentrations compared with lower LL-37 concentrations, suggesting that OMV-LL-37 interactions might facilitate release of growth-promoting nutrients. Taken together, these data indicate that production of membrane vesicles could helpto survive exposure to antibiotics and host antimicrobial defences during infection.
Authors
Murray, Benjamin Oliver; Dawson, Robin Andrew; Alsharaf, Lolwah Mohammad; Anne Winter, Jody