Bactericidal effect of gentamicin-induced membrane vesicles derived fromPseudomonas aeruginosaPAO1 on gram-positive bacteria

Abstract

Previous studies have shown that gentamicin-induced membrane vesicles (g-MVs) from Pseudomonas aeruginosa PAO1 possess both the antibiotic (gentamicin) and a potent peptidoglycan hydrolase (PGase; autolysin) that is effective in killing gram-negative pathogens. This present study evaluated the therapeutic potential of g-MVs against four gram-positive bacteria. Bactericidal assays and electron microscopy of thin sections revealed that Bacillus subtilis 168 and Staphylococcus aureus D2C were susceptible to killing mediated by g-MVs, Listeria monocytogenes ATCC 19113 was slightly susceptible, whereas Enterococcus hirae ATCC 9790 was unaffected. g-MVs were generally more effective against the bacteria than was soluble gentamicin, suggesting they could have more killing power than natural membrane vesicles containing no antibiotic. Electron microscopy and hydrophobic interaction chromatography showed that more membrane vesicles (MVs) initially attached to B. subtilis (hydrophilic) than to predominantly hydrophobic E. hirae, L. monocytogenes, and S. aureus. Zymograms containing murein sacculi as an enzyme substrate illustrated that all organisms except E. hirae were sensitive to the 26-kDa autolysin to varying degrees. Peptidoglycan O-acetylation did not influence susceptibility to MV-mediated lysis. Though not universally effective, the g-MV delivery system remains a promising therapeutic alternative for specific gram-positive infections.

The surface physicochemistry and adhesiveness of Shewanella are affected by their surface polysaccharides

“…HIC was carried out as described by MacDonald & Beveridge (2002). Two sets of Bio-Rad Econo columns were used in the assay.…”

Lesions in Teichoic Acid Biosynthesis in Staphylococcus aureus Lead to a Lethal Gain of Function in the Otherwise Dispensable Pathway

“…Cell wall isolation and phosphate content determination were carried out as described previously (6). Briefly, cell wall was extracted by boiling in sodium dodecyl sulfate (26), DNase, and RNase and trypsin treated (22) and mineralized (2). Wall phosphate content was assayed by absorbance using KH 2 PO 4 as a standard (12).…”

DNA-containing membrane vesicles of Pseudomonas aeruginosa PAO1 and their genetic transformation potential

“…Since the production of MVs is a common phenomenon, since they represent a significant metabolic expense to cells and since they are produced by a multitude of Gram-negative bacteria (Li et al, 1998), they must serve a significant purpose. Some possible roles have been suggested, such as predation Kadurugamuwa et al, 1998;Li et al, 1998;MacDonald & Beveridge, 2002), enhanced virulence Abbreviations: KDO, 3-deoxy-D-manno-octulosonic acid (3-deoxy-Dmanno-2-octulosonic acid); MVs, membrane vesicles; n-MVs, natural membrane vesicles; OM, outer membrane; PM, plasma membrane; p-MVs, MVs from PAO1/pAK1900; TEM, transmission electron microscopy.…”

“…This DNA somehow migrates from the cytoplasm, through the plasma membrane (PM) to the periplasm and (along with other periplasmic materials; Kadurugamuwa & Beveridge, 1995) is encapsulated within an MV. Once liberated from the cell, foreign autolysins (Li et al, 1996(Li et al, , 1998Kadurugamuwa et al, 1998;MacDonald & Beveridge, 2002) or b-lactamases (Ciofu et al, 2000) can be delivered to other bacteria. There are certain advantages for DNA to encapsulate itself in MVs.…”