Effects of antibacterial mineral leachates on the cellular ultrastructure, morphology, and membrane integrity of <it>Escherichia coli </it>and methicillin-resistant <it>Staphylococcus aureus</it>
<p>Abstract</p> <p>Background</p> <p>We have previously identified two mineral mixtures, CB07 and BY07, and their respective aqueous leachates that exhibit <it>in vitro </it>antibacterial activity against a broad spectrum of pathogens. The present study asse...
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| Format: | Book |
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BMC,
2010-09-01T00:00:00Z.
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| Summary: | <p>Abstract</p> <p>Background</p> <p>We have previously identified two mineral mixtures, CB07 and BY07, and their respective aqueous leachates that exhibit <it>in vitro </it>antibacterial activity against a broad spectrum of pathogens. The present study assesses cellular ultrastructure and membrane integrity of methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) and <it>Escherichia coli </it>after exposure to CB07 and BY07 aqueous leachates.</p> <p>Methods</p> <p>We used scanning and transmission electron microscopy to evaluate <it>E. coli </it>and MRSA ultrastructure and morphology following exposure to antibacterial leachates. Additionally, we employed <it>Bac</it>light LIVE/DEAD staining and flow cytometry to investigate the cellular membrane as a possible target for antibacterial activity.</p> <p>Results</p> <p>Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging of <it>E. coli </it>and MRSA revealed intact cells following exposure to antibacterial mineral leachates. TEM images of MRSA showed disruption of the cytoplasmic contents, distorted cell shape, irregular membranes, and distorted septa of dividing cells. TEM images of <it>E. coli </it>exposed to leachates exhibited different patterns of cytoplasmic condensation with respect to the controls and no apparent change in cell envelope structure. Although bactericidal activity of the leachates occurs more rapidly in <it>E. coli </it>than in MRSA, LIVE/DEAD staining demonstrated that the membrane of <it>E. coli </it>remains intact, while the MRSA membrane is permeabilized following exposure to the leachates.</p> <p>Conclusions</p> <p>These data suggest that the leachate antibacterial mechanism of action differs for Gram-positive and Gram-negative organisms. Upon antibacterial mineral leachate exposure, structural integrity is retained, however, compromised membrane integrity accounts for bactericidal activity in Gram-positive, but not in Gram-negative cells.</p> |
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| Item Description: | 10.1186/1476-0711-9-26 1476-0711 |