Effects of antibacterial mineral leachates on the cellular ultrastructure, morphology, and membrane integrity of Escherichia coli and methicillin-resistant Staphylococcus aureus
Effects of antibacterial mineral leachates on the cellular ultrastructure, morphology, and membrane integrity of Escherichia coli and methicillin-resistant Staphylococcus aureus
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DOI：
10.1186/1476-0711-9-26
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发表时间：
2010-01-01
影响因子：
5.7
通讯作者：
Haydel, Shelley E.
中科院分区：
文献类型：
--
作者：
Otto, Caitlin C.;Cunningham, Tanya M.;Haydel, Shelley E.
背景资料：我们以前已经确定了两种矿物混合物，CB 07和BY 07，以及它们各自的水浸出液，表现出对广谱病原体的体外抗菌活性。本研究旨在评估CB 07和BY 07浸提液暴露后耐甲氧西林金黄色葡萄球菌（MRSA）和大肠杆菌的细胞超微结构和膜完整性。大肠杆菌和MRSA的超微结构和形态暴露后的抗菌浸出液。此外，我们还采用Baclight LIVE/DEAD染色和流式细胞术研究了细胞膜作为抗菌活性的可能靶点。大肠杆菌和MRSA暴露于抗菌矿物质浸出液后显示细胞完整。MRSA的TEM图像显示细胞质内容物的破坏、变形的细胞形状、不规则的膜和分裂细胞的变形的隔膜。E.暴露于浸出液的大肠杆菌表现出与对照不同的细胞质凝聚模式，细胞包膜结构没有明显变化。虽然渗滤液的杀菌活性在E. LIVE/DEAD染色结果显示，E.大肠杆菌保持完整，而MRSA膜透性暴露后的沥滤液。结论：这些数据表明，沥滤液的抗菌作用机制不同的革兰氏阳性和革兰氏阴性菌。在抗菌矿物浸出液暴露后，结构完整性得以保留，然而，受损的膜完整性导致革兰氏阳性细胞中的杀菌活性，而不是革兰氏阴性细胞。
Background: We have previously identified two mineral mixtures, CB07 and BY07, and their respective aqueous leachates that exhibit in vitro antibacterial activity against a broad spectrum of pathogens. The present study assesses cellular ultrastructure and membrane integrity of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli after exposure to CB07 and BY07 aqueous leachates.Methods: We used scanning and transmission electron microscopy to evaluate E. coli and MRSA ultrastructure and morphology following exposure to antibacterial leachates. Additionally, we employed Baclight LIVE/DEAD staining and flow cytometry to investigate the cellular membrane as a possible target for antibacterial activity.Results: Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging of E. coli 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 E. coli 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 E. coli than in MRSA, LIVE/DEAD staining demonstrated that the membrane of E. coli remains intact, while the MRSA membrane is permeabilized following exposure to the leachates.Conclusions: 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.