Silver-coated carbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect.
Silver-coated carbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect.
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DOI：
10.2147/ijn.s85219
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发表时间：
2015
影响因子：
8
通讯作者：
Pillai SR
中科院分区：
文献类型：
--
作者：
Dosunmu E;Chaudhari AA;Singh SR;Dennis VA;Pillai SR
研究了镀银碳纳米管(AgCNTs)对粘液型和非粘液型铜绿假单胞菌的体外抗菌活性及其潜在的作用模式。结果表明，AgCNTs对两种细菌均有一定的抗菌活性，最低抑菌浓度约为8µg/mL，说明铜绿假单胞菌对AgCNTs具有较高的敏感性。在相同的最低抑菌浓度下，AgCNTs对两种菌株也有杀菌作用。扫描和透射电子显微镜研究进一步表明，经AgCNTs处理的细胞大部分从光滑的杆状形态转变为具有破碎/损伤膜的解体细胞，导致细胞质内容物泄漏，产生鬼细胞。研究了AgCNTs对铜绿假单胞菌毒力、致病性、应激反应和外排泵相关基因表达的影响。实时定量聚合酶链式反应(qRT-PCR)显示，与未经处理的样品相比，AgCNTs暴露后，两株铜绿假单胞菌中rpos、rsmZ和oprD基因的表达水平均显著下调。这些结果表明，AgCNTs的作用机制可能与其影响铜绿假单胞菌细胞膜完整性、下调毒力基因表达、诱导全身应激和氧化应激有关。
The antimicrobial activity of silver-coated carbon nanotubes (AgCNTs) and their potential mode of action against mucoid and nonmucoid strains of Pseudomonas aeruginosa was investigated in vitro. The results showed that AgCNTs exhibited antimicrobial activity against both strains with minimum inhibitory concentrations of approximately 8 µg/mL, indicating a high sensitivity of P. aeruginosa to AgCNTs. AgCNTs were also bactericidal against both strains at the same minimum inhibitory concentration. Scanning and transmission electron-microscopy studies further revealed that a majority of the cells treated with AgCNTs transformed from smooth rod-shape morphology to disintegrated cells with broken/damaged membranes, resulting in leakage of cytoplasmic contents to produce ghost cells. The molecular effects of AgCNTs on P. aeruginosa genes involved in virulence and pathogenicity, stress response, and efflux pumps were evaluated for changes in their expression. Quantitative real-time PCR (qRT-PCR) showed that after exposure to AgCNTs, the expression levels of the rpoS, rsmZ, and oprD genes were significantly downregulated in both strains of P. aeruginosa compared to the untreated samples. These results suggest that the mechanism of action of AgCNTs may be attributed to their effect on cell-membrane integrity, downregulation of virulence-gene expression, and induction of general and oxidative stress in P. aeruginosa.