Mukherjee Pranab K, Chand David V, Chandra Jyotsna, Anderson James M, Ghannoum Mahmoud A
Center for Medical Mycology, Department of Dermatology, University Hospitals of Cleveland and Case Western Reserve University, OH 44106-5028, USA.
Mycoses. 2009 Sep;52(5):440-6. doi: 10.1111/j.1439-0507.2008.01632.x. Epub 2008 Dec 9.
Biofilm formation plays an integral role in catheter-associated bloodstream infections caused by Candida albicans. Biofilms formed on catheters placed intravenously are exposed to shear stress caused by blood flow. In this study, we investigated whether shear stress affects the ability of C. albicans to form biofilms. Candida biofilms were formed on catheter discs and exposed to physiological levels of shear stress using a rotating disc system (RDS). Control biofilms were grown under conditions of no flow. Tetrazolium (XTT) assay and dry weight (DW) measurements were used to quantify metabolic activity and biofilm mass respectively. Confocal scanning laser microscopy (CSLM) was used to evaluate architecture and biofilm thickness. After 90 min, cells attached under no-flow exhibited significantly greater XTT activity and DW than those under shear. However, by 24 h, biofilms formed under both conditions had similar XTT activities and DW. Interestingly, thickness of biofilms formed under no-flow was significantly greater after 24 h than of those formed under shear stress, demonstrating that shear exposure results in thinner, but denser biofilms. These studies suggest that biofilm architecture is modulated by shear in a phase-dependent manner.
生物膜形成在白色念珠菌引起的导管相关血流感染中起着不可或缺的作用。静脉内放置的导管上形成的生物膜会受到血流引起的剪切应力作用。在本研究中，我们调查了剪切应力是否会影响白色念珠菌形成生物膜的能力。念珠菌生物膜在导管圆盘上形成，并使用旋转圆盘系统（RDS）使其暴露于生理水平的剪切应力下。对照生物膜在无流动条件下生长。分别使用四唑盐（XTT）测定法和干重（DW）测量来量化代谢活性和生物膜质量。共聚焦扫描激光显微镜（CSLM）用于评估结构和生物膜厚度。90分钟后，无流动条件下附着的细胞比有剪切应力条件下的细胞表现出显著更高的XTT活性和DW。然而，到24小时时，两种条件下形成的生物膜具有相似的XTT活性和DW。有趣的是，24小时后无流动条件下形成的生物膜厚度明显大于有剪切应力条件下形成的生物膜，这表明暴露于剪切应力会导致生物膜更薄但更致密。这些研究表明，生物膜结构在不同阶段受到剪切应力的调节。
