Emerson Ray J, Camesano Terri A
Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, USA.
Appl Environ Microbiol. 2004 Oct;70(10):6012-22. doi: 10.1128/AEM.70.10.6012-6022.2004.
Microbial infections of medical implants occur in more than 2 million surgical cases each year in the United States alone. These increase patient morbidity and mortality, as well as patient cost and recovery time. Many treatments are available, but none are guaranteed to remove the infection. In many cases, the device infections are caused by the adhesion of microbes to the implant, ensuing growth, pathogenesis, and dissemination. The purpose of this work is to examine the initial events in microbial adhesion by simulating the approach and contact between a planktonic cell, immobilized on an atomic force microscope (AFM) cantilever, and a biomaterial or biofilm substrate. The two model microbes used in this study, Candida parapsilosis (ATCC 90018) and Pseudomonas aeruginosa (ATCC 10145), were chosen for both their clinical relevance and their ease of acquisition and handling in the laboratory setting. Attractive interactions exist between C. parapsilosis and both unmodified silicone rubber and P. aeruginosa biofilms. Using C. parapsilosis cells immobilized on AFM cantilevers with a silicone substrate, we have measured attractive forces of 4.3 +/- 0.25 nN in the approach portion of the force cycle. On P. aeruginosa biofilms, the magnitude of the attractive force decreases to 2.0 +/- 0.40 nN and is preceded by a 2.0-nN repulsion at approximately 75 nm from the cell surface. These data suggest that C. parapsilosis may adhere to both silicone rubber and P. aeruginosa biofilms, possibly contributing to patient morbidity and mortality. Characterization of cell-biomaterial and cell-cell interactions allows for a quantitative link between the physicomechanical and physicochemical properties of implant materials and the nanoscale interactions leading to microbial colonization and infection.
仅在美国，每年就有超过200万例外科手术病例发生医用植入物的微生物感染。这些感染会增加患者的发病率和死亡率，以及患者的费用和恢复时间。虽然有多种治疗方法，但没有一种能保证消除感染。在许多情况下，器械感染是由微生物粘附到植入物上，随后生长、致病和扩散引起的。这项工作的目的是通过模拟固定在原子力显微镜（AFM）悬臂上的浮游细胞与生物材料或生物膜基质之间的接近和接触，来研究微生物粘附的初始事件。本研究中使用的两种模式微生物，近平滑念珠菌（ATCC 90018）和铜绿假单胞菌（ATCC 10145），因其临床相关性以及在实验室环境中易于获取和处理而被选用。近平滑念珠菌与未改性的硅橡胶和铜绿假单胞菌生物膜之间存在吸引力相互作用。使用固定在带有硅酮基质的AFM悬臂上的近平滑念珠菌细胞，我们在力循环的接近部分测量到了4.3±0.25 nN的吸引力。在铜绿假单胞菌生物膜上，吸引力的大小降至2.0±0.40 nN，并且在距离细胞表面约75 nm处有一个2.0 nN的排斥力。这些数据表明，近平滑念珠菌可能粘附于硅橡胶和铜绿假单胞菌生物膜，这可能导致患者的发病率和死亡率。细胞与生物材料以及细胞与细胞相互作用的表征，使得植入材料的物理机械和物理化学性质与导致微生物定植和感染的纳米级相互作用之间建立了定量联系。
