(50f) Staphylococcus Epidermidis Adhesion on Modified Silicone Rubber

Authors: 
Cao, T., Wayne State University
Wang, A., Wayne State University
Liang, X., Wayne State University
Salley, S. O., Wayne State University
Mcallister II, J. P., Wayne State University
Tang, H., Wayne State University


Cerebrospinal fluid (CSF) shunts for the treatment of hydrocephalus contain intracranial catheters made exclusively of silicone rubber. The development of bacterial adhesion and colonization on the catheter surface leads to frequent CSF shunt complications, and 30-40% mortality rate from post-operative infections have been reported. Modifications of silicone surface have been attempted in order to reduce the incidence of shunt infections. However, the influence of surface hydrophobicity, roughness, and various functional groups on bacterial adhesion has not been fully elucidated and conflicting results have been reported. The objective of this study was to perform a systematic analysis of the effect of silicone surface modification on bacterial adhesion and microbial colonization. Silicone was modified with different biopolymers and silanes, including: heparin, hyaluronan, octadecyltrichlorosilane (OTS), and perfluorodecyltrichlorosilane (FAS), in an attempt to provide a stable, and biocompatible surface with different degrees of hydrophobicity, roughness and functional groups. The quality and stability of these biopolymer and self-assembled monolayer coatings were examined by contact angle, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Contact angle measurement of modified silicone surfaces after different exposure times to saline solution at 37°C indicated that coated surfaces were stable for over 30 days (Table 1). Adhesion of Staphylococcus epidermidis to the modified silicone surface was investigated as a function of incubation times by scanning electron microscopy (SEM) and the colony counting method. After 4 hr of incubation, the SEM images showed that very few bacteria were attached to the FAS/silicone surface, while large colonies (>40 um) were found on the heparin/OTS/silicone. After 12 hr, the size and number of colonies increased significantly, but FAS/silicone still showed the least amount of bacterial adhesion. Similarly, using the colony count method, at 4 h the pattern of bacterial adhesion on the five different surfaces was found to be FAS/silicone