Microbial adhesion to ionogenic PHEMA, PU and PP implants

This study concentrates on adhesion of microorganisms to polymeric biomaterials implanted in the urinary tract. A number of extensively used polymeric biomaterials (i.e., poly(hydroxyethyl-methacrylate) and its copolymers with a series of acrylic monomers--acrylic acid and dimethylaminoethyl methacrylate--polyetherurethane and polypropylene (PP)) was prepared by using suitable polymerization methods. Their surface structures were characterized by wettability and surface free energy measurements, scanning electron microscopy, electron spectroscopy for chemical analysis, and attenuated total reflection Fourier transform infrared spectroscopy techniques. It was found that these surfaces have different surface free energies in the range of 26.9-63.0 erg cm-2 with different charge and charge densities. The adherence of two strains of Escherichia coli (non-pathogen and pathogen) isolated from indigenous flora of trachea and pathogen flora of urethral surfaces, and uropathogenic Candida albicans to the polymeric surfaces was studied in vitro by means of microscopic techniques. The hydrophobicity of cell surfaces was determined by using two methods including adhesion to hydrocarbons and contact angle measurements. The uropathogenic E. coli and C. albicans were found to be relatively hydrophobic with a similar surface free energy, approximately 40 erg cm-2, when compared with normal E. coli strain which has 61 erg cm-2 free energy. The uropathogenic strains were poorly adherent to hydrophilic polymer surfaces while showing excellent adherence on hydrophobic PP surfaces. However, a relatively hydrophilic, nonpathogenic E. coli strain showed the opposite adhesion behaviour to the same surfaces.