1, 2 Despite the advances in the design of, for example, the total artificial heart, mammary prostheses, different orthopaedic implants and voice prostheses, there is at present no solution to the problem of infection other than removing the implant. Infection is still the most common cause of biomaterial implant failure in modern medicine. These results suggest that positively charged biomaterial surfaces exert an antimicrobial effect on adhering Gram-negative bacteria, but not on Gram-positive ones. On the negatively charged surfaces, despite a slower initial adhesion, surface growth of the adhering bacteria was exponential for both Gram-positive and Gram-negative strains. All bacteria adhered most rapidly to the positively charged surface, but there was no subsequent surface growth of the Gram-negative strains. Adhering bacteria were allowed to multiply by perfusing the flow chamber with growth medium. Initial adhesion of Staphylococcus aureus ATCC 12600, Staphylococcus epidermidis HBH 2 102, Escherichia coli O2K2 and Pseudomonas aeruginosa AK1 to these surfaces was measured in a parallel plate flow chamber in phosphate-buffered saline.

In this study, the antimicrobial effects on adhering bacteria of a positively charged poly(methacrylate) surface (ξ potential +12 mV) were compared with those of negatively charged poly(methyl methacrylate) (–12 mV) and a highly negatively charged poly(methacrylate) (–18 mV) surface. The infection of biomaterials is determined by an interplay of adhesion and surface growth of the infecting organisms.

Negative 48