Staphylococcal biofilm growth on smooth and porous titanium coatings for biomedical applications

Abstract

Implant-related infections are a serious complication in prosthetic surgery, substantially jeopardizing implant fixation. As porous coatings for improved osseointegration typically present an increased surface roughness, their resulting large surface area (sometimes increasing with over 700% compared to an ideal plane) renders the implant extremely susceptible to bacterial colonization and subsequent biofilm formation. Therefore, there is particular interest in orthopaedic implantology to engineer surfaces that combine both the ability to improve osseointegration and at the same time reduce the infection risk. As part of this orthopaedic coating development, the interest of in vitro studies on the interaction between implant surfaces and bacteria/biofilms is growing. In this study, the in vitro staphylococcal adhesion and biofilm formation on newly developed porous pure Ti coatings with 50% porosity and pore sizes up to 50 μm is compared to various dense and porous Ti or Ti-6Al-4V reference surfaces. Multiple linear regression analysis indicates that surface roughness and hydrophobicity are the main determinants for bacterial adherence. Accordingly, the novel coatings display a significant reduction of up to five times less bacterial surface colonization when compared to a commercial state-of-the-art vacuum plasma sprayed coating. However, the results also show that a further expansion of the porosity with over 15% and/or the pore size up to 150 μm is correlated to a significant increase in the roughness parameters resulting in an ascent of bacterial attachment. Chemically modifying the Ti surface in order to improve its hydrophilicity, while preserving the average roughness, is found to strongly decrease bacteria quantities, indicating the importance of surface functionalization to reduce the infection risk of porous coatings.

Antimicrobial technology in orthopedic and spinal implants

“…Singh et al [68] demonstrated that modifying surface roughness (Figures 7 [69] and 8) of a material at the nanoscale level could provide antibacterial properties. Surface characteristic modification has been shown to interfere with osseointegration of the implants, challenging its clinical application [70] . Other studies have shown that certain pathogens are able to adhere, proliferate, and form biofilms more readily on rough surfaces.…”

Role of nanostructured gold surfaces on monocyte activation and Staphylococcus epidermidis biofilm formation

“…Hydrophobic bacteria, such as S. epidermidis, are known to detach more easily and form less biofilm on a hydrophilic surface. [27][28][29] We therefore suggest that increased hydrophilicity, induced by nanotopography, is a factor contributing to the lower amounts of live bacteria seen on the nanostructured surfaces in our experiments. Moreover, a small decrease in live bacteria was found when increasing the density of nanoparticles from 17% to 28%.…”

Bacterial adhesion to biological versus polymer prosthetic materials used in abdominal wall defect repair: do these meshes show any differences in vitro?

“…Many factors will affect bacterial adhesion to a prosthetic surface such as the material's chemical composition, electric charge, hydrophobicity, and surface roughness [5], among others. Multifilament materials [5] and, surface roughness especially, determine microbial adhesion properties such that surface irregularities will favour the adhesion and deposition of biofilms [6] while smooth surfaces will be less susceptible to microbial adhesion [7]. The porosity of the biomaterial surface also conditions its bioreceptivity [8].…”