Evaluation of bacterial adherence of clinical isolates of Staphylococcus sp. using a competitive model: An in vitro approach to the "race for the surface" theory.

OBJECTIVES: Implant-related infection is one of the most devastating complications in orthopaedic surgery. Many surface and/or material modifications have been developed in order to minimise this problem; however, most of the in vitro studies did not evaluate bacterial adhesion in the presence of eukaryotic cells, as stated by the 'race for the surface' theory. Moreover, the adherence of numerous clinical strains with different initial concentrations has not been studied. METHODS: We describe a method for the study of bacterial adherence in the presence of preosteoblastic cells. For this purpose we mixed different concentrations of bacterial cells from collection and clinical strains of staphylococci isolated from implant-related infections with preosteoblastic cells, and analysed the minimal concentration of bacteria able to colonise the surface of the material with image analysis. RESULTS: Our results show that clinical strains adhere to the material surface at lower concentrations than collection strains. A destructive effect of bacteria on preosteoblastic cells was also detected, especially with higher concentrations of bacteria. CONCLUSIONS: The method described herein can be used to evaluate the effect of surface modifications on bacterial adherence more accurately than conventional monoculture studies. Clinical strains behave differently than collection strains with respect to bacterial adherence.Cite this article: M. Martinez-Perez, C. Perez-Jorge, D. Lozano, S. Portal-Nuñez, R. Perez-Tanoira, A. Conde, M. A. Arenas, J. M. Hernandez-Lopez, J. J. de Damborenea, E. Gomez-Barrena, P. Esbrit, J. Esteban. Evaluation of bacterial adherence of clinical isolates of Staphylococcus sp. using a competitive model: An in vitro approach to the "race for the surface" theory. Bone Joint Res 2017;6:315-322. DOI: 10.1302/2046-3758.65.BJR-2016-0226.R2.

Use of anodized titanium alloy as drug carrier: Ibuprofen as model of drug releasing.

The use of osteoarticular implants has improved the quality of life of millions of patients. In this work nanotubular structures tailored made on Ti6Al4V substrates was used as drug delivery system of ibuprofen as a proof of concept. Three different nanotubular films with different sizes and forms (NT, NT+ and NTb) were analysed. Samples were soaked in a solution of 660 mg ibuprofen/20 mL n-pentane. The ibuprofen release in aqueous medium was evaluated by liquid chromatography reversed-phase (RP-HPLC). To calculate the observed constant k, the amount of ibuprofen released was plotted versus the time using linear regression according to the zero-order, first-order, second-order and Higuchi model. The release of ibuprofen was constant and independent of the concentration. The kinetic constant obtained was 0.021 (NT), 0.022 (NT+) and 0.013 (NTb) being the correlation factor of 0.98 (zero-order) where the maximum correlation factor was reached. These results indicate that the delivery process from NT and NT+ is similar and slower that NTb. In all the cases was inside the therapeutically range. These results showed the potential of these modifications in order to develop implants that can carry different molecules of medical importance.