Graziella Pavon-Djavid

Modulation of Staphylococcus aureus adhesion by biofunctional copolymers derived from polystyrene

Abstract Biomaterials-centered infections are serious complications associated with the use of implants. The infection risk of biomaterials varies between different materials and is determined by the chemical composition of materials, the host proteins and the type of bacteria. In this study we measured the initial adhesion of Staphylococcus aureus onto polystyrene derivatives containing carboxylate and sulfonate groups. Five polymers were synthesized and characterized. We studied the role of the host protein fibronectin in promoting adhesion of Staphylococcus aureus. Fibronectin adsorption was comparable on all the tested polymers (pKd=7.2±0.2) whereas bacterial adhesion was dependent on surfaces chemical compositions. Polymers substituted with sulfonate groups showed the most important inhibition of initial bacterial adhesion.

Inhibition de l’adhérence de Staphylococcus epidermidis sur des surfaces en titane par des polymères hydrosolubles bioactifs comportant des fonctions sulfonate, phosphate ou carboxylate

Implanted prostheses are sometimes subject to bacterial infections, which can threat their benefit rule on a long-term basis. Various methods are studied to fight against these infections. Among them, the grafting of bioactive polymers onto the prosthesis surface shows up as a promising way to the problem of infections. This work presents the influence of various water-soluble bioactive polymers on the inhibition of the Staphylococcus epidermidis adhesion on the titanium samples surfaces initially preadsorbed with various proteins. Whatever the studied protein is, it is shown that the bioactive polymer containing sulfonate functions generates an inhibition of the adhesion of Staphylococcus epidermidis. For a plasma preadsorption, the inhibition rate rises up to 68% when the concentration of sulfonate function is 2.5μmol/L. Titanium surfaces grafted with the bioactive polymer were also tested. We find an inhibitive activity of the adhesion close to that of the previous case. These preliminary results can point up a clinical interest in the fight against the medical devices infection, because they highlight a clear local effect of S. epidermidis adhesion inhibition. Copolymers containing other functional groups (phosphate or carboxylate) were dissolved in a bacterial suspension to monitor the influence of the composition on the adhesion inhibition. Their inhibition rates are not significantly lower than those of pNaSS homopolymers, as much as the sulfonate function proportion remains higher than 50%. Thus, the sulfonate function is the main responsible for the inhibition of the S. epidermidis adhesion.

289 Inhibition de l’adhérence bactérienne sur le ciment

Introduction Plusieurs strategies existent ou sont en cours d’etude pour la prevention des infections de protheses articulaires. L’impregnation d’antibiotiques sur les surfaces des implants et du ciment a ete proposee, mais plus recemment l’adjonction de polymeres bioactifs modifiant les capacites d’adherence bacterienne semble une solution interessante. L’etude de l’inhibition de l’adherence bacterienne sur le ciment avec polymeres est presentee ici. Materiel et Methode Il s’agit d’une etude in vitro realisee a partir d’echantillons de ciment a base de polymethacrylate de methyle (PMMA). La souche bacterienne utilisee est un Staphylococcus aureus resistant a la Methicilline. Du polymere bioactif porteur de groupements sulfonates a ete ajoute au polymere de PMMA a differentes concentrations. Pour chaque concentration de polymere, des mesures d’adherence bacterienne ont ete realisees sur les echantillons de PMMA avec une concentration identique d’albumine et de fibrinogene et apres une culture overnight d’une suspension de Staphylococcus aureus. Lors de chaque manipulation, des echantillons « temoins » avec du PMMA sans polymere etaient egalement testes pour pouvoir comparer les modifications d’adherence du Staphylococcus aureus au ciment. Le nombre d’unites formant colonies (ufc) presentes sur les echantillons de ciment etait ensuite calcule et rapporte au nombre d’ufc incubees. Resultats Pour les differentes concentrations de polymere ajoute au PMMA, l’adherence du Staphylococcus aureus sur la surface des echantillons de ciment etait plus faible en presence de polymere. La concentration la plus faible de polymere permettant une diminution de l’adherence bacterienne a ete recherchee. Discussion L’inhibition de l’adherence bacterienne par la modification de la surface des implants ou du ciment semble une voie interessante dans la lutte contre les infections sur protheses. Des tests biomecaniques sont cependant necessaires pour verifier l’absence de modification du comportement mecanique du ciment. Conclusion L’adjonction de polymeres bioactifs au ciment permet d’observer une diminution de l’adherence bacterienne in vitro. D’autres etudes in vitro et in vivo sont en cours.