Introduction

Prosthetic joint infections (PJI) occur infrequently, but due to its increased clinical use represent the most devastating complication with high morbidity and substantial cost. Staphylococcus aureus and coagulase-negative staphylococci are the most common infecting agents associated with PJI. A possible therapeutic approach could be the local antibiotic by fluoride-TiO2 nanostructured anodic layers in order to prevent surface colonisation during the early moments after surgery. Here we describe the first results of this model using two common antibiotics.

Prosthetic joint infections (PJI) occur infrequently, but they represent the most devastating complication with high morbidity and substantial cost. Staphylococcus aureus are the most common infecting agents associated with acute PJI, and also appear in some cases of delayed PJI¹. S. aureus biofilm development can be divided in two stages: adhesion and proliferation². To avoid PJI bacterial adhesion has to be decreased.

Hybrid organo-inorganic sol-gel coatings are proposed as a promising biomaterial improvement³. One of these compounds is a mixture of two organopolisiloxanes: 3-methacryloxypropyltrimethoxysilane (MAPTMS) and tetramethylorthosilicate (TMOS). The aim of this work was to evaluate bacterial adhesion on MAPTMS-TMOS coating compared to titanium parts made by powder metallurgy.

MAPTMS-TMOS sol-gel coating was produced using a molar ratio of 1:2 (MAPTMS:TMOS) and dispersed in ethanol. The sol-gel was deposited by dip-coating on titanium parts made by powder metallurgy followed by a thermal treatment at 120 ºC for 30 minutes⁴. Titanium parts without sol-gel coating were used as control.

S. aureus 15981 strain adherence study was performed using the protocol described by Kinnari et al.⁵ with 90 min incubation. After incubation, the samples were stained with LIVE/DEAD BacLight Bacterial Viability Kit. Proportion of total adhered, live and dead bacteria was calculated and studied by using ImageJ software. The experiments were performed in triplicate.

The statistical data were analyzed by pairwise comparisons using the nonparametric Mann-Whitney test with a level of statistical significance of p<0.05. Values are cited and represented as medians.

S. aureus 15981 adherence was 942-fold lower on MAPTMS-TMOS coating than on uncoated titanium.

According with our results, MAPTMS-TMOS sol-gel coating is a promising antiadherent surface for S. aureus. More studies are necessary in order to evaluate this property with other species and strains.

Bone-regenerative and biocompatible materials are indicated for the regeneration of bone lost in periodontology and maxillofacial surgery. Bio-Oss is a natural bone mineral for bone grafting of bovine origin and the most common used in this kind of interventions¹. Sil-Oss is a new synthetic nanostructured monetite-based material that is reabsorbed at the same time that is replaced by new bone tissue ². Bacterial infection is one of the complications related to this kind of material. Streptococcus oralis is the most associated oral infecting pathogen to oral surgery³ and Staphylococcus aureus is the most common infecting pathogen to maxillofacial non-oral interventions⁴. Here we evaluated bacterial adherence of two of the most common infecting bacteria of this kind of biomaterial: S. oralis and S. aureus, on Bio-Oss and Sil-Oss.

S. oralis ATCC 9811 and S. aureus 15981 strains were used. Bacterial adherence was evaluated using the modified previously described protocol of Kinnari et al.⁵ that was adapted to our biomaterial. The quantification was performed by the drop plate method⁶. The statistical data were analyzed by pairwise comparisons using the nonparametric Mann-Whitney test with a level of statistical significance of p<0.05. Values are cited and represented as medians.

Bacterial adherence decreased significantly on Sil-Oss compared to Bio-Oss. S. oralis ATCC 9811 adherence was between 11 and 13-fold less on Sil-Oss compared to Bio-oss. In the case of S. aureus15981, the adherence was between 4 and 6-fold less on Sil-Oss compared to Bio-Oss.

Sil-Oss nanostructured monetite-based biomaterial could be considered as a promising biomaterial to be used for the regeneration of bone defects since the bacterial adherence on it is lower than on another currently used material.