Usefulness of SBA-15 mesoporous ceramics as a delivery system for vancomycin, rifampicin and linezolid: a preliminary report

Bone infections are a challenge for modern medicine. The most common pathogen is Staphylococcus aureus, which usually develops a biofilm inside the infected bone. Local release of antibiotics within the infected tissue may diminish this problem because high concentrations of the antibiotic would be delivered to the required place. This study was carried out to evaluate silica-based mesoporous material SBA-15 as a delivery system for three antibiotics with activity against S. aureus, namely vancomycin, rifampicin and linezolid, alone or in combination. SBA-15 disks were loaded with antibiotics by adsorption using a 1000 mg/L solution. Measurements of biological activity were carried out by bioassay tests, and antibiotic release was monitored by high-performance liquid chromatography (HPLC). In all cases, the ceramic disks released most of the antibiotics at the initial stage of the experiments, with concentrations above the susceptibility breakpoints. The most active antibiotic was rifampicin, with an active concentration of 96.14 mg/L at 24 h, followed by linezolid (7.2 mg/L) and vancomycin (5.5 mg/L). In the HPLC measurements, the antibiotic that showed the best release was linezolid, followed by vancomycin; rifampicin alone could not be measured by HPLC with precision. Taking into account all these results, the antibiotic that remains most active after loading and release is vancomycin (77.46%), followed by linezolid (24%). The results presented here demonstrate the efficacy of SBA-15 bioceramics for local release of antibiotics, which could be of interest in the context of bone infection.