In vitro antibacterial efficacy of tetracycline hydrochloride adsorbed onto Bio-Oss bone graft

Local delivery of antibiotics may provide the advantage of reducing the potential side effects associated with their systemic administration. This study assessed, in vitro, the antimicrobial efficacy of tetracycline hydrochloride (TCH) adsorbed onto Bio-Oss bone grafts against a range of pathogenic bacteria. Various levels of TCH were adsorbed onto Bio-Oss granules by immersing in TCH aqueous solutions of different initial concentrations for 48 h at room temperature. TCH release was assessed in phosphate buffered saline at 37 degrees C, and its antimicrobial efficacy, up to 96 h, was tested against two Gram-negative bacteria associated with periodontal diseases: Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans, and Porphyromonas gingivalis, and one Gram-positive bacterium associated with soft-tissue and bone infections: Staphylococcus aureus. The range of TCH concentrations studied was also assessed for cytotoxicity against osteoblast-like human osteosarcoma cell lines. The amount of TCH adsorbed and released from Bio-Oss was concentration dependent. All TCH adsorbed Bio-Oss resulted in a reduction of A. actinomycetemcomitans, P. gingivalis, and S. aureus and higher concentrations were generally more effective in reducing or eliminating bacterial growth. The proliferation of HOS cells was not substantially reduced except for the maximum concentration of TCH. In addition to its osteoconductive role, TCH adsorbed Bio-Oss could also be functional in negating systemically antibiotic prophylactic treatment in the prevention of implant or biomaterial related infections.