Background: The functions of synthetic bone graft substitutes include not only structural support to provide bone healing and osseous ingrowth but also the ability to serve as a local antibiotic delivery system to prevent or treat infections of the spine.
Material and methods: The impregnation and antibiotic efficiency of gentamicin and levofloxacin with Healos was investigated in vitro and compared with Healos without an antibiotic additive. These antibiotic-loaded bone graft substitutes were examined without dilution and with 10-fold and 100-fold dilution for activity against spondylodiscitis-causing bacteria on different agar plates using an agar diffusion method.
Results: All hydroxyapatite (HA)/collagen-saturated diluted antibiotics showed elliptical inhibition zones on the corresponding agar plates. For both antibiotics, there was a linear correlation between dilution and area of the inhibition zone.
Conclusion: The analysis showed that the antimicrobial activity of HA/collagen-saturated antibiotics corresponded to the antimicrobial dilutions. These results should be further analyzed using in vivo studies to determine the remaining antibiotic efficiency after implantation of bone graft substitutes.