Comparison of antibacterial properties of commercial bone cements and fillers with a zinc-based glass polyalkenoate cement

Postoperative infection following invasive surgical procedures is a significant cause for concern, particularly in spinal reconstructive surgery. The objective of the study was to compare the antibacterial efficacy of a novel zinc based glass polyalkenoate cement (Zn-GPC) based on 0.04SrO-0.12CaO-0.36ZnO-0.48SiO2 glass, to a number of commercially available bone cements and fillers including Simplex P + Tobramycin (STob), Spineplex (Spine) and Novabone Putty (NPut). The agar diffusion test was performed on each material against E. coli, S. epidermidis, P. aeruginosa and S. Aureus. STob was found to produce large inhibition zones in each of the bacteria tested and was statistically significantly higher than any other material. The experimental Zn-GPC (BTSC) was found to exhibit antibacterial properties in both E. coli and S. epidermidis. Neither Spine nor NPut showed any inhibitory effect in any of the bacteria tested. A study was also performed to determine the effect of antibiotic release from STob and the Zn-GPC (BTob) containing the antibiotic tobramycin (Tob). Antibacterial efficacy was found to increase with respect to maturation with BTob, whereas STob was found to decrease significantly over the time period 0 – 14 days. The final objective was to investigate any change in agar composition during the agar-diffusion test. Little change was observed for STob as antibiotic release cannot be determined using EDX. There was however an increase in Zn levels when analysing BTSC which suggests that Zn is playing a role in the antimicrobial nature of the Zn-GPC. No significant changes were observed for Spine or NPut.