Nisin F-loaded brushite bone cement prevented the growth of Staphylococcus aureus in vivo

Abstract

To determine if nisin F-loaded self-setting brushite cement could control the growth of Staphylococcus aureus in vivo. Brushite cement was prepared by mixing equimolar concentrations of β-tricalcium phosphate and monocalcium phosphate monohydrate. Nisin F was added at 5·0, 2·5 and 1·0% (w/w) and the cement moulded into cylinders. In vitro antibacterial activity was determined using a delayed agar diffusion assay. Release of nisin F from the cement was determined using BCA protein assays. Based on scanning electron microscopy and X-ray diffraction analysis, nisin F did not cause significant changes in cement structure or chemistry. Cement containing 5·0% (w/w) nisin F yielded the most promising in vitro results. Nisin F-loaded cement was implanted into a subcutaneous pocket on the back of mice and then infected with S. aureus Xen 36. Infection was monitored for 7 days, using an in vivo imaging system. Nisin F prevented S. aureus infection for 7 days and no viable cells were isolated from the implants. Nisin F-loaded brushite cement successfully prevented in vivo growth of S. aureus. Nisin F incorporated into bone cement may be used to control S. aureus infection in vivo.