The Antimicrobial Properties of Exogenous Copper in Human Synovial Fluid Against Staphylococcus aureus: An In-Vitro Study
Abstract
We sought to analyse the antimicrobial properties of exogenous copper in human synovial fluid against Staphylococcus aureus. We performed several in-vitro growth and viability assays to determine the capability of multiple S. aureus strains to survive in synovial fluid under different growth conditions. S. aureus UAMS-1 significantly died at 24 hours (p=0.017), and S. aureus USA300 WT survived at 24 hours. We confirmed a high sensitivity to killing with the addition of exogenous copper on both strains at 4 (p=0.011), 12 (p=0.011), and 24 hours (p=0.011). Both WT and CopAZB-deficient USA300 strains significantly died in synovial fluid, evidencing a minimum bactericidal concentration of copper of 50 µM against USA300 WT (p=0.011). Synovial fluid has antimicrobial properties against S. aureus, and the addition of 10µM of copper was highly bactericidal for both strains. Furthermore, we identified the CopAZB proteins as potential targets and the use of low exogenous copper concentrations as possible treatment alternatives against S. aureus.