Proteomic analysis of the proteins released from Staphylococcus aureus following exposure to Ag(I)

The silver ion (Ag(I)) has well established antimicrobial properties and is widely used in a variety of anti-bacterial ointments and plasters for the control of wound infections. Wounds are frequently colonised by the bacterium Staphylococcus aureus and the aim of the work presented here was to establish how S. aureus responded following exposure to Ag(I). Exposure of S. aureus to Ag(I) resulted in the release of a range of proteins from cells. Analysis of proteins released revealed a number of proteins associated with the stress response (e.g. alkaline shock protein, methionine sulfoxide reductase), virulence (e.g. signal transduction protein) and metabolism (e.g. lipase, acetate kinase, phosphoglycerate mutase). The release of toxins (e.g. α-hemolysin, bifunctional autolysin, leucocidin F) was decreased. These results indicated that, while silver is a potent antimicrobial agent, exposure of S. aureus to this metal results in the release of a variety of proteins from the cell. Many of the proteins showing increased release were antigenic and would have the potential to induce an inflammatory response at the site of infection and thus delay healing.