Teasing out the mechanisms of biofilm formation for the treatment of S. aureus infections on indwelling devices: the role of the surface protein SdrC

Antibiotic resistance has become a great challenge in the healthcare setting. In particular antibiotic resistant strains of Staphylococcus aureus pose further challenges. Methicillin resistant S. aureus (MRSA) is widespread in healthcare facilities and in the wider community and multi-drug resistant strains have been identified. S. aureus is normally present on the surface of the skin where it causes no harm. However, it can easily colonize open wounds causing infection. Systemic infections can result from these wound infections leading to severe problems such as sepsis and infective endocarditis. Infection after surgical implantation of devices, such as joint replacements, can result in the formation of biofilms coating the devices that are difficult to treat. Biofilms are an accumulation of bacteria on a surface which often persist as most antibiotics do not easily penetrate them. In biofilms, bacteria interact directly with the foreign surface, with host proteins coating the surface and can also accumulate through interactions directly with each other.

Thus, there are multiple mechanisms involved in biofilm formation. It is important to fully understand all the mechanisms of biofilm formation in order to be able to disrupt their formation and persistence. In our recent paper, we have characterized the direct binding interaction (cell-cell adhesion) through the S. aureus surface protein, serine-aspartate repeat protein C (SdrC). Our study also reveals the mechanism of interaction between SdrC and inert surfaces. Furthermore, we have demonstrated how a small peptide can be used to block these interactions preventing biofilm formation suggesting a possible approach that could be used to treat SdrC dependent S. aureus biofilms. This study is the result of a multi-disciplinary collaboration across research institutes in Ireland and Belgium with Dr. Brennan (RCSI) contributing to the molecular modelling, Prof. Joan Geoghegan, Prof. Timothy Foster and Leanne Hayes (Trinity College Dublin) leading the molecular biology and microbiological functional studies and researchers from University Catholique de Louvain characterizing the interactions quantitatively using atomic force microscopy.

Marian Brennan

More details can be found in “Molecular interactions and inhibition of the staphylococcal biofilm-forming protein SdrC”.