Infections caused by Staphylococcus aureus are the primary bacterial threat to the health of New Zealanders. People who have asymptomatic S. aureus colonisation of their noses are at increased risk of developing disease; the highest risk of life-threatening disease occurs among people who require renal dialysis. The role that the numerous other types of bacteria (the nasal microbiome) play in the development of S. aureus nasal colonisation is not known. We propose to compare the nasal microbiomes of healthy adults and renal dialysis patients who are persistently or never colonised with S. aureus. We also propose to determine the changes in the nasal microbiome that occur following treatment to cure S. aureus nasal colonisation among renal dialysis patients. The results of this research will be used to identify strategies, such as the potential to use non-harmful competing bacteria, to prevent nasal S. aureus colonisation and, therefore, S. aureus disease.