Rapid acquisition of virulence and antibiotic resistance genes by horizontal gene transfer (HGT) influences the transition of Staphylococcus aureus from commensal to a pathogenic bacterium. Bacteriophages are considered the primary mediators of HGT among staphylococci, as this group lacks natural competence and functional conjugation systems. However, little is known about the occurrence of this phenomenon in vivo. The nasal environment may act as a reservoir for the spread of phage-mediated virulence and antibiotic resistance genes in S. aureus. This project aims to elucidate the role of phages in HGT in staphylococci within the nasal environment and how the composition of the nasal microbiome may influence this process.