Staphylococcus aureus is a major human pathogen. Nasal colonization by S. aureus is a significant risk factor for severe infections. Staphylococcal phages expand the genetic repertoire by horizontal gene transfer (HGT) and often carry genes benefitting the bacterial host such as resistance and immune evasion factors. Phage-mediated HGT in mainly S. aureus has been studied comprehensively, emphasizing the importance of phage-receptor interactions and anti-viral defence systems. Despite that little is known how and to what degree the natural ecological niche of S. aureus, the human nose, and its microbiome govern prophage induction and phage-mediated HGT.

To investigate this question, we assembled a bacterial collection of more than 290 bacterial isolates from 11 different communities, which we are currently characterising. We probed the ability of nasal commensals (n=150) and selected xenobiotics to modulate S. aureus prophage induction by using a lacZ-based reporter strain. Furthermore, we analysed the genomic viral content of 40 staphylococcal commensals from different nasal communities from the nasal collection and looked for occurrences of intra-communal HGT.

On the one hand we found no evidence for the capacity of nasal commensals or xenobiotics to directly influence S. aureus prophage induction. On the other hand, examining the shared genetic content of predicted staphylococcal prophages we observed indicators for genetic exchange within nasal communities among staphylococci. In further research we will investigate how staphylococci and other nasal commensals drive and participate in HGT leading to the development of countermeasures to prevent dissemination of virulence and resistance genes.