Insights into the Staphylococcus aureus-Host Interface: Global Changes in Host and Pathogen Gene Expression in a Rabbit Skin Infection Model

Staphylococcus aureus is an important cause of human skin and soft tissue infections (SSTIs) globally. Notably, 80% of all SSTIs are caused by S. aureus, of which similar to 63% are abscesses and/or cellulitis. Although progress has been made, our knowledge of the host and pathogen factors that contribute to the pathogenesis of SSTIs is incomplete. To provide a more comprehensive view of this process, we monitored changes in the S. aureus transcriptome and selected host proinflammatory molecules during abscess formation and resolution in a rabbit skin infection model. Within the first 24 h, S. aureus transcripts involved in DNA repair, metabolite transport, and metabolism were up-regulated, suggesting an increase in the machinery encoding molecules involved in replication and cell division. There was also increased expression of genes encoding virulence factors, namely secreted toxins and fibronectin and/or fibrinogen-binding proteins. Of the host genes tested, we found that transcripts encoding IL-8, IL1 beta, oncostatin M-like, CCR1, CXCR1 (IL8RA), CCL4 (MIP-1 beta) and CCL3 (MIP1 alpha)-like proteins were among the most highly up-regulated transcripts during S. aureus abscess formation. Our findings provide additional insight into the pathogenesis of S. aureus SSTIs, including a temporal component of the host response. These results serve as a springboard for future studies directed to better understand how/why mild or moderate SSTIs progress to invasive disease.