Project Summary Staphylococcus aureus is a leading cause of human infection worldwide. Investigations into Staphylococcus aureus pathogenesis have focused on mono-species infections and the impact of co-infecting microbes on S. aureus physiology during infection remains understudied but critically important. My recent work has focused on characterizing S. aureus physiology during mono- and co-infection with Pseudomonas aeruginosa using next- generation sequencing techniques. The current application builds logically on this work and is focused on characterizing the interactions between S. aureus and co-infecting microbes within chronic wound infections. The overall goal of this application is two-fold: 1) to define the metabolic interactions that occur between S. aureus and co-infecting microbes during infection (Specific Aim 1); and 2) to expand on these findings to determine the impact of microbe-microbe interactions on S. aureus physiology within human infections (Specific Aim 2). This work is likely to yield important discoveries that will aid in our understanding of the underlying mechanisms of microbe-microbe interactions within chronic polymicrobial infections.