Grant: Master's Award: Canada Graduate Research Scholarships - Master's program

The Staphylococcus aureus bacterium and influenza A virus are two pathogens many of us have encountered at least once. S. aureus can cause many different infections, including skin, lung, and bloodstream infections. Its infection of the bloodstream, called S. aureus bacteremia (SAB), is a major cause for concern due to its estimated case fatality rate of 15-50%. Influenza A virus (IAV) is mainly known for causing mild infections of the respiratory tract during the annual flu season, but the virus can cause occasional pandemics with more severe consequences. Interestingly, these two pathogens are known to work together, since IAV can help S. aureus infect the lungs, which worsens disease symptoms. However, we do not know if IAV infection can increase the risk of S. aureus infection in areas other than the lungs. To investigate this, we analysed data from human SAB cases and found that, concerningly, if a person had an IAV infection before contracting SAB, their risk of death increased by up to 8%. To investigate how prior IAV infection increases the risk of dying from SAB, we will infect mice with both pathogens. This will allow us to measure how both the virus and bacteria grow, understand how the immune system responds to the infections, and see how the organs are impacted. By infecting mice first with IAV, letting them recover, and then infecting with S. aureus, we can see how having a prior virus infection changes the outcome of a later bacterial infection. This research will address a major gap in our understanding of how these two infections might affect one another. This can help us develop better treatments which will improve patient outcomes.