Secondary Bacterial Pneumonia by Staphylococcus aureus Following Influenza A Infection Is SaeR/S Dependent

Abstract

<p id="d8907577e176"> <i>Staphylococcus aureus</i> is a predominant cause of fatal pneumonia following influenza A virus (IAV) infection. Herein we investigate the influence of antecedent IAV infection on <i>S. aureus</i> virulence gene expression. Using a murine model, comparing the USA300 and USA300Δ <i>saeR/S</i> strains, we demonstrate that <i>S. aureus</i> pathogenesis following IAV infection is SaeR/S dependent. Furthermore, we show that IAV modulates the lung environment to rapidly up-regulate <i>S. aureus</i> virulence factors containing the SaeR-binding domain. Data demonstrate that the pathogen response to IAV infection impacts host outcome and provides evidence that the ability of <i>S. aureus</i> to sense and respond to the lung environment determines severity of pneumonia. </p>