<i>Staphylococcus aureus</i> exhibits spatiotemporal heterogeneity in Sae activity during kidney abscess development

Infections with <i>Staphylococcus aureus</i> pose a serious public health threat due to high levels of antibiotic resistance and limited efficacy of alternative therapeutics. There has been a great deal of interest in developing novel therapeutics that target virulence factors essential during infection. However, it remains largely unknown if these factors are required at specific stages of the infection, and whether all bacterial cells or a limited subset express them. Here, we sought to examine virulence factor expression using fluorescent reporter strains that would indicate activity of two master regulators of virulence in <i>S. aureus</i>, Agr and Sae. While Agr appeared inactive during kidney abscess development, the Sae system exhibited heterogeneity, increased expression at later stages, and was required for abscess progression. These results provide critical information for the development of virulence factor-targeting strategies for kidney abscess treatment.