502A displays increased virulence in a murine model of acute pneumonia.

<p>A) <i>S. aureus</i> USA300 and 502A were infected intranasally (10⁸ cfu) for 20 h in C57Bl/6J mice and mortality assessed (n = 5). WT C57Bl/6J mice were infected with 10⁷ cfu of each strain for 20 h. B) BALF and lung homogenate were assessed for bacterial numbers. C) Total protein content in BALF (n = 8). D) Cells in BALF were stained with fluorescent antibodies and analyzed by flow cytometry. E) Cytokines were measure by ELISA from BALF. Data are from at least two independent experiments. Each point represents a mouse. Lines display median values. ***P<0.001, **P<0.01 and *P<0.05, compared to WT infected controls.