Murine Systemic Staphylococcus aureus Infection

TSB medium was inoculated with S. aureus strains from a pre-culture and grown to mid-exponential growth phase (2–3 h). Bacteria were harvested, washed and diluted in sterile PBS. CFU were determined by diluting and plating on TSB plates. Six-week old female C57BL/6 wild-type mice purchased from Harlan Laboratories, C57BL/6 TLR2^−/−43 (link), or C57BL/6 FPR2^−/−50 (link) mice were challenged with 1 × 10⁷ live bacteria in 0.2 ml PBS injected into the tail vein as described recently43 (link). Survival and disease progression was monitored over 14 days. Blood was collected from some mice 6 and 17 h after infection. Cytokine/chemokine levels in blood serum were determined following the manufacturer's instructions with a custom-made Luminex assay including magnetic beads for the measurement of CXCL2 (MIP-2), IL-1β, IL-6 and TNFα (R&D Systems, Minneapolis, MN, USA). The samples were analysed on a Bio-Plex MAGPIX Multiplex Reader (Bio-Rad Laboratories, Munich, Germany) with Bio-Plex Manager MP Software (Bio-Rad) and ELISA (R&D Systems, Minneapolis, MN, USA).