Antibody against the R domain of coagulase protects against S. aureus bloodstream infection. Purified mAbs 5D5, 3B3, or IgG1 isotype control were injected at a concentration of 5 mg kg⁻¹ body weight into the peritoneal cavity of naive BALB/c mice. Animal cohorts (n = 10 per experiment) were challenged by intravenous injection with S. aureus Newman (A), the Δvwb variant of Newman (B), MRSA USA300 (C), MRSA N315 (D), MRSA252 (E), or WIS (F), and survival was monitored over 10 d. Data are representative of two independent analyses; statistical significance was assessed with the log-rank test.