Patients with Staphylococcus aureus colonization of an intravascular catheter but without demonstrated bacteremia within 24 h after intravascular catheter removal had a 24% (12 of 49 patients) chance of subsequent S. aureus bacteremia if they did not receive immediate antistaphylococcal antibiotics. Treatment within 24 h after intravascular catheter removal led to a 83% reduction in the incidence of subsequent bacteremia.