Primary bloodstream infection with secondary hematogenous spread to CNS Presence of an infectious foci with secondary bloodstream infection and hematogenous spread (e.g., osteomyelitis) Presence of an infectious foci with direct extension into the CNS (e.g., sinus infection) Primary CNS infection resulting from disruptions due to head trauma, neurosurgery, or congenital defects (e.g., myelomeningocele)