Interactions of the Pneumococcus with the Central Nervous System: Postnatal Meningitis Versus Fetal Neurodevelopment

In young children, pneumococcal meningitis epitomizes the paradigm of a destructive innate inflammatory response in the central nervous system: a five-alarm fire. In contrast, cell-free bacterial components reaching the fetal brain from an infected mother signal a quiet, noninflammatory immune response that drives abnormal neurodevelopment, changing brain architecture through neuroproliferation. This review addresses the difference between prenatal and postnatal bacterial-host signaling within the brain.