In recent years, investigators have made significant advances in understanding the pathogenesis of bacterial meningitis, particularly with regard to understanding the cascade of biologic events that cause excessive inflammation within the central nervous system (CNS). Nevertheless, the most important event in the field of bacterial meningitis in the past decade is the dramatic decline in the incidence of Haemophilus influenzae meningitis in children as a result of the widespread use of the conjugated H. influenzae type b vaccine. Currently, the most important clinical challenge in this field is the emergence of the drug-resistant Streptococcus pneumoniae. This problem has significantly complicated initial management of patients with suspected bacterial meningitis. Preliminary data show promise with new conjugated S. pneumoniae vaccines.