[Epidemiology of primary bacterial meningitis]

In industrialized countries, the incidence of community-acquired bacterial meningitis is between 5 and 10 cases/10(5) population/year. The highest age-specific attack rates are recorded between 0 and 2 years of age and can reach 100 cases/10(5) population/year or more in some countries. In this range of age, Streptococcus agalactiae, Listeria monocytogenes and Escherichia coli are responsible for meningitis in neonates whereas Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae cause meningitis in children older than 1 month. H. influenzae was the leading cause of bacterial meningitis in children but its incidence has declined since the introduction of routine childhood immunization with conjugate vaccines. N. meningitidis is the leading cause of meningitis in teenagers and young adults, whereas S. pneumoniae is responsible for most of meningitis in the elderly. Prognosis of bacterial meningitis mainly depends on the type of causative organism and on the age of onset. Detailed epidemiologic features of Haemophilus, meningococcal and pneumococcal meningitis are provided.