Introduction

The term “meningitis” refers to inflammation of the leptomeninges covering the brain. Bacterial infection of the meninges usually produces a suppurative process or “purulent meningitis.” However, it is probably more correct in the newborn infant to consider the condition as bacterial meningoencephalitis, since it is common to have involvement of the cerebral hemispheres as well as involvement of the meninges.

From the clinician's perspective it has been traditional to think of neonatal sepsis (septicemia) and meningitis together, because the clinical manifestations may be indistinguishable. For many years, the proportion of cases of neonatal sepsis that also had documented meningitis was considered to be one-quarter to one-third. For instance, in 1986 it was estimated that one case of neonatal meningitis occurs for every four cases of sepsis. Indeed, this was my personal experience in Vermont between 1975 and 1980, when 12 of 41 cases (29%) with neonatal sepsis in the first week after birth had associated meningitis. However, in recent years the proportion of cases seems to be decreasing to as low as 5%. This may be less true in other countries, with 32 of 229 (14%) noted in Israel, and 107 of 577 (18.5%) in Panama.

Incidence

The incidence of neonatal bacterial meningitis will vary from one center to the next, but national studies have shown the incidence to be quite similar (Table 16.1).