Big problem in day care centers. Usually follows a viral infections that opens the way for the bacteria to get into the blood stream and then into the meninges. Most cases of pneumococcal meningitis occur in children from 1 month to four years. Aerobic, nonmotile, gram negative cocci. Usually strikes children under 2.
Diagnosis requires spinal tap - centrifuge CSF and gram stain.
There are also latex agglutination tests using antibodies to this organism and cultures may be done as well. Usually a mild disease, but bacteria are shed in feces indefinitely. Listeria grow inside phagocytes and proliferate within macrophages. Mainly affects adults who are immunosuppressed, pregnant, or have cancer. Growth in CNS results in a meningitis.