Infections of the Central Nervous System caused by bacteria are a major health problem in all regions of the world and represent a challenge for the attending physician, who needs the close cooperation of the microbiologist and the epidemiologist for a correct individual management, basic for a satisfactory prognosis. On the other hand, the sudden onset of symptoms and a fatal outcome in a few hours, or the permanence of terrible sequelae cause these diseases to have a great social impact, which makes the population demand prevention or control measures to protect them, not existing for many of these entities the possibility of implementing effective primary prevention actions. The incidence of Bacterial Meningoencephalitis (B.E.M.) in Western Europe and the United States is estimated to vary from 5 to 10 cases per 100,000 Hbts. during endemic periods. BACTERIAL MENINGITIS is a group of very severe infections that can put the patient's life in great danger and also leave serious sequelae.