meningitis: Bacterial meningitis

A variety of organisms can cause bacterial meningitis, a serious form that can be fatal, especially in children. Symptoms include high fever, headache, chills, vomiting, stiff neck or back, and confusion, sometimes accompanied by a purplish rash. Serious cases can quickly lead to delirium, coma, or convulsions. It is spread by oral or nasal secretions.

The leading cause of bacterial meningitis is the ill-named bacterium Haemophilus influenzae b (Hib), originally thought to be an influenza virus. It commonly affects infants and children. The second most common bacterial cause of meningitis is Neisseria meningitidis (meningococcus). Meningococcal meningitis affects people of all ages and tends to occur in epidemics, especially among those who live in crowded conditions. It is hyperendemic in Africa just south of the Sahara, from Senegal and Guinea east to Eritrea and Ethiopia, and epidemics occur periodically there during the dry season. An outbreak in the slums of Brazil in 1974–75 killed 11,000 people and left over 75,000 with permanent neurological complications. In 1996–97, an epidemic centered in the Sahel region of W Africa killed 25,000. In the United States it is seen most often in children and teens.

Streptococcus pneumoniae, also referred to as pneumococcus, is another cause of serious meningitis cases. It is the most common cause of meningitis in adults. It often accompanies pneumococcus infections in other parts of the body, such as the ear or sinuses. Other bacterial causes of meningitis include group B streptococcus, tuberculosis, leptospirosis, and Lyme disease.

Bacterial meningitis calls for emergency medical care and the administration of antibiotics. Close contacts of patients with bacterial meningitis may receive prophylactic antibiotics, such as rifampin. Definitive diagnosis can be made by laboratory tests of cerebrospinal fluid obtained by a lumbar puncture (spinal tap). Twenty to thirty percent of children who survive bacterial meningitis sustain permanent neurological damage such as deafness, mental retardation, or convulsions. Since the late 1980s, routine vaccination of young children against Hib has virtually eliminated Hib disease in the United States. Routine vaccination against meningococcal meningitis is recommended for pre-adolescents, and vaccination is also recommended for persons in the military or traveling to parts of Africa where the disease is endemic. The meningococcal vaccine does not provide protection against all meningococcus strains; separate vaccines have been developed against serogroup B meningococcus. Development of an inexpensive meningococcal vaccine for the strain most common in Africa's meningitis belt, which stretches from Senegal and Guinea in the west to Ethiopia in the east, led beginning in 2010 to a mass vaccination drive in the region under the sponsorship of the World Health Organization (WHO) and the Program for Appropriate Technology in Health (PATH).

Sections in this article:

• Introduction
• Fungal meningitis
• Bacterial meningitis
• Viral meningitis

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