bacterial meningitis
inflammation of the meninges, which form a protective covering for the brain and spinal cord, caused by bacterial infection, most commonly Neisseria meningitidis (the meningococcus), Haemophilus influenzae, or Streptococcus pneumoniae (the pneumococcus). Meningococcal meningitis is highly contagious because the bacteria are present in the throat as well as the cerebrospinal fluid. Common symptoms of bacterial meningitis, which can result in severe morbidity or mortality, include fever, headache, nausea, weakness, and confusion. See also meningitis; tuberculous meningitis.