Illustration of the bacteria Neisseria meningitidis, the agent which causes meningitis. These are non-motile, Gram-negative coccus (spherical) bacteria. Neisseria meningitidis is an obligate human parasite. It causes meningococcal (cerebrospinal) meningitis, the inflammation of connective tissue membranes lining the brain & spinal cord. Symptoms include headache, fever, muscle rigidity, delirium, sometimes death. Treatment with antibiotics.