Meningitis bacteria. Coloured scanning electron micrograph (SEM) of Neisseria meningitidis bacteria (red) on human epithelium. Neisseria meningitidis is an obligate human parasite that causes meningococcal meningitis, the inflammation of connective tissue membranes lining the brain and spinal cord. Symptoms include headache, fever, stiff neck, vomiting, delirium, sometimes death. Treatment is with antibiotics.