Meningitis by definition is inflammation of the meninges, the three-layered protective membrane that surrounds the central nervous system. The meninges are made up of the Dura mater, the Arachnoid mater and the innermost Pia mater. It is of the utmost importance to determine whether bacteria, viruses, fungi, toxins or parasites have caused the inflammation and to treat the microorganism quickly and efficiently to provide the best prognosis. It is of utmost importance to determine the cause of the inflammation (e.g. bacteria, viruses, fungi, toxins). While viral or aseptic meningitis requires only supportive treatment, bacterial meningitis is one of the ten most common causes of death from infectious diseases killing approximately 135,000 people per year (Waghdhare, Kalantri, Joshi, & Kalantri, 2010). Pathophysiology To infect the meninges, pathogens must cross the blood-brain barrier. According to Myers, director of infection control at Scripps Mercy Hospital (2000), pathogens enter through an open wound, surgical incision, or mucous membrane. Systemic infections can also cause meningitis (Huether & McCance, 2012) with typical invasion occurring through the middle ear or during respiratory tract infections (Myers, 2000). The bacteria escape the body's immune defenses with their capsule; viruses hide inside the body's cells and invade the cerebrospinal fluid through the cerebral capillary system (Myers, 2000). Once inside, pathogens cause inflammation of the blood vessels, infarctions (necrosis due to obstructed blood flow), edema, hydrocephalus caused by arachnoid obstruction of the villi (site that reabsorbs cerebrospinal fluid) (Huether & McCance, 2012) and decreased cerebral blood flow (Myers 2000). According to Huether and McCance, authors of Understandi...... half of the article...... mDugdale, D., Jatin, V., & Zieve, D. (2012, 10 06). Kernig's sign of meningitis. Retrieved from http://www.nlm.nih.gov/medlineplus/ency/imagepages/19077.htmHuether, S., & McCance, K. (2012). Understanding the pathophysiology. (5th ed.). St. Louis, MO: Elsevier Mosby.Nudelman, Y., & Tunkel, A. R. (2009). Bacterial meningitis. Drugs, 69(18), 2577-2596. doi:http://dx.doi.org/10.2165/11530590-000000000-00000Van, d. B., Brouwer, M. C., Thwaites, G. E., & Tunkel, A. R. (2012). Advances in the treatment of bacterial meningitis. La Lancetta,380(9854), 1693-702. doi: http://dx.doi.org/10.1016/S0140-6736(12)61186-6Waghdhare, S., Kalantri, A., Joshi, R., & Kalantri, S. (2010). Accuracy of physical signs for detecting meningitis: a hospital-based diagnostic accuracy study. Clinical Neurology and Neurosurgery, 112(9), 752-7. doi: http://dx.doi.org/10.1016/j.clineuro.2010.06.003