Meningitis is the inflammation of the meninges (the triple layer membrane that covers the brain and spinal cord). The main causative agents are viruses and bacteria.


“S. pneumoniae, H.influenza type b, and N. Meningitiditis are encapsulated organisms that invade the host through the upper airway, surviving dissemination to the bloodstream, and then gain access to the subarachnoid space.” “In direct contiguous spread, organisms gain entry into the cerebrospinal fluid from adjacent infections such as sinusitis, brain abscess, or otitis media. Organisms can also enter directly with penetrating traumatic injury, through congenital defects, or during neurosurgical procedures.”1


“The classic signs and symptoms are fever, neck stiffness, headache, and altered mental status, and are probably present in most cases of bacterial meningitis.”1


“Definitive diagnosis is based on demonstrating bacterial organisms and a corresponding inflammatory response in the CSF (CSF Analysis). Antibiotic therapy should be initiated in the ED as soon as possible for presumptive bacterial meningitis and should not be delayed for neuroimaging for lumbar puncture.”1 A review of CNS infections can be found here



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  1. Loring, K., Tintinalli, J., Chapter 168, “Central Nervous System and Spinal Infections”. Tintinalli’s Emergency Medicine – A Comprehensive Study Guide. J Tintinalli. 7th ed. McGraw-Hill Education, 2010. 


Prepared by Alex Mungham PGY1 FM – University of Ottawa