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SOURCE

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Source: Elshaboury RH, Ahiskali AS, Holt JS, Rotschafer JC. Central nervous system infections. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146071082. Accessed May 1, 2017.

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CONDITION/DISORDER SYNONYMS

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  • Spinal meningitis.

  • Central nervous system (CNS) infection.

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DEFINITION

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  • Infections within the CNS resulting from.

    • Hematogenous spread from primary infection site.

    • Seeding from parameningeal focus.

    • Reactivation from latent site.

    • Trauma.

    • Congenital defects in CNS

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ETIOLOGY

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  • Most common causes: Streptococcus pneumoniae, group B Streptococcus, Neisseria meningitidis, Haemophilus influenza, and Listeria monocytogenes

  • Availability of pneumococcal and H. influenzae vaccines has resulted in decreased incidence.

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PATHOPHYSIOLOGY

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  • Critical first step: nasopharyngeal colonization of host by bacterial pathogen.

    • Bacteria first attach themselves to nasopharyngeal epithelial cells, then are phagocytized into host’s bloodstream.

    • CNS bacterial pathogens have extensive polysaccharide capsule resistant to neutrophil phagocytosis and complement opsonization.

  • Neurologic sequelae of meningitis occur due to activation of host inflammatory pathways.

    • Bacterial cell wall components released, causing capillary endothelial cells and CNS macrophages to release cytokines.

    • Blood-brain barrier altered by proteolytic products and toxic oxygen radicals.

    • Coagulation cascade activated by platelet-activating factor.

    • Vasodilation stimulated by arachidonic acid metabolites.

  • Lead to.

    • Cerebral edema.

    • Elevated intracranial pressure.

    • Cerebrospinal fluid (CSF) pleocytosis.

    • Decreased cerebral blood flow.

    • Cerebral ischemia.

    • Death.

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EPIDEMIOLOGY

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  • Between 2003 and 2007, approximately 4100 cases of acute community-acquired bacterial meningitis, excluding epidemics, occurred annually in the United States, resulting in about 500 deaths.

  • Neurologic sequelae frequently seen include.

    • Seizures.

    • Sensorineural hearing loss.

    • Hydrocephalus.

  • Risk for development of sequelae depends on infecting organism; highest risk associated with pneumococcal meningitis.

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PREVENTION AND SCREENING

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  • Vaccines available for certain types of meningitis described in Treatment: Special Considerations section.

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RISK FACTORS

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  • Passive and active exposure to cigarette smoke.

  • Presence of cochlear implant that includes positioner.

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CLINICAL PRESENTATION

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  • Changes in CSF can be used as diagnostic markers of infection (Table 1).

  • Varies with age.

    • Clinical picture more atypical and less pronounced in younger patients.

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Table Graphic Jump Location
TABLE 1.aMean Values of Components of Normal and Abnormal Cerebrospinal Fluid

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