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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]
13 serotypes of meningococci have been isolated based on their polysacchride capsule out of which five of them causes clinically severe diseases. They are also classified according to outer membrane protein.
- Meningococci are classified by using serologic methods based on the structure of the polysaccharide capsule.
- 13 Serotypes are described based on capsular polysaccharide: A, B, C, D, X, Y, Z, E, W-135, H, I, K, and L.
- Serogroup A usually with epidemics in less developed nations and an attack rate of as high as 500 cases per 100,000 population.
- Serogroup B usually in developed nations with attack rate of 50-100 cases per 100,000 population.
- Serogroup C usually in both developed and less developed populations and an attack rate of up to 500 per 100,000 population.
- Some strains, often those found to cause asymptomatic nasopharyngeal carriage, are not groupable and do not have a capsule.
- Almost all invasive disease is caused by one of five serogroups: A, B, C, Y, and W-135.
- The relative importance of each serogroup depends on geographic location, as well as other factors, such as age. For instance, serogroup A is a major cause of disease in sub-Saharan Africa but is rarely isolated in the United States.
- Meningococci are further classified on the basis of certain outer membrane proteins. Molecular subtyping using specialized laboratory techniques (e.g., pulsed-field gel electrophoresis) can provide useful epidemiologic information.[1]
Classification of Clinical Presentations[edit | edit source]
- They present with a wide range of clinical conditions from transient bacteremia to rapidly progressing septicemia.
- Most of them develop meningitis as meningococci invade the meninges.
- Meningococcal infections are classified into four different clinical groups based on the following conditions:
- Presence or absence of signs of septic shock.
- Presence or absence of clinical symptoms and laboratory signs of distinct meningitis.
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| Clinical group
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Characteristic feature
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Case fatality
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| Fulminent meningocccal septicemia
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Persistent and severe septic shock, which lasts for more than 24 hours, associated with minimal pleocytosis or lack of clinical manifestations of meningitis.
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25-55%
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| Distinct meningitis
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Marked pleocytosis or distinct clinical signs of meningitis.
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10-25%
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| Distinct meningitis and persistent septic shock
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Marked pleocytosis or distinct signs of meningitis associated with severe septic shock.
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<5%
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| Mild systemic meningococcal infection
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Mild meningococcemia without signs of meningitis or persistent septic shock.
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0%
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| Table adapted from Handbook of meningococcal disease [2]
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Original source: https://wikidoc.org/Meningococcemia classification
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