Meningococcemia classification
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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]
Overview
Classification
- 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]