5 Questions
What is the primary function of the polysaccharide capsule in Neisseria meningitidis?
Increasing the virulence of the bacterium
What is the primary reason why serotype B is not included in the vaccines?
It is not immunogenic in humans
How many serologic groups are Neisseria meningitidis divided into based on the antigenicity of their capsular polysaccharides?
At least 13
What is the leading cause of epidemic meningitis worldwide?
Serotype A
Which of the following serotypes is responsible for most cases of disease in the United States?
Serotype B
Study Notes
Neisseriae Characteristics
- Neisseriae are gram-negative cocci resembling paired kidney beans.
Neisseria Meningitidis (Meningococcus)
- Has a prominent polysaccharide capsule that enhances virulence by antiphagocytic action.
- The capsule is the immunogen in the vaccine, inducing protective antibodies.
Meningococcal Serologic Groups
- Divided into at least 13 serologic groups based on the antigenicity of their capsular polysaccharides.
Common Serotypes Causing Meningitis and Meningococcemia
- Five serotypes cause most cases: A, B, C, Y, and W-135.
Serotype Distribution
- Serotype A is the leading cause of epidemic meningitis worldwide.
- Serotype B accounts for most disease in the United States.
- Serotype B polysaccharide is not immunogenic in humans, excluded from vaccines.
Learn about Neisseria meningitidis, a gram-negative cocci with a polysaccharide capsule that enhances virulence and is used in vaccine development. Understand the different serologic groups and serotypes that cause meningitis and meningococcemia.
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