DefinitionThis section has been translated automatically.
Streptococcus pneumoniae (pneumococcus) is a gram-positive bacterium (turning blue when Gram stained) that belongs to the group of streptococci (chain cocci). However, the chain here consists of only two links. These are diplococci. Streptococcus pneumoniae has no Lancefield group antigens. However, the antigenic structure of the polysaccharide capsule allows a subdivision into 91 serovars. The polysaccharide capsule is the most important pathogenicity factor and has an antiphagocytic effect.
Worldwide, pneumococcal diseases cause the death of about two million people per year.
Risk factors for disease are:
- age (children and the elderly have a significantly higher incidence)
- congenital and acquired immunodeficiencies
- chronic diseases (e.g. alcoholism, chronic heart or lung diseases, splenectomy).
For further information see below. Pneumococcus.
