Streptococcus pneumoniae and autoimmunity

The genus Streptococcus includes 49 species, 35 of which have been identified as a cause of infections in humans. Species of Streptococcus are divided into groups based on the antigenic structure of the cell wall alongside polysaccharides, which is known as the Lancefield antigen classification. Unlike Group A Streptococcus; Streptococcus pneumoniae does not yet have sufficient evidence as being a causative agent of autoimmune disease. However, cases in which autoimmune diseases are triggered or exacerbated by pneumococcal infection do exist. In addition, several autoimmune diseases were found to predispose to pneumococcal infection.