Antigenic composition of the cell wall of Streptococcus mitis

Abstract

Streptococcus mitis, previously described as a serologically unclassifiable species, has been serologically grouped by the cell wall agglutination method. The three ATCC strains and thirty-three oral strains of Strep. mitis were divided into two serological groups. Group I reacted only with antisera for Group N and consisted of ATCC strains 9811M7A, 6249, and twenty-five of the oral strains. Group II consisted of ATCC strain 903 and the remaining eight oral strains all of which reacted with antisera for both Groups O and N. The chemical composition of the cell wall may explain this difference in antigenicity. The cell wall of all strains examined contained alanine, glutamic acid, lysine, aspartic acid, arginine, tyrosine, galactosamine, glucosamine and muramic acid. No quantitative differences in amino acids or amino sugars were found between any of the strains. The differences were in the quantity of cell wall sugars. The sugars found were glucose, rhamnose, galactose, mannose, and arabinose. Serological group I contained a slightly detectable amount of arabinose, while Group II possessed only a trace of arabinose.