Lancefield group of streptococci is based on: (A) M proteins, (B) Carbohydrate ( C ) antigen on the cell wall, (C) Bile solubility, (D) Sugar fermentation
Answer is B. Carbohydrate contained in the cell wall of many streptococci forms the basis of serologic grouping into Lancefield groups A-H and K-U. The serologic specificity of the group-specific carbohydrate is determined by an amino sugar.Jawetz 23e pg: 213