A boy with skin ulcer on leg, culture reveals beta hemolysis. Cultures from school children with sore throat some days back also revealed beta hemolysis. What is the similarity between bothaEUR'

C carbohydrate antigen is the same [Ref: Ananthnarayan 8/e p 205-101 fi Hemolysis in an organism causing skin infections and sore throat suggests streptococcus pyogenes or Group A streptococcus infection. Group A streptococcus commonly causes : Skin infections (impetigo, Erysipelas) Sore throat (pharyngitis) Streptococci are first classified on the basis of their hemolytic propeies The fi hemolytic streptococci or the hemolytic streptococci are fuher classified based on the nature of a carbohydrate antigen present in the cell wall. - This classification is based upon antigenic differences in the group specific polysaccharide located in the bacterial cell wall. - More than 20 serologic groups have been identified and are designated by letters (A - V) except 1 and G. The carbohydrate or the "C" antigen are "group specific" i.e.,a paicular group will have a specific antigen. - The "C antigen" or the carbohydrate antigen would be same in all the streptococci of a paicular group. Majority of streptococci that produce human infections belong to group "A" also known as streptococcus pyogenes. The group "A" streptococci are fuher subdivided into type specific antisera Griffith based on M proteins. "Streptococcus A" or streptococcus pyogenes is an impoant cause of human infections. The two most common infections associated with streptococcus are . ? Skin infections --> Impetigo, Erysipelas Throat infections --> Pharyngitis The streptococcus bacteria causing the two infections belongs to the same lancefield group they both have same carbohydrate A antigen in their cell wall but they have difference in their surface M protein, i.e. they belong to different strains of streptococcus A. -Base on M protein the streptococcal 'A' group is divided into 80 strains. - Different strains of streptococci are associated with different infections. The throat infection and the skin infection are caused by different strains of the same lancefield group of streptococci. - A paicular lancefied group is divided into different strains based on "M proteins". -The M protein in the strain causing pharyngitis is quite different from the strain causing impetigo. - But both these strains belong to the same lancefield group and contains the same carbohydrate (A) antigen. - Impetigo is caused by higher number of M types 49, 53-55 - Throat infection caused by lower number M types Serotypes 1, 12 The question asks about the similarity between the two bacterias which is the presence of same carbohydrate antigen in their cell wall.