This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology Pa 1 (Gram Positive Cocci, Gram Negative Cocci), Subject name: Microbiology
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 both: 
Select and explain. 
A. Mec A gene is related to it, B. M protein is same, C. C carbohydrate antigen is same, D. Strains causing both are same
C: C carbohydrate antigen is same
Answer: C: C carbohydrate antigen is same 
Explanation: Both of above mentioned conditions are caused by Group A STREPTOCOCCUS . Option 1 mec A gene Found in bacterial cells Responsible for resistance to antibiotics such as methicillin, penicillin, erythromycin, tetracycline The most commonly known carrier of the mec A gene is MRSA. Option 2, 4 Strains causing skin infection and throat infection are different and belong to different 'M' serotypes. Option 3 The carbohydrate 'C' antigen is group specific, i.e. beta- hemolytic group A Streptococci (Str. pyogenes) have same 'C' antigen.