This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'All are true about streptococcus except : \nSelect and explain. \nA. M-protein is responsible for production of mucoid colonies, B. M- protein is responsible for virulence, C. Mucoid colonies are virulent, D. No resistance to penicillin has been reported', 'role': 'user'}, {'content': 'Answer: A \nExplanation: “Mucoid colonies are due to production of capsule of hyaluronic acid not due to M protein.”\nHarrison 17/e, p 882\nGrowth characteristic of Strep. pyogenes :\n\nOn blood agar virulent stains forms matt or mucoid colonies while avirulent form glossy colonies.\nM, T, R are proteins found on outer part of cell wall and forms the basis of Griffith classification.\n\n– M protein - Acts as virulence factor and antibody against it are protective.\n– T and R protein - No relation to virulence\n\nStreptococci (Except enterococci) are usually susceptible to penicillin so option “d” is not completely wrong. As option “a” is completely wrong, that would be the answer.', 'role': 'assistant'}]