This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Streptococci, Subject name: Microbiology
[{'content': 'Early detection of Streptococcus pyogenes is by? \nSelect and explain. \nA. Bacitracin, B. Oxaciliicin, C. Methidllin, D. Optochin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) BacitracinREF: Jawetz Microbiology, 24th Ed, Ch. 15See previous questionStreptococcus pyogenes are PYR-positive (hydrolysis of L-pyrrolidonyl-2-naphthylamide) and usually are susceptible to bacitracin.', 'role': 'assistant'}]