This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'A child presents with infective skin lesion of the leg. A culture was done which showed gram+ve cocci in chains which were hemolytic colonies. The test to confirm the organism is \nSelect and explain. \nA. Bile solubility, B. Optochin sensitivity, C. Bacitracin sensitivity, D. Catalase positive', 'role': 'user'}, {'content': "Answer: C \nExplanation: The culture is suggestive of infection with Streptococcus pyogenes which is gram-positive, occurring in chains and beta-hemolytic. A convenient method for the identification of Streptococcus pyogenes is based on Maxted's observation that they are more sensitive to bacitracin than other streptococci. Bacitracin sensitivity test: A filter paper disc of 0.04U is applied on the surface of an inoculated blood agar. After incubation, a wide zone of inhibition is seen with Streptococcus pyogenes and not with other streptococci. Reference: Textbook of Microbiology; Anathanarayan and paniker's; 10th edition; Page no: 217", 'role': 'assistant'}]