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': 'A 5-year-old child presents with pustular lesions on the lower legs. The culture from the lesion showed hemolytic colonies on blood agar which were Gram-positive cocci. Provisional diagnosis of Group A streptococcal pyoderma can be done by? \nSelect and explain. \nA. Catalase positivity, B. Optochin sensitivity, C. Bile solubility, D. Bacitracin sensitivity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Catalase positivity Pyoderma (Impetigo Superficial infection of the skin, caused primarily by Group A Streptococci and Staphylococci Usual site of infection are face (paicularly around nose and mouth) and the legs Diagnosis is based on the culture and staining of indeginous lesion. Gram positive cocci if catalase positive, than it is most likely to be Staphylococci and if catalase negative than it is Streptococci', 'role': 'assistant'}]