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': 'Catalase positive, beta-hemolytic Staphylococcus is \nSelect and explain. \nA. Staphylococcus aureus, B. Staphylococcus epidermidis, C. Staphylococcus saprophyticus, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Staphylococcus aureus is beta hemolytic, produce a sharply defined clear colorless zone of hemolysis on blood agar within which red cells are completely absent. Staphylococcus aureus is catalase positive. Catalase test: place a loopful of hydrogen peroxide on colonies on the nutrient agar. Prompt effervescence indicates catalase production. Ref: Textbook of Microbiology; Ananthanarayanan and Panicker; 10th Edition; Page no: 207', 'role': 'assistant'}]