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': 'How does staphylococcus aureus differ from staphylococcus epidermidis? \nSelect and explain. \nA. It is coagulase positive, B. It is a common cause of UTI, C. It forms white colonies on blood agar, D. It causes endocarditis in drug addicts', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Staphylococcus aureus is coagulase positive whereas staphylococcus epidermidis is coagulase negative. Other coagulase negative staphylococci are S haemolyticus, S saccharolyticus, S hominis, S schleiferi, S lugdunensis and S simulans. Test Staphylococcus aureus Staphylococcus epidermidis Coagulase Positive Negative Clumping factor Positive Negative Heat stable nuclease Positive Negative Urease Variable Negative Acid from mannitol Positive Negative Acid from trehalose Positive Negative Ref: Textbook of Microbiology and Immunology By Parija, Pages 188-190', 'role': 'assistant'}]