This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacterial infections, Subject name: Dental
[{'content': 'All of the following diseases are caused by staphylococcus aureus except \nSelect and explain. \nA. Ecthyma, B. Bullous Impetigo, C. Carbuncle, D. Folliculitis', 'role': 'user'}, {'content': "Answer: A \nExplanation: STREPTOCOCCAL INFECTIONS Ecthyma:- * Deeper form of nonbullous impetigo with ulceration due to GAS but quickly contaminated by S. aureus. * Presents as 'punched out' shallow ulcer with thick, yellow-gray crust commonly in lower legs of children. * If diagnosis unceain - punch biopsy with deep-tissue Gram stain and culture. Treatment:- Dicloxacillin or first generation cephalosporin. Ref:- Sima Jain; pg num:-207", 'role': 'assistant'}]