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
All of the following diseases are caused by staphylococcus aureus except 
Select and explain. 
A. Ecthyma, B. Bullous Impetigo, C. Carbuncle, D. Folliculitis
A: Ecthyma
Answer: A: Ecthyma 
Explanation: 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