This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Surgery
Which one of the folllowing organisms is not associated with synergistic gangrene 
Select and explain. 
A. Escherichia, B. Staphylococcus, C. Clostridium, D. Streptococcus
A: Escherichia
Answer: A: Escherichia 
Explanation: Necrotising fasciitis is a dangerous and rapidly spreading infection of the fascial planes leading to necrosis of the subcutaneous tissues and overlying skin. It is caused by b-haemolytic streptococci and, occasionally, Staphylococcus aureus, but may take the form of a polymicrobial infection associated with other aerobic and anaerobic pathogens, including Bacteroides, Clostridium, Proteus, Pseudomonas and Klebsiella. It is termed Fournier's gangrene when it affects the perineal area, and Meleney's synergistic gangrene when it involves the abdominal wall