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: Medicine
Bacteria most frequently cultured in the setting of emphysematous cholecystitis is: 
Select and explain. 
A. Clostridium, B. Streptococcus, C. Salmonella, D. Klebsiella
A: Clostridium
Answer: A: Clostridium 
Explanation: Bacteria most frequently cultured in emphysematous cholecystitis include anaerobes, such as C. welchii or C. perfringens, and aerobes, such as E. coli. This condition occurs frequently in elderly men and in patients with diabetes mellitus. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 2622