A 60-year-old woman has a sigmoid resection and colostomy for diverticulitis with rupture. That night she becomes confused, oliguric, and febrile. The area around the colostomy is indurated and crepitant. Most likely causal organism?
A) Clostridium difficile
B) Escherichia coli
C) Candida albicans
D) Clostridium perfringens