A 20-year-old woman presents with a 1-day history of passing bloody diarrhea. On examination, her temperature is 39 degrees centigrade. A stool examination reveals polymorphonuclear leukocytes, but no trophozoites.
What is the causative organism?
A) Entamoeba histolytica
B) Enterotoxigenic Escherichia coli
C) Shigella dysenteriae
D) Bacillus cereus
E) Norwalk virus
