This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Gram Positive Bacilli, Gram Negative Bacilli), Subject name: Microbiology
A 4-year-old boy gives the history of bloody diarrhea and now hospitalized for oliguria and hypeension. With which organism is he most likely infected? 
Select and explain. 
A. Clostridium perfringens, B. Salmonella typhi, C. Enteroinvasive E. coli, D. Shiga toxin-producing E. coli
D: Shiga toxin-producing E. coli
Answer: D: Shiga toxin-producing E. coli 
Explanation: The case is descriptive of hemolytic uremic syndrome associated with infection with E. coli O157:H7. This strain of E. coli produces phage-associated Shiga toxins (Stx-1 and/or Stx-2) that are functionally and antigenically similar to that produced by Shigella dysenteriae. None of the other organisms listed are associated with hemolytic uremic syndrome, although some do cause a bloody diarrhea. C. perfringens causes watery diarrhea.