Review Question - QID 213844

A 3-year-old boy is brought by his parents to the pediatrician with fevers, abdominal pain, and diarrhea for the past week. His diarrhea has been streaked with blood since earlier this morning. The boy has had a diminished appetite in the past week but had no recent change in diet prior to the onset of symptoms. His mother states that the parents of several preschool classmates of her son have mentioned that their kids have experienced similar symptoms in the past few weeks as well. On physical examination, the boy exhibits tenderness to palpation in the right lower quadrant of the abdomen. Ultrasonography is performed and shows a normal appendix without signs of inflammation. The patient is recommended treatment with supportive care. Which of the following organisms is most likely responsible for this boy’s symptoms?