A 17 year old boy  complains of vomiting, non-bloody diarrhea, abdominal pain, fever, chills and loss of appetite for the past 3 days. He ate a salad at a restaurant prior to his diarrhea onset. Physical exam was remarkable for pallor, jaundice, and diffuse abdominal tenderness. Lab results were as follows:
Hemoglobin: 9.7 g/dL
Platelet: 110,000 /cu.mm
Creatinine: 3.6 mg/dL
blood urea nitrogen (BUN): 73 mg/dL
direct bilirubin: 2.4 mg/dL
lactate dehydrogenase (LDH): 881 IU/L (normal: 110-265 IU/L)
Peripheral blood smear showed a moderate number of schistocytes and helmet cells.  Shiga-like toxin-producing E. coli (STEC) stx1/stx2 were found in stools. 
He has no other underlying disease and he is not on any medications.