A 12-year-old girl develops fever, abdominal pain, and bloody diarrhea 1 to 2 days after eating a hamburger at a fast food restaurant. Physical examination reveals an extensive purpuric skin rash. The patient develops oliguria, and laboratory studies show elevated serum levels of BUN and creatinine. Which of the following is the most likely etiologic agent responsible for this patient's condition?

Enterohemorrhagic E. coli (serotype 0157-H7), which may contaminate meat or milk, causes bloody diarrhea, which can be followed by the hemolytic-uremic syndrome. The organism adheres to the colonic mucosa and releases an enterotoxin that destroys epithelial cells. Patients present with abdominal pain, low-grade fever, and bloody diarrhea. Stool examination shows leukocytes and erythrocytes. Hemolytic-uremic syndrome is manifested by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Although they may be associated with bloody diarrhea, the other choices do not present with hemolytic-uremic syndrome.Diagnosis: Hemolytic-uremic syndrome, enterohemorrhagic E. coli