A fecal isolate identified as E. coli produces clear colonies on MacConkey agar with sorbitol. You should suspect

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E. coli strains that are capable of producing Shiga toxins, also known as verotoxins, are referred to as Enterohemorrhagic E. coli (EHEC). Sorbitol-fermenting E. coli strains are typically indicative of EHEC which often cause severe diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. The inability to ferment sorbitol is one of the key characteristics that differentiate these strains from Enterotoxigenic E. coli (ETEC), which is associated with traveler's diarrhea. Shigella is not capable of fermenting sorbitol and would not grow on MacConkey agar containing sorbitol. Therefore, the correct answer is C) Enterohemorrhagic E. coli.

A Fecal Isolate Identified as E