Enterohemorrhagic E. coli Infections
Laura W. Lamps, MD
Key Facts
Terminology
Most common strain of EHEC is O157:H7, but there are others
Etiology/Pathogenesis
Infection usually acquired from contaminated food
Clinical Issues
Bloody diarrhea, severe abdominal cramps
Fever is mild or absent; fecal leukocytes absent
Macroscopic Features
Right colon most often involved
Microscopic Pathology
Histologic features mimic ischemia due to other causes
Strongly consider in younger patients with right-sided appearance of ischemia
May have pseudomembranes mimicking C. difficile
 Hematoxylin & eosin shows mucosal hemorrhage and lamina propria hyalinization, along with crypt withering and sloughing of the superficial mucosa. This biopsy specimen came from a patient with EHEC. |
 Hematoxylin & eosin shows prominent fibrin thrombi  in the superficial submucosa. This is a common finding in an EHEC infection. |
TERMINOLOGY
Abbreviations
Enterohemorrhagic E. coli (EHEC)
Synonyms
E. coli O157:H7
Definitions
Infection by enterohemorrhagic strain of gram-negative bacterium E. coli
Most common strain is O157:H7, but there are others
Produces cytotoxin similar to Shigella
Bacteria adhere to but do not invade tissue
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