Abstract
The clinical and pathologic features of six patients with proven verotoxin-producing Escherichia coli colitis are described. Clinical data, 25 biopsy specimens and two autopsies from these patients are reviewed. All presented with crampy abdominal pain and bloody diarrhea. Colonoscopic findings included edema, erythema, pseudomembranes and hemorrhage. On biopsy, two patients had ischemic colitis, one had pseudomembranous colitis and three had a combination of concurrent ischemic and pseudomembranous colitis. Four cases showed fibrin-platelet thrombi in mucosal capillaries and submucosal arterioles. The classical pattern of infectious colitis was not seen in these cases. Other nonspecific changes included patchy mucosal edema, congestion, focally prominent interstitial hemorrhage and mild, patchy increase of the lymphoplasmocytic component of the lamina. Ischemic necrosis was present in 10 of 25 biopsies (40%), pseudomembranes in seven of 25 biopsies (28%), and four of 25 biopsies (16%) showed both. Colon from one autopsy revealed edema, pseudo membranes and intramural infarction . Concurrent thrombotic thrombocytopenic purpura was clinically documented in three of six patients. It is concluded that, in the context of hemorrhagic colitis, the following observations are indicative of E coli 0157:H7: the combination of pseudomcmbranous and ischemic colitis; ischemic colitis in a young patient; or pseudomembranous colitis with Clostridium difficile-negative culture and toxin. Multiple biopsies are required to demonstrate the full-blown features. E coli 0157:H7 colitis should be added to the differential diagnosis of submucosal edema.