The Varied Manifestations of Amebic Colitis

Abstract

Purpose: Invasive amebiasis is common worldwide, but is seen infrequently in the United States. It is often not included in the initial differential diagnosis; however, it is associated with considerable morbidity in patients residing in or traveling to endemic areas. We report a series of interesting cases of patients with amebic colitis in a United States-Mexico border city to alert physicians to the varied manifestations of this condition. Methods: We analyzed the clinical and endoscopic manifestations of amebic colitis in patients identified in a retrospective chart review of patients who presented to Thomason General Hospital in El Paso, Texas between 10/99 and 4/09. Criteria for amebic colitis included demonstration of motile hematophagous trophozoites of Entamoeba histolytica in stool or histologic confirmation of invasive amebiasis in colonic tissue. Results: Nine patients were diagnosed with amebic colitis. Median age was 46 (range 38-83), 5 were males, and all were Hispanic. The main symptoms were diarrhea (67%), abdominal pain, hematochezia, abdominal distension, and fever. Two patients presented with gastrointestinal bleeding, not associated with diarrhea. Median duration of symptoms was from 7 to 14 days. The main physical finding was abdominal tenderness in 6/8 (75%) and an abdominal mass in 1 patient. The diagnosis of amebic colitis was established in the following ways: 7 patients by colonoscopy with biopsy, 1 by surgery for colonic obstruction, and 1 by positive stool smear done to evaluate dysentery. There was histologic confirmation of colonic amebiasis in 7/8 (88%) in whom tissue was obtained. All 7 patients in whom colonoscopy was done had inflammation with rectosigmoid involvement and 6/7 (86%) had ulcerations present. Infection resolved after treatment with metronidazole in most patients; however, 1 patient developed a liver abscess and another developed colonic perforation. Conclusion: 1) The occurrence of amebic colitis in this United States-Mexico border city hospital population was low, but potentially life-threatening. 2) The most common symptom was diarrhea, but physicians should be alert to the less common presentations of primarily gastrointestinal bleeding or of a surgical abdomen. 3) Of note, rectosigmoid involvement is typically found on colonoscopy.