Senior Consultant, Dept. of Gastroenterology and HepatologyIndraprastha Apollo Hospitals, New Delhi

A 35-year-old female, diagnosed with ulcerative colitis (UC) since 10 years presented with acute diarrhea, 5-6 loose motions/day with blood and mucous associated with pain lower abdomen, low-grade fever, anorexia and malaise since 10 days. The patient was on 5-aminosalicyclic acid (5-ASA) as maintenance therapy. She had recently taken a holiday trip.

Lab tests showed hemoglobin (Hb) 11.8 g/dL, white blood cell count 9,500/mm3, C-reactive protein (CRP) 50 mg/L, erythrocyte sedimentation rate (ESR) 15 mm/hour and serum albumin 3.2 g/dL. Stool samples were negative for ova and parasites on routine microscopy. Three sequential stool cultures were negative for any infective pathology. She was put on intravenous (IV) steroid treatment, but despite IV steroids, the diarrhea worsened and became bloody. Colonoscopy was done which showed inflammation, bleeding and friability of the mucosa from the rectum to beyond the sigmoid colon. Multiple biopsies taken from the rectum and sigmoid colon showed focal flask-shaped mucosal ulceration due to invasive amebiasis, and Entamoeba histolytica parasites were evident. Steroids were discontinued and the patient was put on metronidazole 750 mg thrice-daily for 10 days, followed by oral diloxanide furoate 500 mg thrice-daily for 10 days. Her symptoms resolved and the patient was put on 5-ASA as maintenance treatment.

Diagnosis

Ulcerative colitis with superadded E. histolytica infection.

DISCUSSION

Amebiasis is infection of the human gastrointestinal tract by E. histolytica, a protozoan parasite that is capable of invading the intestinal mucosa and may spread to other organs, mainly the liver.1 Intestinal amebiasis is still an important health problem in developing regions of the world.2 There are four clinical forms of invasive intestinal amebiasis, all of which are generally acute: Dysentery or bloody diarrhea, fulminating colitis, amebic appendicitis and ameboma of the colon. Dysenteric and diarrheic syndromes account for 90% of cases of invasive intestinal amebiasis.1 The chief complaint of patients with infectious colitis is diarrhea. Because the symptom is sometimes accompanied by bloody stool, it is important to distinguish the infectious colitis from UC. However, diagnosis can be complicated by the fact that inflammatory bowel disease (IBD) patients may have an accompanying infection as well.3 A recent study in Turkey showed that ameba infection in patients with IBD, especially those with UC, is more prevalent than in the normal population.4 The presence of intestinal protozoa infections could be a contributing cause of persistent activity despite medical treatment in our population.5

Stool microscopy is a relatively poor method for diagnosing intestinal amebiasis because it is time-consuming, laborious and requires specific expertise. Culture methods are often unrewarding, with a sensitivity of only about 50%.1 Sigmoidoscopy and/or colonoscopy can be performed either to diagnose amebiasis or to exclude other causes of the patients’ symptoms. Microscopy may reveal cysts or trophozoites in scrapings or biopsies, which are best taken from the edge of ulcers.6

Patients with documented UC in clinical remission also can develop acute infectious colitis and present with symptoms of a flare of UC. Thus, infections need to be excluded with each episode of disease exacerbation.7 Amebiasis should be sought and treated in every patient with UC.6

REFERENCES

1. Espinosa-Cantellano M, Martínez-Palomo A. Pathogenesis of intestinal amebiasis: from molecules to disease. Clin Microbiol Rev 2000;13(2): 318-31.
2. Ghosh PK, Mancilla R, Ortiz-Ortiz L. Intestinal amebiasis: histopathologic features in experimentally infected mice. Arch Med Res 1994;25(3): 297-302.
3. Jung SA. Differential diagnosis of inflammatory bowel disease: what is the role of colonoscopy? Clin Endosc 2012;45(3):254-62.
4. Ustun S, Dagci H, Aksoy U, et al. Prevalence of amebiasis in inflammatory bowel disease in Turkey. World J Gastroenterol 2003;9(8):1834-5.
5. Yamamoto-Furusho JK, Torijano-Carrera E. Intestinal protozoa infections among patients with ulcerative colitis: prevalence and impact on clinical disease course. Digestion 2010;82(1):18-23.
6. Addib O, Ziglam H, Conlong P. Invasive amebiasis complicating inflamma-tory bowel disease. Libyan J Med 2007;2(4):214-5.
7. Thukral A, Tiwari DN, Tripathi K. Ulcerative colitis presenting as toxic megacolon. J Assoc Physicians India 2010;58:519.