Background: In Inflammatory bowel disease (IBD), reactivation of human cytomegalovirus colitis (CMV) infection can occur as a result of chronic immunosuppression and local inflammation in the bowel wall . CMV reactivation is common in patients with severe colitis, with a reported prevalence of 4.5–16.6% , and occurs more frequently in ulcerative colitis (UC) than Crohn's disease (CD), possibly due to their different cytokine profile. CMV colonic disease can exacerbate UC disease activity, and has been associated with decrease response to corticosteroids/ immunosuppressive therapy , higher colectomy rates  and longer hospitalisation stay. However, it remains controversial if anti-viral therapy alters the course of UC; there is also a lack of data on the prevalence of CMV colonic disease in Asian IBD patients. We aim to determine the prevalence of CMV colonic disease and clinical course in Asian patients with acute exacerbation of UC in Singapore, a multiracial country consisting predominantly of Chinese, Malays and Indians.
Methods: Electronic records of 125 patients with ulcerative colitis (UC) who were hospitalised for acute exacerbation from 2002- October 2016 were retrospectively reviewed. Biodata, clinical presentation and treatment information was extracted. The diagnosis of CMV colonic disease was based on histological identification of CMV inclusion bodies and/or positive immune-histochemistry (IHC). The severity of UC was graded according to Truelove and Witt's criteria.
Results: There were 125 (65% Male; 56% Chinese; 23% Indian, 12% Malay, 9% others) UC patients with 205 admissions to hospital. Of these, 39 patients had 78 admissions for acute exacerbation of disease activity (6% Mild, 27% Moderate, 68% Severe, 2% Fulminant). Four patients (5.1%) were diagnosed with CMV colonic disease, including 1 patient with newly diagnosed UC; of these, 3 were steroid-refractory and 2 were on long-term azathioprine, 2 had deep colonic ulcers at endoscopy and CMV DNA (colon biopsy) ranged 5400–290000 copies/mg. All patients received anti-viral therapy: 2 responded well and achieved steroid-free remission; 2 failed to respond (including 1 who failed infliximab rescue therapy) and subsequently underwent total colectomy. CMV tissue DNA load, presence of deep colonic ulcers did not predict response to treatment or clinical outcome.
Conclusions: The prevalence of CMV colonic disease was 5% in Asian UC patients with acute exacerbation. Anti-viral therapy conferred benefit in only some patients who subsequently achieve steroid-free remission. Larger studies are needed to determine prognostic factors and identify subgroups that will benefit from anti-viral therapy.
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