A diagnostic dilemma: cytomegalovirus colitis as an uncommon comorbidity in inflammatory bowel disease: a case report.

Background: The role of cytomegalovirus infection as an opportunistic pathogen in exacerbating ulcerative colitis and its response to treatment remain a topic of ongoing debate. Clinicians encounter numerous challenges, including the criteria for differentiating between an acute ulcerative colitis flare and true cytomegalovirus colitis, the diagnostic tests for identifying cytomegalovirus colitis, and determining the appropriate timing for initiating antiviral therapy.

Case presentation: A 28-year-old Syrian female with a seven-year history of pancolitis presented with worsening bloody diarrhea, abdominal pain, and tenesmus despite ongoing treatment with azathioprine, mesalazine, and prednisolone. She experienced a new flare of acute severe ulcerative colitis despite recently completing two induction doses of infliximab (5 mg/kg) initiated four weeks prior for moderate-to-severe ulcerative colitis. She had no prior surgical history. Her symptoms included watery, bloody diarrhea occurring nine to ten times per day, abdominal pain, and tenesmus. Initial laboratory tests indicated anemia, leukocytosis, elevated C-reactive protein (CRP) and fecal calprotectin levels, and positive CMV IgG. Stool cultures, Clostridium difficile toxin, testing for Escherichia coli and Cryptosporidium, and microscopy for ova and parasites were all negative. Sigmoidoscopy revealed numerous prominent erythematous area with spontaneous bleeding. Biopsies demonstrated CMV inclusions confirmed by immunohistochemistry, although prior biopsies were negative. We tapered prednisolone and azathioprine and initiated ganciclovir at 5 mg/kg for ten days, followed by valganciclovir at 450 mg twice daily for three weeks. After one month, she showed marked improvement, with CRP and fecal calprotectin levels returning to normal. She scored one point on the partial Mayo score. The third induction dose of infliximab was administered on schedule, and azathioprine was resumed.

Conclusion: Concurrent cytomegalovirus infection in patients with inflammatory bowel disease presents a significant clinical challenge due to its associated morbidity and mortality. Diagnosing and managing this condition is particularly difficult, especially regarding the initiation or continuation of immunosuppressive therapies.