S4988 Ulcerative Colitis Unmasked by a Clostridioides difficile Infection: A Case Report

Introduction: Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting over 900,000 individuals in the United States, with an annual incidence of 9–20 cases per 100,000 people. While typically diagnosed in younger adults, up to 15% of cases present after age 60. Clostridioides difficile infection is a known trigger for colonic inflammation and may unmask underlying IBD. Differentiating post-infectious colitis from new-onset UC can be challenging. We present a case of elderly-onset UC diagnosed following persistent diarrhea after C. difficile infection, highlighting the importance of considering IBD in refractory cases. Case Description/Methods: A 77-year-old man with CAD (post-CABG/PCI) and type 2 diabetes presented with 2 months of profuse green, watery diarrhea (>20×/day), fecal incontinence, and a 40-pound weight loss. Symptoms began after completing a 7-day course of Cefdinir. He denied GI bleeding, fever, recent travel, or sick contacts. There was no prior history of IBD, IBS, celiac disease, or pancreatitis. He initially tested positive for C. difficile and was treated with a 2-week course of oral vancomycin, with only brief symptom improvement. Due to ongoing weight loss and persistent diarrhea, he presented to the emergency department. He appeared pale but was stable. Abdominal exam revealed decreased bowel sounds; labs showed iron deficiency anemia, elevated erythrocyte sedimentation rate (98), C-reactive protein (54), fecal calprotectin >1200, positive FIT, and normal white blood cells and platelets. Computed tomography abdomen/pelvis showed diffuse colonic wall thickening from the transverse colon to the rectum, consistent with proctocolitis. A colonoscopy revealed continuous severe inflammation from the rectum to the cecum with friability, granularity, and ulcerations—most pronounced in the left colon. Biopsies showed active colitis with chronic architectural changes. He was started on intravenous methylprednisolone, transitioned to a prednisone taper, and initiated on vedolizumab. He reported symptom improvement, with C-reactive protein decreasing from 54 to 13, and he was referred to the IBD clinic for ongoing care. Discussion: Persistent diarrhea after C. difficile treatment should prompt evaluation for underlying IBD. In this case, weight loss, elevated inflammatory markers, and chronic colitis on biopsy supported new-onset ulcerative colitis. C. difficile may unmask IBD, especially in older adults with atypical symptoms. Early colonoscopy is essential when symptoms persist. The patient improved with corticosteroids and vedolizumab, aligning with standard UC therapy.