[765] Histological Findings in Acutely Symptomatic Ulcerative Colitis Patients with Superimposed Clostridium difficile Infection

Tao Wang, Larissa Matukas, Catherine J Streutker. University of Toronto, Toronto, ON, Canada; St. Michael's Hospital, Toronto, ON, Canada

Background: In patients with acutely symptomatic ulcerative colitis (UC), pathologists may be asked to differentiate between a UC flare versus superimposed infection. Ulcerative colitis patients are prone to Clostridium difficile infection and UC patients tend to have worse outcomes when C. difficile positive. However, no recent studies have examined whether it is possible to detect histological evidence of C. difficile related colitis in the setting of acute UC. If stool testing has not been performed, histological suspicion may prompt earlier testing and treatment.
Design: The microbiology database at St. Michael's Hospital was searched for UC patients tested for C. difficile by stool enzyme immunoassay (2004-2011). 10 Patients with a diagnosis of ulcerative colitis with colonic biopsies taken during a flare that coincided with a positive C. difficile (C. difficile +) test were identified. 32 controls were found who were biopsied during a UC flare but tested negative for C. difficile (C. difficile -) Slides from these cases were reviewed by a gastrointestinal pathologist who was blinded to patient cohort. Features examined included evidence of pseudomembranes (defined as “mushroom” shaped fibrinopurulent exudate at the mucosal surface), degree of active and chronic colitis, and presence of lamina propria hemorrhage and neutrophils. Endoscopy reports were examined for comments regarding macroscopic pseudomembranes. Statistical analysis was performed with two-tailed Fisher's exact test.
Results: In C. difficile + patients, 4 of 10 (40%) had microscopic pseudomembranes. In controls, 4 of 32 (13%) demonstrated pseudomembranes. This difference approached but fell short of significance (p=0.076). Only one of the C. difficile + patients and none of the controls had endoscopically evident pseudomembranes. There were no differences in the severity of colitis on biopsy between C. difficile + and negative patients, with most having moderate acute and chronic colitis. The presence of hemorrhage or neutrophils in the lamina propria did not correlate with C. difficile positivity.
Conclusions: There are no specific features which separate UC patients with and without C. difficile infection. However, the presence of microscopic pseudomembranes is suggestive of super-imposed C. difficile infection in UC patients. While it is not particularly sensitive or specific, commenting on this histological feature may prompt earlier microbiologic definitive testing and treatment.
Category: Gastrointestinal

Monday, March 19, 2012 1:00 PM

Poster Session II # 131, Monday Afternoon


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