P0631 DIFFICULTY IN DIAGNOSING PSEUDOMEMBRANOUS COLITIS IN INFLAMMATORY BOWEL DISEASE (IBD)

Abstract

Introduction: Clostridium difficile (C. diff) infections are commonly seen in patients with IBD, and may be seen both at initial presentation and during the course of the disease, often resulting in acute exacerbations. Diagnosis is routinely made by using rapid enzyme immunoassays (EIAs) which detect the presence of toxin A and B in stools. However in patients with severe diarrhea dilution of the toxin can occur, resulting in a negative test, delaying diagnosis and treatment which may lead to worsening of the clinical course Methods: We report two cases where the diagnosis of pseudomembranous colitis was made by colonoscopy. CASE 1: 16 yr old male with indeterminate colitis (IC) diagnosed at 8 yrs of age, previously well controlled on sulfasalazine alone. He presented with a one month history of increasing abdominal pain (AP), diarrhea (8–10 stools/day) and a 10 pound weight loss. Labs: ESR-4 (0–20), CRP-32 (<5), WBC count-14.5K (bands 10%). Only the last of three stool samples was positive for C. diff. Flagyl was given for one week. Due to worsening clinical course, colonoscopy was performed which revealed diffuse colitis with pseudomembranes in the transverse and distal colon. Although stool samples remained negative for C. diff., he was started on vancomycin and showed gradual improvement of hematochezia and AP. CASE 2: 20 yr old female with Crohn’s disease (CD), involving the colon and perineum, diagnosed at 3 yrs of age. She presented with a four day history of colicky AP, diarrhea (10–12 stools/day), and a 3 pound weight loss. She was on Flagyl (for a prior C. diff infection, 3 weeks earlier), Thalidomide, ciprofloxacil and prednisone. Labs: ESR-55 (0–20), CRP-66 (<5), WBC count-8.5K (bands 34%), 4 stool samples were collected and all were negative for C. diff. Colonoscopy revealed pancolitis with pseudomembranes throughout. Flagyl was discontinued and she was started on vancomycin with gradual improvement. Results: As seen from case 1, multiple stool assays may be necessary to diagnose C. diff infections in patients with IBD, and a negative test does not always rule out pseudomembranous colitis as seen in case 2. Conclusion: Routine diagnostic stool assays may not diagnose C. diff infections in patients with IBD, possibly due to a dilutional effect on toxin concentration from severe diarrhea. In patients in whom an infectious etiology is suspected, a limited colonoscopy may be helpful to diagnose and promptly treat pseudomembranous colitis in C. diff negative patients, leading to improvement in their clinical course