Comparative Value of Sigmoidoscopy and Stool Cytotoxin-A Assay for Diagnosis of Pseudomembranous Colitis

Abstract

Objective: Clostridium difficile associated diarrhea (CDAD) is an important hospital acquired infection. CDAD has shown variable range of clinical manifestation, from mild diarrhea to life threatening pseudomembranous colitis. Stool C. difficile cytotoxin-A assay has been used clinically and commonly for diagnosis of CDAD. However, the incidence and severity of CDAD show increasing tendency with frequent use of antibiotics, rapid diagnosis and management is required for severe CDAD. Although flexible sigmoidoscopic examination is recognized to allow rapid diagnosis of pseudomembranous colitis, its role in the management of patients remains to be determined. We compared diagnostic value of sigmoidoscopy with that of stool cytotoxin-A assay for diagnosis of pseudomembranous colitis. Methods: Hospital inpatients with CDAD were studied prospectively. Both flexible sigmoidoscopy and enzyme immunoassay for stool cytotoxin-A were performed and compared its diagnostic yield. The clinical manifestation and used antibiotics were analyzed. Results: Of 28 patients with CDAD, 18 patients (64.3%) showed pseudomembranous colitis at sigmoidoscopy. In two cases of pseudomembranous colitis, ascites and pleural effusion were developed. Most frequent antibiotics presumed to be cause of CDAD is cephalosporin. In patients with pseudomembranous colitis, the stool C. difficile cytotoxin assay was negative in 36.8%. With the stool cytotoxin-A assay, the diagnosis for CDAD was delayed to mean 4.7 days. Conclusion: In parallel with increasing use of antibiotics, the incidence and severity of CDAD increased. Flexible sigmoidoscopy is superior to the stool cytotoxin-A test in a subgroup of patients with pseudomembranous colitis. The rapid diagnosis by sigmoidoscopy is more helpful in management of severe CDAD and its use should be considered in suspected pseudomembranous colitis.