The diagnosis can best be made by the finding of C. difficile toxin in the stool along with characteristic changes in the colonic mucosa. Endoscopy should be carried out as soon as the diagnosis is suspected. The classic proctoscopic findings of raised yellow white plaques are diagnostic. Histologic exam confirms the presence of necrosis and pseudomembranes, which may be extensive or focal and more superficial. Although the colon is the usual site of disease, there have been cases of small bowel involvement.
Barium enema is contraindicated because of the risk of perforation.
The use of antibiotics prior to the onset of the disease is almost always associated with pseudomembranous enterocolitis with the most common antibiotics reported being ampicillin, amoxicillin, and cephalosporins. Once the diagnosis is made, immediate supportive therapy includes rehydration, electrolyte replacement, and discontinuation of the antibiotic involved. Many patients respond dramatically to discontinuation of the antibiotic. The use of antimicrobial agents in the treatment of pseudomembranous enterocolitis should be reserved for those patients with severe disease or in whom the diarrhea fails to improve spontaneously within 48 hours. The drug of first choice to be used in pseudomembranous enterocolitis is vancomycin.