Clostridium difficile invasion and toxin circulation in fatal pediatric pseudomembranous colitis.

The direct involvement of Clostridium difficile in the lesional tissue of pseudomembranous colitis has not been demonstrated; the organism's effects have been assumed to be strictly toxin mediated. Because C. difficile cytotoxin may be found incidentally in the intestinal lumina of asymptomatic infants, the role of the organism in a variety of pediatric intestinal diseases is uncertain. The authors studied seven cases of fatal pediatric pseudomembranous colitis in which the presence of C. difficile was uniformly demonstrable in lesional tissues with the use of both an intestinal spore stain and a specific immunostain. The patients had either underlying Hirschsprung's disease or hematologic malignancy; the striking pathologic features peculiar to these patients were altered mucosal mucin and immunologic barriers in the former group and neutropenia in the latter. Two patients had demonstrable circulating cytotoxin in serum or ascitic fluid, and C. difficile was identified invading colonic mucosa or submucosa. Such phenomena did not occur in control pediatric patients with multiple other intestinal lesions. Altered host factors may be responsible for the intestinal invasion of C. difficile and its systemic toxin circulation in cases of fatal pediatric pseudomembranous colitis.