C. difficile is a ubiquitous, spore-forming, gram-positive, anaerobic bacillus. The organism produces 2 toxins: toxin A (enterotoxin) acts on the intestinal mucosa to produce diarrhea; toxin B (cytotoxin) increases vascular permeability in low doses.
Normal gut flora appears to be protective. Administration of antibiotics that impair growth of normal flora but not C. difficile is the most common risk factor, but any process that disrupts the normal bowel flora (weaning, chemotherapy) or bowel motility (bowel stasis, bowel surgery) predisposes to C. difficile–associated diarrhea. Inflammatory response contributes to the diarrhea and formation of pseudomembranes.
Clinical symptoms vary widely. Asymptomatic colonization is common in infants and young children. Illness varies from a mild self-limited diarrhea without pseudomembranes, to explosive watery diarrhea with occult blood, to the classic picture of pseudomembranous colitis with bloody diarrhea accompanied by fever, cramps, abdominal pain, nausea, and vomiting. Disease may develop during and as long as several weeks after antibiotic therapy. Severe and extensive colitis occurs in children undergoing chemotherapy or those with Hirschsprung disease or inflammatory bowel disease; it has been reported in a few children with cystic fibrosis. C. difficile disease occasionally involves the small gut; in some hosts, bacteremia and abscess formation have been reported.
The diagnosis is confirmed by detecting C. difficile or its toxin in the stool of a patient with significant diarrhea or colitis in the setting of prior or current antimicrobial use.
The 1st and essential step in treatment is the discontinuation of the current antibiotics, if possible, which is sufficient in most cases in combination with appropriate fluid and electrolyte replacement.
If symptoms persist, antibiotics cannot be discontinued, or the illness is severe, then oral metronidazole (20–40 mg/kg/day divided every 6–8 hr PO) or vancomycin (25–40 mg/kg/day divided every 6 hr PO) should be given for 7–10 days.
Oral metronidazole is the preferred therapy for most children because it is less expensive, has an excellent response rate, and minimizes the emergence of vancomycin-resistant