C. difficile is a potential cause of diarrhea in any patient who has received antibiotics in the preceding 4 to 6 weeks. All antibiotics except parenteral aminoglycosides have been implicated. Infection can be asymptomatic but causes syndromes ranging from mild diarrhea to fulminant and fatal pseudomembranous colitis. Pseudomembranous colitis is more frequent in the elderly and the debilitated and in ICUs. Nosocomial acquisition of C. difficile can occur, and so patients with C. difficile present in stool cultures should be subject to enteric isolation procedures.
C. difficile produces toxins A and B which cause the colitis. These toxins can be detected by cytotoxic tissue culture assay or enzyme-linked immunoassays. About 80 per cent of patients with C. difficile toxin will be positive on the first stool sample tested, but up to three samples should be sent to exclude the diagnosis ( Manabe et a 1995).
Pseudomembranous colitis presents with diarrhea and abdominal pain or discomfort. Tenesmus, anorexia, nausea, or vomiting may also occur. Flexible procto/sigmoidoscopy may reveal the typical pseudomembranes, but their absence does not exclude the diagnosis; up to a third of patients have pseudomembranes only in the ascending colon. Toxic megacolon is a rare complication of pseudomembranous colitis. Increasing abdominal pain, abdominal distension, fever, and tachycardia in a patient with recent diarrhea are clues to the diagnosis. Half the patients with toxic megacolon present with shock or hypotension and all are sufficiently ill to need admission to an ICU. Toxic megacolon has a high morbidity; up to two-thirds of the patients may die despite active treatment.
Treatment includes cessation of antibiotics if possible, rehydration, and specific treatment to eradicate C. difficile. Metronidazole 250 mg or vancomycin 125 mg orally four times daily are alternatives for mild to moderate pseudomembranous colitis. Metronidazole is cheaper and, in most studies, equally effective. Severe colitis has been treated with increased doses of vancomycin (up to 500 mg orally every 6 h), with intravenous metronidazole 250 mg every 6 h added for toxic megacolon. Patients with toxic megacolon who deteriorate despite medical treatment need surgical review. Worsening abdominal pain and increasing colonic diameter are indications for subtotal colectomy.
Was this article helpful?