Clostridium difficile colitis (also known as pseudomembranous colitis) is a common cause of antibiotic-associated diarrhoea, and an increasingly encountered entity in sick hospitalized patients and if undiagnosed and untreated continues to have high mortality. It could be classified as a form of infectious colitis.
C. difficile infection is usually preceded by antibiotic use or chemotherapy and is therefore usually encountered in unwell, hospitalized patients with significant comorbidity.
Typically, patients present with diarrhoea, fever, raised white cell count and abdominal pain with distension.
Clostridium difficile is a gram-positive anaerobe which is not a normal bowel commensal, but rather colonises the bowel after the normal colonic biology has been disrupted. This is typically due to antibiotic use or chemotherapy within 6 weeks of presentation 1.
C. difficile produces two toxins (A and B) which have both cytotoxic and enterotoxic effects on the bowel. Clinical manifestation is thought to be predominantly due to toxin B 4.
An exudate composed of fibrin, white cells and cellular debris forms a pseudomembrane on the mucosa of the colon, which is characteristic 1. Definitive diagnosis is made by isolating C. difficile toxin in the a stool sample.
Signs and symptoms
Symptoms of C difficile colitis often include the following:
- Mild to moderate watery diarrhea that is rarely bloody
- Cramping abdominal pain
Physical examination may reveal the following in patients with the disorder:
- Fever: Especially in more severe cases
- Lower abdominal tenderness
- Rebound tenderness: Raises the possibility of colonic perforation and peritonitis
- Plain film: abdominal radiograph
Early in the disease, few findings may be evident. Bowel dilatation, mural thickening and thumbprinting (due to thickening of the haustral folds) are seen later. Eventually, in untreated or fulminant cases, appearances will be those of toxic megacolon 3, with subsequent perforation and free intraperitoneal gas.
- Fluoroscopy: barium
Barium studies demonstrate the same findings as plain radiography. Additionally, the pseudomembrane may be visible on double contrast studies. The role of barium enema has significantly reduced in the diagnosis of this entity due to the availability of CT and the risk of perforation 2.
Findings include 2:
- bowel wall thickening (most common)
- CT equivalent to thumbprinting
- accordion sign
- shaggy mucosal outline
- pericolic stranding
- peritoneal free fluid
Although typically the whole colon is involved, the right colon and transverse colon may be affected in isolation in up to 5% of cases 2
rectal involvement in the vast majority of cases (90-95%) 2
Treatment and prognosis
Treatment involves supportive therapy (fluid and electrolyte replacement) and eradication of C. difficile with antibiotics (usually vancomycin or metronidazole) 5.
A novel, if somewhat disturbing, treatment option is that of faecal transplant, whereby ‘healthy’ faecal matter is either administered via nasogastic tube or directly into the colon, after having been donated by a family member 5.
Untreated pseudomembranous colitis carries a high mortality from toxic megacolon and perforation.
Other causes of toxic megacolon and colitis include:
- neutropenic colitis
- inflammatory bowel disease
- ulcerative colitis
- Crohn’s disease
- ischaemic colitis
- radiation induced colitis
Treatment for CDI varies according to its severity. Interventions include the following:
- Asymptomatic carriers: No treatment is necessary
- Mild, antibiotic-associated diarrhea without fever, abdominal pain, or leukocytosis: Cessation may be the only treatment necessary
- Mild to moderate diarrhea or colitis: Metronidazole (oral or intravenous) or vancomycin (oral) for 10 days
- Severe or complicated disease: Vancomycin is considered to produce faster symptom resolution and fewer treatment failures than metronidazole; in fulminant cases, combined therapy with intravenous metronidazole and oral (or per rectum) vancomycin may be considered
Relapse occurs in 20-27% of patients. Once a patient has 1 relapse, the risk for a second relapse is 45%. Relapses should be treated as follows:
- First relapse: The choice of antibiotic should be based on the severity of C difficile diarrhea/colitis
- Subsequent relapses: For every relapse beyond the first, vancomycin (prolonged taper/pulsed regimen) or fidaxomicin with or without probiotics is recommended
- Among various investigational therapies, fecal microbiota transplantation (fecal enemas or infusion of donor feces through a nasoduodenal tube) has been reported to repopulate the colonic flora and treat recurrent CDI.