clostridium%20difficile%20infection
CLOSTRIDIUM DIFFICILE INFECTION
Clostridium difficile infection is commonly associated with antibiotic treatment and is one of the most common nosocomial infections.
Symptoms usually start on days 4-9 of antibiotic treatment, but may also occur up to 8-10 weeks after discontinuation of antibiotics.
Discontinuation of antibiotics may be the only measure needed for patients with only mild diarrhea, no fever, no abdominal pain nor a high WBC count.
Cessation of antibiotics allows for reconstitution of the normal colonic microflora and markedly reduces risk of relapse.

Laboratory Tests

Enzyme-Linked Immunoassay for Toxin

  • Most common test used to detect C difficile toxins
  • Lower sensitivity (63-99%) compared to the cytotoxin assay, but highly specific
  • Results are available w/in 2-6 hours
  • The test may need to be repeated in patients who initially had negative test results, but in whom C difficile infection is highly suspected

Nucleic Acid Amplification Tests (NAATs)

  • Superior to enzyme immunoassay for toxins as a diagnostic test for C difficile infection
  • Used only in acute infections; false positives are of concern

Stool Cytotoxin Assay

  • Gold standard for the diagnosis of C difficile-mediated infection
  • Highly sensitive & specific
  • Disadvantages: Expensive, results only available after 24-48 hours, requires a tissue culture facility

Stool Culture

  • Not helpful in diagnosis because the test is not specific for pathogenic toxin-producing strains of C difficile

Other Diagnostic Exams

Blood Chemistry

  • May show electrolyte imbalance & evidence of dehydration
    • Serum lactate may serve as indicator of disease severity before performing surgical treatment

Stool Exam

  • Grossly bloody stools are rare, but occult blood may be present in severe colitis

Sigmoidoscopy or Colonoscopy

  • Consider if there is a delay or difficulty in laboratory tests for C difficile

Imaging

Endoscopy

  • Indications for endoscopy
    • When there is a need for rapid diagnosis (eg fulminant disease)
    • In a patient who cannot produce stool because of ileus
    • As part of testing for other colonic diseases
    • May be considered in patients in whom laboratory exams for C difficile are negative but suspicion of the infection remains high
  • The pseudomembranous finding on bowel mucosa or on examination of a biopsy sample is pathognomonic of C difficile colitis
  • Findings may be normal in mild disease or may show only nonspecific colitis in moderate cases
  • Sigmoidoscopy alone may not detect abnormalities when lesions are confined to the right colon
  • Colonoscopy & sigmoidoscopy may be contraindicated in patients w/ fulminant colitis because of the risk of perforation

Computed Tomography (CT) Scan

  • Not useful in confirming the diagnosis of early or mild colitis
  • May be used as a confirmatory procedure for suspected C difficile infection when thickening of colonic mucosa is seen
  • Can quickly diagnose fulminant disease
    • Abdominal & pelvic CT scan may be done in patients w/ complicated infection
  • In cases involving the right colon, may reveal bowel wall edema & inflammation
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