Pseudomembranous Colitis

Acute inflammatory condition of the colon caused by overgrowth of Clostridium difficile

Aetiology

Most common cause

  • Clostridium difficile

Predisposing factors:

  • Recent antibiotic therapy (particularly)
    • Clindamycin
    • Cephalosporins
    • Fluoroquinolones
    • Penicillins
  • Hospitalization or long-term care stay
  • Older age
  • Proton pump inhibitors (↓ gastric acid)
  • Immunosuppression
  • GI surgery
  • Inflammatory bowel disease

Pathophysiology

  1. Antibiotics disrupt normal gut flora → overgrowth of C. difficile
  1. Bacteria produce toxins A & B → mucosal inflammation & necrosis
  1. Formation of pseudomembranes (fibrin, mucus, leukocytes)
  1. Watery diarrhea, abdominal pain, systemic symptoms

Clinical presentation

Profuse watery diarrhea

  • Lower abdominal pain/cramping
  • Fever
  • Nausea, anorexia
  • Leukocytosis
  • Dehydration

Severe/complicated cases:

  • Bloody diarrhea (less common)
  • Hypotension
  • Renal failure
  • Toxic megacolon
  • Bowel perforation
  • Sepsis

Investigations

Laboratory

  • C. difficile toxin A/B assay (ELISA)
  • PCR for toxin genes (high sensitivity)
  • Stool culture (gold standard but slow)
  • Leukocytosis common

Imaging

  • CT abdomen:
    • Colonic wall thickening
    • Accordion sign
    • Pericolonic stranding

Endoscopy (if uncertain)

  • Yellow-white pseudomembranes on mucosa — diagnostic
notion image

Management

Supportive Care

  • Stop causative antibiotics if possible
  • Maintain hydration/electrolytes
  • Avoid antidiarrheals (risk of toxic megacolon)

Antibiotics

  • Mild cases: Metronidazole 500 mg/8 hr/PO for 10-14 days
  • Severe cases (hypotension, ileus, megacolon): Vancomycin 125 mg/6 hr/PO for 10-14 days

Complications

  • Toxic megacolon (life-threatening)
  • Perforation
  • Sepsis
  • Recurrence (20–30% of cases)
  • Chronic colitis