What is the management approach for pseudomembranous colitis?

Management of Pseudomembranous Colitis

For initial treatment of pseudomembranous colitis (C. difficile infection), discontinue the inciting antibiotic immediately and initiate oral vancomycin 125 mg four times daily for 10 days, which achieves clinical success rates of approximately 80% and is superior to metronidazole in severe disease. 1, 2

Initial Assessment and Diagnosis

Discontinue the inciting antibiotic immediately upon suspicion of C. difficile infection (CDI), as continued antibiotic use significantly increases recurrence risk. 1 If ongoing antibiotic therapy is essential for another infection, switch to agents less commonly associated with CDI: parenteral aminoglycosides, sulfonamides, macrolides, vancomycin, or tetracycline/tigecycline. 1

Consider empirical therapy while awaiting test results only if there is strong clinical suspicion for severe CDI, defined by fever, leukocytosis (WBC ≥15,000/mm³), hypoalbuminemia, or ≥10 unformed bowel movements per day. 1, 2 However, empirical therapy should generally be avoided in mild cases. 1

Medical Treatment Strategy

First-Line Antibiotic Therapy

Oral vancomycin 125 mg four times daily for 10 days is the preferred first-line treatment, particularly for severe disease. 1, 2 This regimen demonstrates:

• Clinical success rates of 81% in controlled trials 2
• Median time to diarrhea resolution of 4-5 days 2
• Superior efficacy compared to metronidazole in severe CDI 1

Oral metronidazole remains effective for mild-to-moderate disease and offers advantages of lower cost and reduced selection pressure for vancomycin-resistant enterococci. 1 However, metronidazole achieves lower colonic concentrations than vancomycin since it is absorbed in the small intestine, explaining its reduced efficacy in severe cases. 1

Severe or Complicated Disease

For patients with severe-complicated CDI showing signs of systemic toxicity, peritonitis, or worsening despite medical therapy, urgent surgical consultation is mandatory. 1, 3 Surgical intervention should be considered when patients develop:

• Signs of organ failure or peritonitis 3
• Worsening CT findings despite appropriate medical therapy 3
• Toxic megacolon (transverse colon diameter >5.5 cm) 1

Subtotal colectomy is the procedure of choice, with mortality rates of 14% compared to 100% mortality with left hemicolectomy. 3 The external appearance of the colon is often deceptively normal at laparotomy and should not influence the surgical decision. 3

Adjunctive Measures

Discontinue proton pump inhibitors if clinically feasible, though no randomized trials have definitively proven benefit from discontinuation. 1

Avoid antispasmodic and antidiarrheal agents (such as loperamide in high doses), particularly in neutropenic patients, due to theoretical risk of toxic megacolon. 1, 4

Provide supportive care including:

• Fluid and electrolyte correction 4
• Nutritional support if malnourished 1
• Subcutaneous heparin for thromboembolism prophylaxis in severe cases 1

Management of Recurrent Disease

Recurrence occurs in 18-25% of patients after initial successful treatment. 2 For first recurrence, retreatment with the same antibiotic regimen (vancomycin or metronidazole) is appropriate. 4

For multiple recurrences (≥2 episodes), consider newer agents such as fidaxomicin or bezlotoxumab, which significantly reduce recurrence rates compared to vancomycin. 1 Pulsed or tapered vancomycin dosing may also reduce recurrence risk. 1

Fecal microbiota transplantation (FMT) should be considered after failure of three courses of antibiotics for recurrent CDI, with excellent success rates even after initial FMT failure. 1 FMT should not be used as initial therapy. 1

Diagnostic Imaging Considerations

CT imaging assists with diagnosis and severity assessment in patients with clinical manifestations of severe-complicated disease, though sensitivity is only 52%. 1 Typical findings include colonic wall thickening >4 mm, accordion sign, peri-colonic stranding, and ascites. 1

Point-of-care ultrasound may be useful in critically ill patients who cannot be transported to the CT suite, showing thickened colonic wall with heterogeneous echogeneity and hyperechoic pseudomembranes. 1

Flexible sigmoidoscopy may be helpful when stool assays are negative but clinical suspicion remains high, though colonoscopy is hazardous in fulminant colitis due to perforation risk. 1

Common Pitfalls

Do not repeat testing after initiating treatment unless there are clear clinical changes, as test positivity does not correlate with treatment failure. 1

Pseudomembrane formation may not be visible in neutropenic patients, requiring endoscopic biopsy for diagnosis in this population. 1

The external appearance of the colon at surgery is often deceptively normal and should not deter subtotal colectomy when indicated. 3