What is the recommended dosing of Vancomycin (Vanco) for Clostridioides difficile (C. diff) infection?

Vancomycin Dosing for Clostridioides difficile Infection

For C. difficile infection, oral vancomycin should be dosed at 125 mg four times daily for 10 days for initial non-severe episodes, and 500 mg four times daily for 10 days for severe or fulminant cases. 1

Classification and Initial Assessment

Disease severity determines the appropriate vancomycin dosing:

• Non-severe CDI: WBC ≤15,000 cells/mL and serum creatinine <1.5 mg/dL
• Severe CDI: WBC ≥15,000 cells/mL or serum creatinine >1.5 mg/dL
• Fulminant CDI: Hypotension, shock, ileus, or megacolon

Vancomycin Dosing Recommendations by Disease Severity

Initial Episode - Non-severe CDI

• Preferred regimen: Vancomycin 125 mg orally four times daily for 10 days 1
• Alternative: Fidaxomicin 200 mg twice daily for 10 days

Initial Episode - Severe CDI

• Preferred regimen: Vancomycin 125 mg orally four times daily for 10 days 1
• Alternative: Fidaxomicin 200 mg twice daily for 10 days

Initial Episode - Fulminant CDI

• Preferred regimen: Vancomycin 500 mg orally four times daily for 10 days 1
• If ileus present: Add rectal vancomycin 500 mg in 100 mL normal saline every 6 hours as retention enema
• Add IV metronidazole 500 mg every 8 hours, particularly if ileus is present

When Oral Administration is Not Possible

• Non-severe CDI: IV metronidazole 500 mg three times daily for 10 days 1
• Severe CDI: IV metronidazole 500 mg three times daily PLUS rectal vancomycin 500 mg in 100 mL normal saline every 4-12 hours 1

Recurrent CDI Treatment

First Recurrence

• If metronidazole was used initially: Vancomycin 125 mg four times daily for 10 days 1
• If standard vancomycin was used initially: Consider tapered and pulsed vancomycin regimen 1
  • 125 mg four times daily for 10-14 days
  • 125 mg twice daily for 7 days
  • 125 mg once daily for 7 days
  • 125 mg every 2-3 days for 2-8 weeks

Second or Subsequent Recurrences

• Preferred regimen: Vancomycin in tapered and pulsed regimen as described above 1
• Alternatives:
  • Vancomycin 125 mg four times daily for 10 days followed by rifaximin 400 mg three times daily for 20 days
  • Fidaxomicin 200 mg twice daily for 10 days
  • Consider fecal microbiota transplantation

Pediatric Dosing

• Non-severe CDI: Vancomycin 10 mg/kg/dose (maximum 125 mg) four times daily for 10 days 1
• Severe or fulminant CDI: Vancomycin 10 mg/kg/dose (maximum 500 mg) every 8 hours for 10 days 1

Important Clinical Considerations

1. Always discontinue the inciting antibiotic as soon as possible to reduce recurrence risk 1, 2

2. Avoid antiperistaltic agents and opiates as they may mask symptoms and potentially worsen disease 1, 2

3. Monitor for treatment response within 3 days (decreased stool frequency, improved consistency) 2

4. Early surgical consultation for patients with:

   • Perforation of the colon
   • Systemic inflammation not responding to antibiotics
   • Toxic megacolon or severe ileus
   • Serum lactate >5.0 mmol/L 1, 2

5. Vancomycin resistance concerns: Studies show no increased risk of vancomycin-resistant enterococci (VRE) with oral vancomycin compared to metronidazole 3

Common Pitfalls to Avoid

• Underdosing in severe disease: Using 125 mg dosing for fulminant CDI instead of the recommended 500 mg four times daily 1

• Failure to consider alternative routes: Not using rectal vancomycin when ileus is present 1

• Inappropriate duration: Standard course should be 10 days; shorter courses may lead to treatment failure 1, 4

• Not recognizing recurrence: Up to 20% of patients may experience recurrence, requiring different management strategies 5

• Continuing inciting antibiotics: Failure to discontinue the original antibiotic that triggered CDI significantly increases recurrence risk 1, 2