Oral Vancomycin for C. difficile Infection
For C. difficile infection, oral vancomycin should be administered at a dose of 125 mg four times daily for 10 days as the standard treatment regimen. 1, 2
Dosing Recommendations Based on Disease Severity
Non-severe CDI
- Vancomycin 125 mg orally four times daily for 10 days 1
- Alternative: Fidaxomicin 200 mg twice daily for 10 days 1
Severe CDI
- Vancomycin 125 mg orally four times daily for 10 days 1
- Alternative: Fidaxomicin 200 mg twice daily for 10 days 1
Fulminant CDI
- Vancomycin 500 mg orally four times daily for 10 days 1, 3
- Plus intravenous metronidazole 500 mg every 8 hours 1, 3
- If ileus present: Add rectal vancomycin 500 mg in 100 mL normal saline every 6 hours as retention enema 3
Treatment Duration
- Standard duration: 10 days 1, 2
- Extended treatment may be necessary for recurrent infections (see below)
Evidence Supporting Dosage
- Clinical trials have demonstrated that 125 mg four times daily is as effective as higher doses (500 mg four times daily) for non-fulminant disease, with equivalent clinical cure rates and time to resolution of diarrhea 4
- The FDA-approved dosage for C. difficile-associated diarrhea is 125 mg administered orally 4 times daily for 10 days 2
Management of Recurrent CDI
First Recurrence
- Vancomycin 125 mg four times daily for 10 days (especially if metronidazole was used for initial episode) 1
- Alternative: Fidaxomicin 200 mg twice daily for 10 days 1
Second or Subsequent Recurrences
- Vancomycin taper/pulse regimen: 1, 3
- 125 mg four times daily for 10-14 days, then
- 125 mg twice daily for 7 days, then
- 125 mg once daily for 7 days, then
- 125 mg every 2-3 days for 2-8 weeks
Pediatric Dosing
- For children: 10 mg/kg/dose four times daily (maximum 125 mg per dose) for 10 days 1
- Maximum dose should not exceed 2 g daily 2
Important Clinical Considerations
Monitoring
- Monitor for symptom resolution (decreased stool frequency, improved stool consistency) within 3 days of treatment initiation 1
- Follow patients for at least 8 weeks after treatment to assess for recurrence 3
- For elderly patients (>65 years), monitor renal function during and after treatment due to increased risk of nephrotoxicity 2
Adjunctive Measures
- Discontinue the inciting antibiotic as soon as possible to reduce recurrence risk 1, 3
- Review and discontinue unnecessary proton pump inhibitors 3
- Implement appropriate infection control measures including isolation until 48 hours after diarrhea resolution 3
Potential Adverse Effects
- Oral vancomycin is generally well-tolerated as it is poorly absorbed from the gastrointestinal tract 4
- However, clinically significant serum concentrations can occur in patients with inflammatory bowel disorders or renal insufficiency 2
- Increased risk of vancomycin-resistant Enterococcus (VRE) colonization with prolonged use 5, 6
Special Situations
- For patients unable to take oral medications, consider vancomycin administration via nasogastric tube 1
- For patients with ileus, add rectal vancomycin (500 mg in 100 mL normal saline every 6 hours) 1, 3
- Obtain prompt surgical consultation for patients with fulminant disease, perforation, toxic megacolon, or severe ileus 3
While recent evidence suggests fidaxomicin may have lower recurrence rates compared to vancomycin 7, oral vancomycin remains a first-line therapy for C. difficile infection due to its established efficacy, safety profile, and widespread availability.