What is the recommended course of Florastor (Saccharomyces boulardii) for a patient with a history of Clostridioides difficile (C. difficile)?

Florastor (Saccharomyces boulardii) for Patients with History of C. difficile

For patients with a history of C. difficile infection, Florastor (Saccharomyces boulardii) should be used at 1 gram daily for 28-30 days in combination with standard antibiotic therapy specifically for recurrent CDI, not for initial episodes or primary prevention. 1, 2

Current Guideline Recommendations

The 2020 AGA guidelines make a conditional recommendation for S. boulardii in adults and children on antibiotic treatment for prevention of C. difficile infection, but notably recommend probiotics only in the context of clinical trials for patients with active CDI. 1 This represents a significant limitation in routine clinical use.

The 2018 IDSA/SHEA guidelines are even more cautious, stating that probiotics including S. boulardii have shown promise but none has demonstrated significant and reproducible efficacy in controlled clinical trials for CDI prevention or treatment. 1

Evidence-Based Dosing for Recurrent CDI

When S. boulardii is used (recognizing the guideline limitations above), the evidence supports:

• Dosage: 1 gram daily (500 mg twice daily) 2, 3
• Duration: 28-30 days 2, 3
• Timing: Started concurrently with antibiotic therapy and continued after antibiotics complete 2, 3

Specific Clinical Scenarios

For recurrent CDI (≥1 prior episode):

• S. boulardii combined with high-dose vancomycin (2 g/day for 10 days) showed recurrence rates of 16.7% versus 50% with placebo (P=0.05) 3
• When combined with standard-dose vancomycin or metronidazole, recurrence rates were 34.6% versus 64.7% with placebo (P=0.04) 2
• The benefit is only established for recurrent disease, not initial episodes 2

For initial CDI episodes:

• No demonstrated benefit: recurrence rate 19.3% with S. boulardii versus 24.2% with placebo (P=0.86) 2
• Do not use S. boulardii for first-time CDI 1, 2

Critical Caveats and Contraindications

Absolute contraindications:

• Immunosuppressed patients (AIDS, active chemotherapy within 3 months) were excluded from trials due to fungemia risk 2
• Central venous catheters present risk for line-related fungemia 1

Common side effects:

• Increased thirst and constipation 4
• Generally well-tolerated with no serious adverse reactions in immunocompetent patients 2, 3

Practical Algorithm for Use

1. Determine CDI episode number:

   • Initial episode → Do not use S. boulardii; treat with vancomycin or fidaxomicin per IDSA guidelines 1
   • First recurrence → Consider S. boulardii with vancomycin (preferably high-dose 2g/day) 3
   • Multiple recurrences → S. boulardii with tapered/pulsed vancomycin or consider FMT 1

2. Screen for contraindications:

   • Check immune status, recent chemotherapy, central lines 2

3. If proceeding with S. boulardii:

   • Start 1 gram daily with antibiotic therapy 2, 3
   • Continue for 28-30 days total (extending beyond antibiotic completion) 2, 3
   • Monitor for recurrence over subsequent 4 weeks 2

Important Limitations

The 2019 WSES guidelines note that evidence for probiotics is strain-specific and disease-specific, and many meta-analyses inappropriately pool different probiotic strains together. 1 The efficacy data specifically applies to S. boulardii strain I-745, not other Saccharomyces preparations. 1

The strongest evidence supports S. boulardii only as adjunctive therapy for recurrent CDI in immunocompetent patients, not for primary prevention or initial episodes. 1, 2, 3 Given guideline recommendations favoring clinical trial use only, routine prescription outside research protocols remains controversial. 1