What is the role of probiotics, such as Lactobacillus rhamnosus GG (LR GG) or Saccharomyces boulardii, in managing gastroenteritis in a general patient population?

Role of Probiotics in Gastroenteritis

Direct Recommendation for North American Practice

The American Gastroenterological Association recommends against using probiotics for acute infectious gastroenteritis in children in the United States and Canada, based on two large, high-quality multicenter trials showing no benefit. 1

Geographic Context Matters Critically

The evidence for probiotics in gastroenteritis is highly geography-dependent, creating a clinical paradox:

In North America (US/Canada):

• Do not use probiotics for acute gastroenteritis in children 1, 2
• Two rigorous multicenter trials (943 and 827 children) showed no benefit for either L. rhamnosus ATCC 53103 or the combination of L. rhamnosus R0011 with L. helveticus R0052 1
• Neither reduced moderate-to-severe gastroenteritis (Vesikari scale ≥9) compared to placebo 1
• Four separate North American studies confirmed lack of benefit 1

Outside North America:

• Probiotics may reduce diarrhea duration by approximately 22 hours (95% CI: 16.17-27.64 hours), though evidence quality is low 1
• The European Society for Paediatric Gastroenterology recommends L. reuteri DSM 17938 as adjunct treatment in children outside North America 2

Why This Geographic Difference Exists

The AGA explicitly states that differences in host genetics, diet, sanitation, and endemic enteropathogens between North America and other regions make non-North American studies non-generalizable to US/Canadian populations. 1

Evidence Quality Issues in Non-North American Studies:

• Most positive studies originated from India, Italy, Poland, Turkey, and Pakistan 1
• 27 of 31 recent studies had one or more concerns regarding risk of bias 1
• Over half of all children studied were enrolled in just three countries: India, Italy, and Poland 1

Strain-Specific Evidence (For Non-North American Settings Only)

If practicing outside North America, the following strains have the most evidence:

Saccharomyces boulardii:

• May reduce diarrhea duration by 28.9 hours (95% CI: 16.78-41.03 hours), but evidence quality is very low 1, 2
• Studied in 22 trials in children with acute gastroenteritis 1
• May reduce prolonged diarrhea >4 days (RR 0.45; 95% CI: 0.32-0.64), very low certainty 1

Lactobacillus rhamnosus GG (ATCC 53103):

• May reduce diarrhea duration by 23.13 hours (95% CI: 12.33-33.94 hours), low certainty 1, 2
• Evaluated in 19 trials, including the negative North American studies 1
• Critical caveat: This is the exact strain that failed in high-quality North American trials 1

Lactobacillus reuteri:

• May reduce diarrhea duration by 24.36 hours (95% CI: 33.55-13.17 hours), low certainty 1, 2
• May reduce prolonged diarrhea >3 days (RR 0.67; 95% CI: 0.47-0.95), low certainty 1

Adult Gastroenteritis

Evidence for adults is extremely limited. 1

• The Cochrane review included 8,014 adults and children combined, but the vast majority were pediatric studies 1
• No specific recommendations exist for adults with acute gastroenteritis 1
• The same geographic considerations likely apply 1

Where Probiotics DO Have a Role in Diarrheal Illness

Antibiotic-Associated Diarrhea:

• Use L. rhamnosus GG or S. boulardii to prevent antibiotic-associated diarrhea 2, 3, 4
• Reduces risk by approximately 50%, moderate-quality evidence 2
• This indication has much stronger evidence than acute gastroenteritis 3, 4, 5

Clostridioides difficile Infection Prevention:

• Probiotics reduce CDI risk by 64% when given with antibiotics, moderate certainty 2
• S. boulardii (1g, 3×10^10 CFU/day) as adjunct may increase diarrhea cessation (RR 1.33; 95% CI: 1.02-1.74) and decrease recurrence (RR 0.59; 95% CI: 0.35-0.98), low certainty 2

Necrotizing Enterocolitis Prevention:

• Use combination probiotics (Lactobacillus + Bifidobacterium species) in preterm infants <37 weeks gestational age 1, 2
• This has moderate-to-high quality evidence and addresses mortality 1, 2

Practical Algorithm for Acute Gastroenteritis

Step 1: Determine patient location

• If in US/Canada → Do not use probiotics 1, 2
• If outside North America → Consider probiotics as adjunct to rehydration 2

Step 2: If outside North America and considering probiotics:

• First choice: S. boulardii (has most trials, though very low certainty) 1, 2, 3, 4, 5
• Alternative: L. rhamnosus GG or L. reuteri DSM 17938 1, 2, 3, 4, 5
• Duration: 5 days 2
• Dose: ≥10^10 CFU/day generally more effective 2

Step 3: Set realistic expectations:

• At best, may shorten diarrhea by approximately 1 day 1, 3, 4
• Does not reduce stool frequency on days 2-3 1
• Does not reduce hospitalization rates 1

Critical Safety Considerations

Avoid probiotics in high-risk populations: 2, 4

• Immunocompromised patients
• Premature neonates (except for NEC prevention with specific strains)
• Patients with central venous catheters
• Critically ill patients
• Cardiac valvular disease
• Short-gut syndrome

Rare invasive infections have been reported in these populations 4

Common Pitfalls to Avoid

1. Do not extrapolate strain efficacy: Benefits of one probiotic strain cannot be assumed for another, even within the same species 6, 5

2. Do not ignore geographic context: The most important determinant of whether to use probiotics is where you practice 1

3. Do not use probiotics as monotherapy: They are only adjuncts to proper rehydration 3, 4, 5

4. Do not continue beyond 5 days for acute gastroenteritis: No evidence supports longer duration 2

5. Do not assume "probiotic" means effective: Most studies showing benefit had significant bias concerns 1