Lactobacillus Rhamnosus GG: Does It Prevent Pneumonia in ICU Patients?

clinical-trial PMID: 34546300

Lactobacillus Rhamnosus GG: Does It Prevent Pneumonia in ICU Patients?

Quick Summary: A large clinical trial tested if the probiotic Lactobacillus rhamnosus GG could stop ventilator-associated pneumonia (VAP) in seriously ill ICU patients on breathing machines. The study found no benefit in preventing VAP or other infections compared to a placebo, and it even raised some safety concerns. This suggests probiotics like this one may not help in critical care settings.

What The Research Found

Researchers wanted to see if Lactobacillus rhamnosus GG—a common "good" bacteria found in some yogurts and supplements—could protect ICU patients from getting pneumonia while on ventilators. Ventilator-associated pneumonia happens when harmful bacteria build up in the lungs of patients using breathing machines for a long time.

Key results showed:
- No real difference in VAP rates: About 22% of patients on the probiotic got VAP, compared to 21% on placebo (a fake treatment). This tiny gap (0.6%) wasn't meaningful.
- No improvements in other issues: The probiotic didn't cut down on diarrhea, other infections like C. difficile, antibiotic use, hospital stay length, or death rates.
- Potential risks: The probiotic group had a higher chance of the bacteria showing up in places it shouldn't, like blood or wounds—15 cases versus just 1 in the placebo group. This made infections 14 times more likely in those spots.

In short, Lactobacillus rhamnosus GG didn't prevent infections and might add risks for very sick patients.

Study Details

This was a big, reliable test called a randomized clinical trial, where patients were split evenly into groups by chance to get either the real treatment or a look-alike placebo. It ran in 44 ICUs across Canada, the US, and Saudi Arabia from 2013 to 2019.

Who was studied: Over 2,650 adults in critical condition, mostly around age 60, who needed breathing machines (mechanical ventilation) for at least 3 days. They were very sick, with average health scores showing high risk.
How long: Patients got the treatment for a median of 9 days (ranging from 5 to 15 days) while in the ICU, with follow-up until October 2020.
What they took: A high dose of Lactobacillus rhamnosus GG—about 10 billion live bacteria—given by tube into the stomach twice a day. The placebo group got an inactive version.

Doctors checked for VAP using strict, blind reviews to ensure fair results.

What This Means For You

If you're healthy or just dealing with gut issues, this study doesn't change much—probiotics like Lactobacillus rhamnosus GG are still popular for everyday digestion or mild infections, and many people use them safely in foods or supplements. But if you or a loved one ends up in the ICU on a ventilator, this research says skip this specific probiotic for preventing pneumonia; it won't help and could cause problems.

Talk to your doctor before trying probiotics during serious illness. For general wellness, look for evidence-based uses, like supporting gut health after antibiotics. Always choose reputable brands to avoid contamination risks.

Study Limitations

No study is perfect, and this one has a few caveats to keep in mind:
- It focused only on very sick ICU patients needing long-term ventilation—results might not apply to milder cases or other groups, like kids or outpatients.
- The trial stopped early because early results showed no benefit, which might mean it couldn't spot very small effects.
- Safety issues were rare but real; not every probiotic strain behaves the same, so other types might differ.
- It tested one specific dose and way of giving it (through a tube), so yogurt or pills might act differently.

Overall, this highlights the need for more research on probiotics in hospitals before recommending them widely.

Key Findings

The study found that administering Lactobacillus rhamnosus GG (1 × 10¹⁰ CFU twice daily) to critically ill patients on mechanical ventilation did not significantly reduce the incidence of ventilator-associated pneumonia (VAP) compared to placebo (21.9% vs. 21.3%; hazard ratio [HR], 1.03; 95% CI, 0.87–1.22; P = 0.73). No differences were observed in secondary outcomes, including ICU-acquired infections, diarrhea, antimicrobial use, mortality, or length of stay. However, the probiotic group had a higher risk of adverse events involving L. rhamnosus in sterile/nonsterile sites (1.1% vs. 0.1%; odds ratio [OR], 14.02; 95% CI, 1.79–109.58; P < 0.001).

Study Design

This was a multicenter, randomized, placebo-controlled clinical trial conducted across 44 ICUs in Canada, the U.S., and Saudi Arabia. It enrolled 2,653 adults predicted to require mechanical ventilation for ≥72 hours. Patients were followed from October 2013 to March 2019 (final follow-up October 2020). The primary outcome was adjudicated VAP incidence, with 20 prespecified secondary outcomes.

Dosage & Administration

Participants received 1 × 10¹⁰ colony-forming units (CFU) of L. rhamnosus GG or placebo enterally twice daily during their ICU stay. The median duration of administration was 9 days (IQR, 5–15 days).

Results & Efficacy

VAP Incidence: No significant difference between probiotic (289/1318, 21.9%) and placebo (284/1332, 21.3%) groups (HR, 1.03; 95% CI, 0.87–1.22; P = 0.73; absolute difference: 0.6%, 95% CI, -2.5% to 3.7%).
Secondary Outcomes: No significant effects on ICU-acquired infections (e.g., C. difficile), diarrhea, antimicrobial use, ICU/hospital length of stay, or mortality.
Adverse Events: L. rhamnosus GG was associated with a 14-fold higher risk of isolation in sterile/nonsterile sites (15 vs. 1 patients; OR, 14.02; P < 0.001).

Limitations

Early Termination: The trial was stopped for futility after enrolling 2,653 patients, potentially limiting statistical power to detect smaller effects.
Population Specificity: Results apply only to critically ill patients requiring prolonged ventilation, not to other populations or probiotic strains.
Adjudication Rigor: While VAP was centrally adjudicated, reliance on clinical criteria and cultures may miss subclinical cases.
Generalizability: Findings may not extend to probiotics with different dosages, strains, or administration routes.

Clinical Relevance

For critically ill patients, this study does not support the use of L. rhamnosus GG to prevent VAP or other ICU-related infections. The observed increase in probiotic-associated adverse events raises safety concerns in this vulnerable population. Clinicians should weigh potential risks against unproven benefits when considering probiotics for ICU patients. Future research may explore strain-specific effects or alternative microbiome-targeted therapies.

Takeaway: In mechanically ventilated ICU patients, L. rhamnosus GG neither prevents pneumonia nor improves clinical outcomes but may increase infection risks.