Probiotics for Kids on Antibiotics: Diarrhea Study

clinical-trial PMID: 35727573

Probiotics for Kids on Antibiotics: Diarrhea Study

Quick Summary: A clinical trial tested a multispecies probiotic blend including Lactobacillus acidophilus to see if it prevents diarrhea in children taking antibiotics. The probiotic didn't significantly cut the risk of strict antibiotic-associated diarrhea, but it did lower the overall chance of any diarrhea during and after treatment. This suggests it might help with general gut upset from antibiotics, though results depend on how diarrhea is defined.

What The Research Found

This study looked at whether a probiotic mix with Lactobacillus acidophilus and other helpful bacteria could stop diarrhea caused by antibiotics in kids. Here's what they discovered in simple terms:

No big win against strict antibiotic-associated diarrhea (AAD): About 14% of kids on the probiotic got AAD (defined as 3+ loose stools a day, possibly from C. difficile bacteria or unexplained causes), compared to 17% on placebo. The difference wasn't statistically significant (relative risk 0.81; 95% CI 0.49-1.33), meaning it might not reliably prevent this specific type.
Lower risk of any diarrhea: The probiotic reduced the overall chance of diarrhea from any cause by 35% (22% in probiotic group vs. 34% in placebo; relative risk 0.65; 95% CI 0.44-0.94). This includes gut issues not just tied to antibiotics.
Other results: No differences in how long diarrhea lasted or serious complications. Side effects were similar in both groups, so the probiotic was safe.
Key insight: How you define AAD matters a lot—stricter rules (like including C. difficile tests) made the probiotic seem less effective, but it still helped broadly with antibiotic-related tummy troubles.

Lactobacillus acidophilus (strains W37 and W55) was part of an 8-strain blend, but the study couldn't pinpoint its solo role due to the mix.

Study Details

Who was studied: 350 children (192 boys, 158 girls) aged 3 months to 18 years (average 4 years old), both in hospitals and at home. They started broad-spectrum antibiotics for various reasons and joined within 24 hours.
How long: Treatment lasted as long as their antibiotics, plus 7 extra days. The full study ran from February 2018 to May 2021, with follow-up during that time.
What they took: Kids got a daily dose of 10 billion colony-forming units (CFU) of the probiotic mix in capsules or liquid, depending on age. It included Lactobacillus acidophilus plus Bifidobacterium bifidum, Bifidobacterium lactis, Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, and Ligilactobacillus salivarius. The placebo group got fake versions that looked and tasted the same. It was a randomized, quadruple-blind trial (neither kids, parents, doctors, nor researchers knew who got what).

Of the 350 kids, 313 completed the analysis.

What This Means For You

If your child needs antibiotics, this study shows a multispecies probiotic with Lactobacillus acidophilus might not fully prevent severe antibiotic-associated diarrhea, but it could ease overall diarrhea risks—like fewer upset stomachs from the meds disrupting good gut bacteria.

For parents: Talk to your pediatrician about probiotics during antibiotic courses, especially for kids prone to tummy issues. This blend was safe, so it might be worth trying for general protection, but don't rely on it alone for C. difficile risks.
Everyday tip: Probiotics work best as "good bacteria" boosters—pair with a balanced diet and hydration to support gut health. If diarrhea hits, watch for signs like dehydration and seek medical help.
Bottom line: It highlights that not all probiotics are miracle cures; effects vary by what's causing the diarrhea. For antibiotic use in kids, this could mean fewer sick days from loose stools.

Study Limitations

No study is perfect, and this one had a few hurdles that could affect the results:

Smaller group than planned: They aimed for more kids but stopped early due to slow sign-ups (only 350 out of 646 possible), which might make findings less reliable.
Mixed settings: Kids were from hospitals and home, so differences in diets, antibiotic types, or care could influence outcomes.
Strict AAD rules: The definition included tough-to-prove cases (like unexplained or C. difficile), which might hide the probiotic's benefits for milder issues.
Team effort, not solo star: The probiotic was a blend, so we can't say Lactobacillus acidophilus alone did the work—other strains might share credit or cause interactions.

Overall, more research is needed for clearer guidelines on probiotics for kids' antibiotic side effects. Always check with a doctor before starting supplements.

Key Findings

This trial found that a multispecies probiotic containing Lactobacillus acidophilus (strains W37 and W55) did not significantly reduce the risk of antibiotic-associated diarrhea (AAD) (RR 0.81; 95% CI 0.49–1.33) in children. However, it did lower the risk of diarrhea of any etiology (RR 0.65; 95% CI 0.44–0.94). The study highlights how varying definitions of AAD (e.g., including Clostridioides difficile or unexplained cases) can influence trial outcomes, suggesting probiotics may broadly mitigate diarrhea but not strictly AAD in pediatric populations.

Study Design

A randomized, quadruple-blind, placebo-controlled clinical trial conducted across mixed inpatient/outpatient settings (February 2018–May 2021). 350 children (192 boys, 158 girls; mean age 50 months [range: 3–212 months]) were enrolled, with 313 included in the intention-to-treat analysis. Participants received interventions within 24 hours of starting broad-spectrum antibiotics and were followed for the duration of antibiotic treatment plus 7 days post-treatment.

Dosage & Administration

The probiotic formulation included two strains of Lactobacillus acidophilus (W37 and W55) alongside six other bacterial strains, totaling 10 billion colony-forming units (CFU)/day. Administered as capsules or suspensions based on age, the intervention was delivered daily during antibiotic treatment and for 7 days afterward. Placebo groups received identical-appearing inert capsules/suspensions.

Results & Efficacy

Primary outcome (AAD): No significant difference between probiotic and placebo groups (14.0% vs. 17.4%; RR 0.81; 95% CI 0.49–1.33; p > 0.05).
Secondary outcome (all-cause diarrhea): Probiotic reduced diarrhea incidence (22.2% vs. 34.2%; RR 0.65; 95% CI 0.44–0.94).
Other secondary outcomes (diarrhea duration, complications) showed no significant differences. Adverse events were comparable between groups.

Limitations

Early trial termination due to slow recruitment (target: 646 approached, 350 enrolled), potentially reducing statistical power.
Mixed population: Combined inpatient and outpatient settings may introduce variability in antibiotic types, diets, or other confounders.
Broad AAD definition: Inclusion of both C. difficile-positive and unexplained diarrhea cases might dilute strain-specific effects.
Multispecies formulation: Effects cannot be attributed to L. acidophilus alone, as interactions among strains may influence outcomes.

Clinical Relevance

While this specific probiotic blend failed to prevent AAD in children, it reduced the overall risk of diarrhea during and after antibiotic use. Clinicians should consider that probiotic efficacy may depend on diarrhea etiology and that broader definitions of AAD could mask true effects. The formulation’s safety profile aligns with placebo, supporting its use in pediatric populations where general diarrhea prevention is a priority. However, targeted AAD prevention may require higher doses, different strains, or longer post-antibiotic administration.

Takeaway: This study does not support the use of this multispecies probiotic for preventing C. difficile-linked or strictly defined AAD in children but suggests potential for reducing unexplained antibiotic-related diarrhea.