Bacillus species, particularly Bacillus clausii, have been studied for their role as probiotics in the prevention and treatment of enteritis, especially in the context of antibiotic-associated diarrhea and infectious diarrhea, including in children. The evidence supporting their use is primarily scientific, although the depth and quality of evidence vary depending on the specific strain and the clinical context.

Several randomized controlled trials and meta-analyses indicate that Bacillus clausii can reduce the duration and severity of diarrhea in children with acute gastroenteritis and can help prevent antibiotic-associated diarrhea. The proposed mechanisms of action include modulation of gut microbiota, competitive inhibition of pathogenic bacteria, enhancement of mucosal barrier function, and immunomodulatory effects. Bacillus subtilis and Bacillus coagulans have also been investigated as probiotics, with some clinical studies suggesting potential benefits for gastrointestinal health, though evidence for their efficacy in treating enteritis specifically is less robust compared to Bacillus clausii.

Overall, while there is moderate scientific support for the use of certain Bacillus strains in managing enteritis, particularly in pediatric populations and in the context of antibiotic use, the strength of the evidence is not as high as for some other probiotic species (e.g., Lactobacillus or Saccharomyces boulardii). The rating of 3 reflects moderate, but not conclusive, evidence from clinical trials and meta-analyses.