Alkalihalobacillus clausii

Bacillus clausii (current correct nomenclature: Alkalihalobacillus clausii) is a Gram-positive, spore-forming, alkalitolerant rod-shaped bacterium naturally present in the soil and in the mammalian gastrointestinal tract[3][5]. It is used as a probiotic in formulations such as Enterogermina and Erceflora. Due to its unique resistance to gastric acid, bile salts, and many antibiotics, it survives ingestion and colonizes the gut, where it restores microbiota balance, inhibits pathogenic bacteria, and exerts immunomodulatory effects. Clinical studies have demonstrated its efficacy in reducing the duration and severity of acute pediatric diarrhea, antibiotic-associated diarrhea, and as adjunct therapy for Helicobacter pylori infections[2][4][6]. Bacillus clausii is generally well-tolerated but carries risk for bacteraemia/sepsis in immunocompromised individuals; regulatory agencies have issued warnings accordingly[3].

Other names

Bacillus clausiiB. clausii

Competes with pathogenic microorganisms for intestinal colonization. Modifies gut microbiota composition. Secretes antimicrobial substances antagonistic to pathogens (e.g., against Staphylococcus aureus, Clostridioides difficile). Modulates immune response by decreasing pro-inflammatory cytokines (e.g., TNF-α, IL-17, IL-23).