Bacillus clausii

Tier 2 — promising · Probiotic · Antibiotic-associated diarrhoea

A spore-forming probiotic (Enterogermina) used extensively in Europe, India, and Latin America for antibiotic-associated diarrhoea, paediatric diarrhoea, and IBS. Survives simultaneous antibiotic exposure due to intrinsic resistance to common antibiotics — making it uniquely suitable for concurrent use with antibiotics. Multiple RCTs support benefit in children and adults for acute diarrhoea. Naturally antibiotic-resistant strains theoretically raise horizontal-transfer concerns, though no clinical problems have emerged in decades of use.

Dose: 2–6 billion spores daily, taken in 1–3 divided doses with or without food. Often dispensed as 5-mL liquid vials in Europe/India.