Efficacy and safety of spore-forming probiotics in diarrhea management

Background. Diarrheal syndrome remains one of the most common reasons for seeking medical care and a significant cause of morbidity in both children and adults. The cornerstone of treatment includes rehydration therapy and correction of fluid and electrolyte imbalances; however, probiotics are widely used as adjunctive agents in comprehensive management. Conventional probiotic microorganisms, such as representatives of the genera Lactobacillus and Bifidobacterium, may be susceptible to gastric acidity, bile acids, and digestive enzymes, which can limit their survival and, consequently, their potential clinical efficacy following oral administration.

Results. In this context, spore-forming probiotics are of particular interest due to their increased resistance to the aggressive conditions of the gastrointestinal tract. Spores of bacteria from the genus Bacillus are capable of surviving passage through the stomach and subsequently germinating in the intestine, thereby enabling a more predictable delivery of active cells to the site of action. Among sporeforming probiotics, Bacillus clausii is the most extensively studied. Experimental data indicate its antimicrobial, immunomodulatory, and anti-inflammatory properties, as well as its ability to inhibit the effects of toxins produced by certain intestinal pathogens and to modulate gut microbiota composition. Clinical evidence, including randomized controlled trials, observational studies, and metaanalyses, suggests the potential efficacy of B. clausii as adjunctive therapy in acute diarrhea in both children and adults, in reducing the risk of antibiotic-associated diarrhea, and in decreasing adverse events during Helicobacter pylori (Н. pylori) eradication therapy. Several studies have reported a reduction in the duration and severity of diarrhea; however, the level of evidence for some indications remains limited and requires further clarification. The safety profile of B. clausii-containing preparations is generally considered favorable. In most clinical studies, adverse events were rare, predominantly mild, and did not necessitate treatment discontinuation. Isolated cases of invasive infections associated with probiotic use, including B. clausii, have been reported, primarily in patients with risk factors such as immunocompromised status, prematurity, or the presence of intravascular catheters. According to systematic reviews, the proportion of B. clausii-related invasive complications is low, and the overall risk of bacteremia and/or sepsis associated with its use appears to be low and comparable to or lower than that observed with several other probiotic microorganisms.

Conclusion. Thus, spore-forming probiotics, particularly Bacillus clausii, represent a promising option in the adjunctive management of diarrheal syndrome due to their enhanced survivability, potential clinical efficacy, and favorable safety profile. Nevertheless, further large, well-designed studies are needed to more clearly define their role in clinical practice, including indications, optimal dosing regimens, and safety criteria, especially in vulnerable patient populations.

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