Role of Bifidobacterium breve PRL2020 in reducing symptoms of antibiotic-associated diarrhea in children

Background: Antibiotic-associated diarrhea (AAD) is a common adverse effect of amoxicillin and amoxicillin/clavulanate therapy in children, primarily driven by antibiotic-induced dysbiosis, altered fermentation, and reduced production of short-chain fatty acids. Probiotics may help prevent AAD, but many strains are inhibited by these antibiotics. The present study specifically addresses the clinical impact of a single probiotic strain, Bifidobacterium breve PRL2020, rather than the intestinal microbiota as a whole. Methods: We conducted a 15-day, prospective, single-center controlled study enrolling children between January 2021 and December 2022, recruited by three Italian pediatricians from the Lombardy region (Northern Italy), to evaluate the efficacy of Bifidobacterium breve PRL2020, a strain with documented resistance to amoxicillin and amoxicillin/clavulanate, in children aged 4-12 years undergoing antibiotic therapy. Parents recorded daily bowel movements, episodes of diarrhea, abdominal pain (VAS), and stool consistency (Bristol scale). Results: Among 426 enrolled children (284 supplemented, 142 controls), supplementation with B. breve PRL2020 significantly reduced the number of diarrheal episodes (p < 0.001) and abdominal pain (p < 0.005) compared with controls, without affecting stool frequency or consistency. Some children experienced mild diarrheal events (<3 episodes/day) not meeting the formal definition of AAD but likely reflecting partial manifestations of AAD-related mechanisms. Conclusions: B. breve PRL2020 was associated with a significant reduction in antibiotic-associated diarrhea and abdominal discomfort in children receiving amoxicillin or amoxicillin/clavulanate. Its antibiotic resistance profile supports its use as a precision probiotic. Accordingly, the observed effects should be interpreted as strain-specific outcomes attributable to PRL2020 supplementation, and not as evidence of a global microbiota-wide modification. Longer-term, multi-omics studies are needed to confirm durability of the effect and to investigate combined probiotic-prebiotic strategies for optimizing gut microbiota resilience.