Bifidobacterium breve PRL2020 mitigates antibiotic-induced gut symptoms and dysbiosis in children treated with amoxicillin or amoxicillin-clavulanate.

Diarrhea caused by amoxicillin (A) or amoxicillin-clavulanate (AC) is common in children, and the induced dysbiosis is often characterized by a severe reduction in bifidobacteria. However, bifidobacteria are extremely antibiotic-sensitive, and their co-administration with antibiotics is likely unwise. The B. breve PRL2020 strain is an A- and AC-resistant probiotic. In a multicenter, randomized, controlled, non-profit study, we tested the tolerability and efficacy of the PRL2020 strain when co-administered to children (3-12 years; N = 121) undergoing A or AC therapy, attempting to interpret the results obtained by observing the intestinal microbiota in a subgroup (N = 41) of enrolled children. In children treated with the probiotic, the therapy was well tolerated and the incidence of diarrhea was significantly reduced by approximately 70% (p < 0.01). Considering only children with diarrhea, in the probiotic-treated group the onset was postponed by about 15 h, and the symptom lasted 19 h less. Gut microbiota richness was significantly reduced in both groups, without significant differences between probiotic-treated and control children. At the phylum level, antibiotic treatment was associated with an increase in Proteobacteria and a reduction in Actinobacteria, with larger apparent shifts in the control group. Bifidobacteria, particularly B. breve, decreased in controls and increased in treated subjects (p < 0.05), despite not being among the most abundant taxa contributing to the majority of the microbial community. Finally, although only in a trend-based manner, butyrate-producing bacteria decreased less in probiotic-treated children, whereas an increase in succinate-consuming bacteria was observed in controls. Co-administering the B. breve PRL2020 strain with A or AC in children significantly reduces diarrheal symptoms and antibiotic-related dysbiotic status. New blinded, placebo-controlled studies with a more robust sample size for microbiota analysis will have to confirm our data.