Probiotic modulation of gut microbiota with Bifidobacterium animalis subsp. lactis XLTG11 and Lactobacillus plantarum CCFM8661 mitigates recurrent respiratory infections in children: a randomised-controlled trial.

Abstract

Recurrent respiratory tract infections (RRTIs) in children are associated with substantial morbidity and healthcare burden. Modulation of the gut microbiota via probiotics represents a potential adjunctive strategy to prevent recurrent infections. This study evaluated the efficacy and safety of Bifidobacterium animalis subsp. lactis XLTG11 and Lactobacillus plantarum CCFM8661 in children with RRTIs. In a double-blind, randomized, placebo-controlled trial, 120 children with RRTIs received either daily probiotic supplementation (1 × 10¹⁰ CFU/day; n = 60) or placebo (n = 60) for 3 months, with a 6-month follow-up. Primary outcome was clinical efficacy; secondary outcomes included gut microbiota composition (16 S rRNA sequencing) and plasma immune biomarkers (IgA, IgG, IgM, C3, C4). Probiotics significantly improved clinical efficacy compared with placebo in both per-protocol [82.1% vs. 64.2%, p = 0.033] and intention-to-treat analyses [76.7% vs. 56.7%, p = 0.020]. Children in the probiotic group experienced fewer and shorter respiratory episodes, including fever, cough, and pharyngeal congestion (all p < 0.05). Probiotic supplementation increased beneficial taxa (B. breve, L. plantarum, S. salivarius, W. cetiin) and reduced potentially pathogenic taxa (Anaerostipes, Vibrio). IgG and IgM levels remained stable or decreased in the probiotic group, contrasting with increases in the placebo group, indicating a balanced humoral response. No adverse events were reported. Daily administration of XLTG11 and CCFM8661 for three months is safe and improves clinical outcomes in children with RRTIs, reducing new respiratory episodes and modulating gut microbiota and immune function. These findings support strain-specific probiotics as a viable adjunctive therapy in pediatric respiratory infections.