Bifidobacterium lactis Probio-M8 treated and prevented acute RTI via regulating gut microbiota and metabolites.

The results showed that Probio-M8 treatment although slightly changed the gut microbial structure of the patients, it significantly changed the composition, In-depth metagenomic analysis showed that, at 4-week post-discharge, significantly more species-level genome bins (SGBs) of Bifidobacterium animalis, Corynebacterium pyruviciproducens, Clostridium sp. CAG:58 were increased significantly, while the abundant of Escherichia coli, Streptococcus parasanguinis, Schaalia odontolytica decreased significantly in probiotic group (P<0.05). Furthermore, significantly more microbial bioactive metabolites (e.g., glutamate, N.acetylspermidine, pyridoxamine and alpha-muricholate) but less stearoylethanolamide was detected in the probiotic group than placebo group during/after intervention (P<0.05). Interestingly, we found the relative abundance of Escherichia coli was negatively with IL-10 (r=-0.22, P=0.0022), whereas positively with influenza score (r=0.26, P=0.00024). In addition, alpha-muricholate was negatively with fu-like symptoms and pharyngeal and nasal symptoms score (r=-0.2, P=0.0051; r=-0.2, P=0.0056, respectively). Collectively, our results suggested that administering Probio-M8 may regulate the host inflammatory response by regulating the balance of intestinal microorganisms, bioactive metabolites, and related pathways and bring health-promoting effects to patients with RTIs.