Protective effect of Escherichia coli Nissle1917 on Salmonella typhimurium infection by regulating intestinal flora

Salmonella is a global foodborne zoonosis that seriously threatens livestock breeding and human health. Due to the implementation of an ant resistance policy, probiotics as an alternative to antibiotics have attracted widespread attention. In this study, the widely used probiotic Escherichia coli Nissle 1917(EcN) was selected to study its protective effect on mice infected with Salmonella. After mice were treated with EcN, flow cytometry showed that the frequency of mature dendritic cells in the Peyers patch was increased. After Salmonella infection, EcN increased the survival rate of the mice and decreased the degree of pathological changes and the number of live bacteria in the spleen and liver. The results of 16S rRNA high-throughput sequencing of fecal microbial flora showed that EcN could reduce the abundance of microorganisms in the intestine and reduce the proportion of Lactobacillus, while Ruminococcaceae, Rikenella and Bifidobacterium disappeared. In contrast, the abundance of Bacteroides increased, which reduced the effect of Salmonella on the distribution of intestinal microorganisms. Our results demonstrated that EcN has a protective effect against Salmonella infection and may act as a candidate probiotic bacterium to apply in the future.