Abstract:The purpose of the experiment was to explore the effect of Lactobacilus plantarum P9 on the intestinal flora of mice treated with ceftriaxone sodium.The experiment modeled the intestinal flora imbalance in mice after antibiotic treatment and then administered different doses of Lactobacillus plantarum P9 powder.The levels of inflammatory cytokines in the serum were analyzed using enzyme-linked immunosorbent assays.The antioxidant index in the liver and small intestine were identified using visible spectrophotometry.Bacterial counting and 16S rDNA high-throughput sequencing investigated any changes in the intestinal flora of the mice.The results revealed Lactobacillus plantarum P9 can reduce the inflammatory responses to antibiotics and suppress the oxidative stress in organs.Flora counts revealed Lactobacillus plantarum P9 could increase the number of Bifidobacteria and Lactobacillus，limiting the decrease caused by antibiotic use.The 16S rDNA sequencing showed an increase in the abundance of antibiotic-resistant bacteria in the antibiotic treated mice intestines，adding Lactobacillus plantarum P9 reduced the prevalence of drug-resistant bacteria.In summary，Lactobacillus plantarum P9 effectively regulates mice intestinal flora.