Protective effects of oral administration of mixed probiotic spores of Bacillus subtilis and Bacillus coagulans on gut microbiota changes and intestinal and liver damage of rats infected with Salmonella Typhimurium

Although the intestinal lumen is a significant way to enter pathogens such as Salmonella, they face a dense microbiota in the gut lumen. This community confers health benefits. Probiotics enhance the colonization resistance and direct inhibition of pathogens, which are essential in reducing the incidence and duration of gastroenteritis and histopathological complications of enteric pathogens. In this study, the spores of two probiotic bacteria, Bacillus subtilis and Bacillus coagulans, were fed to rats for 3 weeks through their daily water intake. After that, Salmonella typhimurium was gavaged to the rats. On days 1, 3, 5, and 7 after gavaging, intestinal microbiota were evaluated, and on days 3, 5, and 7 after gavaging, gut and liver histopathological changes were also evaluated. Salmonella caused no changes in the spore and aerobic bacteria population compared to the control group, but it increased anaerobic and coliform bacteria and reduced lactic acid bacteria (LAB). But B. subtilis and B. coagulans reduced anaerobic and coliform bacteria and decreased the LAB population following Salmonella infection. Also, the histopathological evaluation showed that these probiotics attenuated the shortening and fusion of villi, mononuclear cell infiltration, submucosal edema, and epithelial necrosis in the intestine, hepatocyte degeneration, and mononuclear cell infiltration in the liver, which occurred due to Salmonella infection. B. subtilis and B. coagulans help the maintenance of the gut microflora population and reduce the histopathological effects when exposed to Salmonella, which causes the reduction of these pathogen's effects and early recovery. Protective effects of probiotic spores on intestinal and liver damage of rats infected with Salmonella Typhimurium