Effect of Saccharomyces boulardii against experimental oral infection with Salmonella typhimurium and Shigella flexneri in conventional and gnotobiotic mice

Abstract

Saccharomyces boulardii was shown to be capable of inhibiting multiplication of enteropathogenic bacteria in vitro and is currently used for its anti-diarrhoea properties. We studied the capacity of this yeast to antagonize Salmonella typhimurium and Shigella flexneri in the intestinal tract of conventional or gnotobiotic NMRI mice. Conventional animals were given daily 10 mg doses of S. boulardii, whereas germ-free animals were given a single 10 mg dose. Both groups were challenged orally 5 d later with the pathogenic bacteria (10(8) or 10(2) viable cells, respectively). Control groups were treated with saline instead of S. boulardii. Mortality and/or histopathological data showed a protective effect against the pathogenic bacteria in yeast-treated mice. Saccharomyces boulardii colonized the digestive tract of gnotobiotic mice and the number of viable cells ranged around 10(10) g-1 of faeces. In experimental and control gnotobiotic animals, Salm. typhimurium and Sh. flexneri became rapidly established at a level of about 10(10) viable cells g-1 of faeces and remained at high levels until the animals died or were sacrificed. The protection against Salm. typhimurium and Sh. flexneri obtained in conventional and/or gnotobiotic mice previously associated with S. boulardii is not due to the reduction of the bacterial populations in the intestines.

Protection by Lactobacillus acidophilus UFV-H2B20 against experimental oral infection with Salmonella enterica subsp. enterica Ser. Typhimurium in gnotobiotic and conventional mice

“…However, inhibition of this pathogenic bacteria could occur in higher regions of the digestive tract than colon such as in the small intestine. Similar results were observed with S. boulardii and B. longum (9,11). Various other properties could explain the protective effect of Lactobacillus against enteropathogenic bacteria such as the competition for adhesion sites in the presence of the probiotic and/or the previously demonstrated stimulation of a host nonspecific immune response (7).…”

“…As expected and observed with other probiotics (9,11), the protection offered by L. acidophilus UFV-H2B20 against the pathogenic challenge was higher in conventional than in gnotobiotic mice due to the complementary protective mechanisms from the normal intestinal microbiota and from the biotherapeutic agent present in the first animal model. The protection observed above, was not due to the reduction of the Salmonella populations in the feces as shown in Fig.…”

“…Like other probiotics, such as Saccharomyces boulardii and Bifidobacterium longum (9,11), L. acidophilus UFV-H2B20 is drastically eliminated from the digestive tract of mammals harbouring a complex intestinal microbiota and for this reason daily ingestion of these microorganisms is necessary to maintain high artificial levels in the gastrointestinal tract of conventional mice. On the other hand, its implantation was possible in germfree animals using a single dose.…”

Probióticos e resposta imune

“…Probióticos preparados com essa levedura protegeram camundongos das toxinas de Clostridium difficile (CORTHIER et al, 1992), e camundongos convencionais e gnotobióticos contra infecções por Salmonella typhimurium e Shigella flexneri (RODRIGUES et al, 1996). Sua administração aumentou significativamente as concentrações de IgA intestinal em ratos (BUTS et al, 1990), assim como de antitoxina A de C. difficile na IgA intestinal (QAMAR et al, 2001).…”

Effect of the Escherichia coli EMO strain on experimental infection by Salmonella enterica serovar Typhimurium in gnotobiotic mice

“…Rodrigues et al (8) and Silva et al (9) have demonstrated protection against a challenge with Salmonella enterica subsp. enterica serovar Typhimurium when conventional and gnotobiotic mice were respectively inoculated with Saccharomyces boulardii or Bifidobacterium lactis.…”