Prevention of Escherichia coli O157:H7 infection in gnotobiotic mice associated with Bifidobacterium strains

Abstract

Previous reports have shown that Escherichia coli O157:H7 infection is strongly modified by intestinal microbes. In this paper, we examined whether bifidobacteria protect against E. coli O157:H7 infections using gnotobiotic mice di-associated with Bifidobacterium strains (6 species, 9 strains) and E. coli O157:H7. Seven days after oral administration of each Bifidobacterium strain, the mice were orally infected with E. coli O157:H7 and their mortality was examined. Bifidobacterium longum subsp. infantis 157F-4-1 (B. infantis 157F) and B. longum subsp. longum NCC2705 (B. longum NS) protected against the lethal infection, while mice associated with all other Bifidobacterium strains, including type strains of B. longum subsp. infantis and B. longum subsp. longum, died. There were no significant differences in the numbers of E. coli O157:H7 in the faeces among the Bifidobacterium-associated mouse groups. However, the Shiga toxin concentrations in the cecal contents and sera of the GB mice associated with B. infantis 157F and B. longum NS were significantly lower than those of the other groups. However, there were no significant differences in the volatile fatty acid concentrations and histopathological lesions between these two groups. These data suggest that some strains of B. longum subsp. longum/infantis can protect against the lethal infections of E. coli O157:H7 by preventing Shiga toxin production in the cecum and/or Shiga toxin transfer from the intestinal lumen to the bloodstream.

Probiotic Lactobacillus reuteri Ameliorates Disease Due to Enterohemorrhagic Escherichia coli in Germfree Mice

“…These results are similar to those of published studies demonstrating both colonization suppression and disease protection by other probiotic or nonpathogenic bacterial species, including certain strains of bifidobacteria (2,10,37), lactobacilli (23), clostridia (32), or commensal E. coli (11,19). Colonization density by probiotic bacteria in those studies generally was similar to that of L. reuteri in the current study (2,10,11,19,32,37), although reports ranged from 10 6 to 10 10 CFU/g. The mechanisms whereby probiotics protect mice from disease due to EHEC are not well understood, although several possibilities have been investigated or proposed.…”

“…In addition, several studies noted above have shown that nonpathogenic E. coli (11), Clostridium butyricum (32), or bifidobacteria species (2) suppress Stx levels in vivo. The reduction in Stx2 levels in these models is somewhat difficult to assess, as colonization by EHEC also was affected, but a more-recent study showed that some strains of bifidobacteria can reduce disease and Stx2 production without showing a significant reduction in EHEC colonization (37). Finally, several studies have shown that at least in vitro, probiotics, including lactobacilli, may induce host protection mechanisms such as host inflammatory response, epithelial barrier function, or epithelial survival, thus conferring resistance to disease (16,20).…”

“…Recently, several laboratories have explored the role of probiotic bacteria in the control and treatment of gastrointestinal diseases (20,29), including EHEC (2,5,10,11,14,15,19,23,31,32,37). Probiotic bacteria are live microbes that, when consumed, confer a beneficial effect on the host.…”

Role of rifampicin in limiting Escherichia coli O157:H7 Shiga-like toxin expression and enhancement of survival of infected BALB/c mice

“…Particular Bifidobacterium strains, for example, have shown promising results in reducing the risk of E. coli O157:H7 infection sequelae in mice [29][30][31][32]. Attempts at controlling this agent via vaccination or treatment of cattle, a reservoir in which E. coli O157:H7 is a commensal, had variable success [9].…”

Yogurt Containing Bioactive Molecules Produced by Lactobacillus acidophilus La-5 Exerts a Protective Effect against Enterohemorrhagic Escherichia coli in Mice

“…longum! inf antis and Lactobacillus reuteri also inhibited the effect of Stx (15,66). Previous work by our research group has shown that bioactive molecules produced by Lactoba cillus acidophilus La-5 and Bifidobacterium bifidum reduced the number of EHEC 0157 cells able to attach to GI epithelial cells (4,35).…”