E.coli strain hoards iron to nullify salmonella

Salmonella competes with E.coli for iron. Illustration by Janet Liu
Salmonella competes with E.coli for iron. Illustration by Janet Liu

Related tags E. coli Bacteria Salmonella

A probiotic strain of E.coli can reduce the severity of salmonella infections by hoarding iron, according to US researchers.

UC Irvine microbiologists found that the E.coli used to treat irritable bowel syndrome can soothe gut bacterial infections caused by salmonella which could lead to potential relief from foodborne illnesses.

Manuela Raffatellu, assistant professor of microbiology and molecular genetics, and colleagues at UC Irvine and the University of Washington identified how the E. coli reduces salmonella colonization by competing for iron, which is an essential nutrient salmonella acquires in the gut to replicate at high levels.

Iron acquisition

The researchers discovered that the E. coli strain, called Nissle 1917, acquires iron more efficiently than salmonella Typhimurium so counts in the gut decrease when Nissle is administered during infection.

E. coli Nissle overcomes lipocalin 2-mediated iron sequestration and E. coli Nissle outcompetes salmonella for iron in the inflamed gut, said Raffatellu et al.

Altogether, our results show that iron acquisition in the inflamed gut is a critical mechanism for the ability of the probiotic E. coli Nissle to limit salmonella intestinal colonization.

“Furthermore, we have demonstrated that this action of E. coli Nissle results from its resistance to lipocalin 2, previously considered a mechanism of virulence but now also seen as an essential property of a protective commensal organism.

“As antibiotic treatment is contraindicated for uncomplicated salmonella infections due to the prolongation of fecal shedding, the administration of E. coli Nissle may be a feasible alternative for diminishing salmonella colonization and ameliorating symptoms.”

Gaining nutrients

Nissle 1917 is an ingredient in a German probiotic product but is currently unavailable in the US market, said the researchers.

"Although we focused on salmonella, our findings suggest that this approach can be effective against other gut bacterial pathogens that need iron to grow," ​said Raffatellu, who's also a member of UC Irvine's Institute for Immunology.

"By understanding how these 'bad bugs' get nutrients, we can further study methods to eradicate them."

Source: Cell Host and Microbe, volume 14 issue 1 Pages 26-37

Online ahead of print doi: 10.1016/j.chom.2013.06.007

“Probiotic Bacteria Reduce Salmonella Typhimurium Intestinal Colonization by Competing for Iron”

Authors:  Elisa Deriu, Janet Z. Liu, Milad Pezeshki, Robert A. Edwards, Roxanna J. Ochoa, Heidi Contreras, Stephen J. Libby, Ferric C. Fang, Manuela Raffatellu

Related topics Food Safety & Quality

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