Probiotic E. coli may relieve Salmonella infections

A probiotic strain of E. coli which is used to treat irritable bowel syndrome can soothe gut bacterial infections caused by Salmonella, paving the way for potential relief from foodborne illnesses that affect millions of people annually.

Manuela Raffatellu, assistant professor of microbiology & molecular genetics, and colleagues at UC Irvine and the University of Washington identified how a probiotic strain of E. coli reduces Salmonella colonisation by competing with this pathogen for iron, an essential nutrient that Salmonella acquires in the gut in order to replicate at high levels.

In fact, the researchers discovered that the E. coli strain called Nissle 1917 acquires iron more efficiently than does Salmonella. As a result, Salmonella counts in the gut decrease when Nissle is administered during infection. The study has been published in Cell Host & Microbe.

“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.”

Most people infected with Salmonella develop diarrhoea, fever and abdominal cramps 24 to 72 hours after infection. The illness usually lasts four to seven days, and the majority of affected individuals recover without treatment. According to the Centers for Disease Control & Prevention, about 42,000 cases of Salmonellosis are reported annually in the US. Because many milder cases are not diagnosed or reported, the actual number of infections is estimated to be between 1 million and 4 million per year.

For nearly a century, the E. coli Nissle 1917 strain has been administered to patients with a variety of bowel disorders, but little has been known about how this probiotic bacterium works.