Researchers Determine How to "Starve" Salmonella

It turns out that the picky appetite of the Salmonella bacteria might be its downfall. Researchers have found that Salmonella relies on a very specific nutrient to survive, and blocking the bacteria's access to this nutrient can essentially "starve" the infection.

Salmonellosis, the illness caused by a Salmonella infection, usually lasts four to seven days and despite extreme discomfort, dehydration and violent diarrhea, the illness is not traditionally fatal. Still, according to the US Centers for Disease Control and Prevention (CDC), Salmonella still causes a total of 1.2 million illnesses in the United States a year, with 23,000 hospitalizations and 450 deaths (usually among the already seriously ill).

Despite these numbers, the CDC and most medical experts believe that the best way to treat salmonellosis is to treat its symptoms - mainly dehydration - until a patient outlasts the infection. Professionals would need to use antibiotics to directly attack the bacteria, but these treatments could disrupt an essential balance of gut bacteria in the process - causing more harm than good.

Now, according to a study published in the journal PLOS Pathogens, researchers have found a way to quickly and effectively starve the bacteria, avoiding the infection's potential long-term consequences, such as reactive arthritis.

Researchers stumbled upon this discovery when screening for genes that have to be expressed for Salmonella to survive during gastroenteritis - the phase when immune responses from the gut cause symptoms in an effort to fight the infection.

They discovered five vital genes that work together to transport a very specific nutrient, fructose-asparagine (F-Asn), to the bacterial cells to be consumed for energy.

"For some reason, Salmonella really wants this nutrient, and if it can't get this one, it's in really bad shape," Brian Ahmer, lead author of the study, said in a statement.

What is remarkable about this discovery, explained Ahmer, is that it showed how unique Salmonella is as a picky eater.

"That was one of the big surprises: that there is only one nutrient source that is so important to Salmonella. For most bacteria, if we get rid of one nutrient acquisition system, they continue to grow on other nutrients," he said. "In the gut, Salmonella can obtain hundreds of different nutrients. But without fructose-asparagine, it's really unfit."

The researchers are now looking into inexpensive drugs that could target the transportation of F-Asn to Salmonella cells, also considering the window of time that would be appropriate to treat the already short-lived infection.

The study was published in PLOS Pathogens on June 26.