US researchers have found that Salmonella manipulates gut conditions to survive by inhibiting nutrient absorption, aiding its growth and persistence in the digestive tract.
A team of US researchers has found that Salmonella bacteria – a major cause of food poisoning – dodges protective bacteria and gets inside the intestine. According to the World Health Organization (WHO), approximately 600 million people fall ill from unsafe food every year, while 420,000 people die from unsafe food annually.
Salmonella is the most common cause of food poisoning. It can be found in raw eggs, undercooked poultry, beef, pork, vegetables and processed foods. Trillions of bacteria live in the gut and produce many short-chain fatty acids (SCFAs) that help fight harmful pathogens.
Salmonella grows in the intestine by altering the balance of nutrients in the digestive tract. The study, published in the Proceedings of the National Academy of Sciences, showed that it survives by altering the nutritional environment of the stomach.
While it was previously known that Salmonella invades the small intestine, Professor Andreas Baumler of the University of California-Davis, US, said they found that the pathogen can enter the colon and spread.
Salmonella first enters the small intestine and causes inflammation in the lining of the intestine. This disrupts the normal absorption of amino acids from food, creating an imbalance, enabling the pathogen to survive and multiply in the large intestine (colon), Bäumler, who is also lead author, explained.
Inflammation in the small intestine helps Salmonella obtain nutrients, which promotes its replication in the colon, he said.
In mice models, researchers found that Salmonella infection led to reduced absorption of amino acids in the blood. After infection, two amino acids, lysine and ornithine, become more abundant in the intestine and prevent the growth-inhibiting effects of SCFAs. This helps Salmonella to survive.
“Our findings show that Salmonella has a clever way of changing the nutritional environment of the intestine to its advantage. By making it harder for the body to absorb amino acids in the ileum, Salmonella creates a more favorable environment for itself in the large intestine. Is,” Baumler said.
The findings explain how the gut environment changes during inflammatory bowel disorders such as Crohn’s disease and ulcerative colitis, and may lead to better treatments for gut infections.
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