Salmonella Secrets: How the Bacteria Manipulates Gut Defenses to Cause Infection – New Study Revealed

A new study from UC Davis Health reveals how Salmonella bacteria can invade the gut, even with protective bacteria present. Published in the Proceedings of the National Academy of Sciences, the research explains that Salmonella tricks the gut environment to avoid the body’s defenses.

The digestive system hosts many bacteria. Some produce short-chain fatty acids (SCFAs) that fight harmful germs. However, Salmonella thrives in the gut despite these defense mechanisms. The researchers aimed to understand how Salmonella circumvents this protection.

Lead author Andreas Bäumler, a UC Davis professor, explained that Salmonella primarily replicates in the colon rather than the small intestine. The bacteria cause inflammation in the gut lining, disrupting amino acid absorption from food. This disruption creates a nutrient imbalance that favors Salmonella’s growth in the large intestine, where beneficial bacteria usually limit its spread.

Using a mouse model, the team studied how Salmonella alters the gut’s chemical balance. They found that mice infected with Salmonella absorbed fewer amino acids into the blood. Notably, two amino acids, lysine and ornithine, increased in the gut post-infection. These amino acids helped Salmonella by restoring its acidity (pH), allowing the bacteria to evade the microbiota’s defenses.

Bäumler noted, “Salmonella cleverly changes the gut’s nutrient environment to its advantage.” The research shows how the pathogen can manipulate the gut to create favorable conditions for itself.

The study also revealed Salmonella uses its virulence factors to activate enzymes that break down key amino acids. This action helps it evade the protective effects of SCFAs and thrive in the gut.

These findings could explain changes in the gut environment during inflammatory bowel disorders like Crohn’s disease and ulcerative colitis. They may also lead to improved treatments for gut infections. Understanding how Salmonella modifies the gut could assist in developing new strategies to protect gut microbiota and combat these infections.

Lauren Radlinski, the study’s first author, emphasizes a holistic approach to gut health. She believes the research may inspire new treatments that support the microbiota during infections. Possible treatments include probiotics or dietary plans designed to enhance the body’s defenses against harmful pathogens.

Coauthors of the study include Andrew Rogers, Lalita Bechtold, Hugo Masson, Henry Nguyen, Anaïs B. Larabi, Connor Tiffany, Thaynara Parente de Carvalho, and Renée Tsolis from UC Davis.