On May 26, 2021, National Institutes of Health (NIH) scientists reported that the immune system’s attempt to eliminate Salmonella bacteria from the gastrointestinal (GI) tract instead facilitates colonization of the intestinal tract and fecal shedding.

Salmonella Typhimurium bacteria (hereafter Salmonella) live in the gut and often cause gastroenteritis in people. The Centers for Disease Control and Prevention estimates Salmonella bacteria cause about 1.35 million infections, 26,500 hospitalizations and 420 deaths in the United States every year. Contaminated food is the source for most of these illnesses. Most people who get ill from Salmonella have diarrhea, fever and stomach cramps but recover without specific treatment. Antibiotics typically are used only to treat people who have severe illness or who are at risk for it.

The scientists hypothesize that, by hijacking the epithelial cell response, Salmonella amplify their ability to invade neighboring cells and seed the intestine for fecal shedding. The researchers say this is an example of how the pressure exerted by the host immune response can drive the evolution of a pathogen, and vice versa. The new insights offer new avenues for developing novel interventions to reduce the burden of this important pathogen.

The study, published in Cell Host & Microbe, was conducted by National Institute of Allergy and Infectious Diseases (NIAID) scientists at Rocky Mountain Laboratories in Hamilton, Montana.