A common gut fungus worsens infection with the food-borne bacterium Salmonella

In an intricate interaction spanning domains of life, the bacterium Salmonella hijacks the yeast Candida to make it produce and release the amino acid arginine in the gut. Arginine increases the virulence of Salmonella and downregulates the host’s immune response to Salmonella infection, leading to more-severe disease. Interactions between the fungus and the bacterium weaken the host’s immune response.