Light micrograph of a normal human colon in the large intestine.

The large intestine. Infection ‘trains’ both the digestive system and the gut microbiome to fend off hostile microorganisms. Credit: Nigel Downer/SPL

Microbiome

A case of ‘stomach flu’ arms the microbiome against invaders

Gut-wrenching infection encourages production of an amino acid consumed by helpful bacteria.

Some intestinal illnesses might be a blessing in disguise. A study in mice shows that bowel infections can help gut-dwelling microbes to fight off pathogens.

Apollo Stacy and Yasmine Belkaid at the National Institutes of Health in Bethesda, Maryland, and their colleagues collected gut microbes from mice that had been infected with the food-borne pathogen Yersinia pseudotuberculosis and from others that hadn’t. The infected animals’ guts had higher levels of compounds that contain the amino acid taurine. Infected mice also had higher levels of gut microbes that consume taurine and convert it into a molecule that can slow pathogen growth.

The authors transferred gut microbes from each group into separate groups of recipient mice. Then they exposed recipients to the bacterium Klebsiella pneumoniae, a human pathogen. Recipients of microbes from mice with a history of Y. pseudotuberculosis infection were better protected from Klebsiella than were recipients of microbes from mice that hadn’t been infected with Y. pseudotuberculosis.

The findings suggest that intestinal infections ‘train’ mice to produce taurine, which favours the growth of taurine-eating, protective gut bacteria.