Newly identified nutrients help the gut remember previous infections and kill invasive bacteria

Scientists studying the body’s natural defenses against bacterial infection have identified a nutrient – taurine – that helps the gut remember previous infections and kill invasive bacteria, such as Klebsiella pneumoniae (Kpn). The finding, published in the journal Cell by scientists from five institutes at the National Institutes of Health, could help efforts to find alternatives to antibiotics.

Scientists know that the microbiota (the trillions of beneficial microbes that live harmoniously inside our gut) can protect people from bacterial infections, but little is known about how they provide protection. Scientists are studying the microbiota with the goal of finding or improving natural treatments to replace antibiotics, which harm the microbiota and become less effective as bacteria develop drug resistance.

The scientists observed that the microbiota that had experienced a previous infection and had been transferred to germ-free mice helped prevent infection with Kpn. They identified a class of bacteria.Deltaproteobacteris– participated in the fight against these infections and a subsequent analysis led them to identify taurine as a trigger Deltaproteobacteris activity.

Taurine helps the body digest fats and oils and is found naturally in the bile acids of the gut. Hydrogen sulfide poison gas is a by-product of taurine. Scientists believe that low taurine levels allow pathogens to colonize the gut, but high levels produce enough hydrogen sulfide to prevent colonization. During the study, the researchers realized that a single mild infection is enough to prepare the microbiota to resist subsequent infection and that the liver and gallbladder, which synthesize and store taurine-containing bile acids, can develop protection against long-term infection.

The study found that taurine given to mice as a supplement in drinking water also prepared the microbiota to prevent infection. However, when mice drank water containing bismuth subsalicylate, an over-the-counter drug used to treat diarrhea and upset stomach, protection against infection decreased because bismuth inhibits the production of sulfur d ‘hydrogen.

Scientists from NIH’s National Institute of Allergies and Infectious Diseases led the project in collaboration with researchers from the National Institute of General Medical Sciences; the National Cancer Institute; the National Institute of Diabetes and Digestive and Renal Diseases; and the National Human Genome Research Institute.