A newly identified nutrient helps the gut remember previous infections and kill invading bacteria

Scientists studying the body’s natural defense against bacterial infections have identified a nutrient – taurine – that helps the gut remember previous infections and destroy invading bacteria, such as Klebsiella pneumoniae (Kpn). The finding, published in the journal Cell by scientists from five institutes of the National Institutes of Health, could help efforts looking for 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 it provides protection. Scientists are studying the microbiota in order to find or improve natural treatments to replace antibiotics, which damage the microbiota and become less effective as bacteria develop drug resistance.

Scientists have observed that the microbiota that experienced a previous infection and was transferred to germ-free mice helped prevent infection with Kpn. They identified a class of bacteria …Delta protobacteria– were involved in the fight against these infections, and subsequent analysis led them to identify taurine as a trigger Delta protobacteria activity.

Taurine helps the body digest fats and oils and is found naturally in bile acids in the gut. Poisonous hydrogen sulfide gas is a by-product of taurine. Scientists believe that low levels of taurine 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 withstand subsequent infection and that the liver and gallbladder – which synthesize and store taurine-containing bile acids – can develop long-term protection against infections.

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 – a prescription drug used to treat diarrhea and upset stomach – protection against infections decreased because bismuth inhibits hydrogen sulfide production.

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