Scientists identify nutrient that helps prevent bacterial infection

Scientists studying the body’s natural defences against bacterial infection have identified a nutrient named taurine that helps the gut recall prior infections and kill invading bacteria, such as Klebsiella pneumoniae (Kpn). The study was conducted by scientists from five institutes of the US National Institutes of Health (NIH) and could aid efforts seeking alternatives to antibiotics.

Scientists know that microbiota can protect people from bacterial infections, but little is known about how they provide protection. Studies are being conducted on microbiota with an eye to finding or enhancing natural treatments to replace antibiotics, which harm microbiota and become less effective as bacteria develop drug resistance.

The researchers observed that microbiota that had experienced prior infection and transferred to germ-free mice helped prevent infection with Kpn. They identified a class of bacteria called Deltaproteobacteria involved in fighting these infections and further analysis led them to identify taurine as the trigger for Deltaproteobacteria activity.

Taurine helps the body digest fats and oils and is found naturally in bile acids in the gut. The poisonous gas hydrogen sulphide is a by-product of taurine. The scientists believe that low levels of taurine allow pathogens to colonise the gut, but high levels produce enough hydrogen sulphide to prevent colonisation. During the study, the researchers realised that a single mild infection is sufficient to prepare the microbiota to resist subsequent infection and that the liver and gallbladder – which synthesise and store bile acids containing taurine – can develop long-term infection protection.

The study found that taurine given to mice as a supplement in drinking water also prepared the microbiota to prevent bacterial infection. However, when mice drank water containing bismuth subsalicylate – a common over-the-counter drug used to treat diarrhoea and upset stomach – infection protection waned because bismuth inhibits hydrogen sulphide production.

The study was published in the journal Cell.