Study: alcohol-producing bacteria causes liver disease in non-drinkers

Chinese researchers have found that a type of bacteria can produce large amounts of alcohol in the gut, high enough to cause liver disease in non-drinkers.

Non-alcoholic fatty liver disease (NAFLD), in which fat builds up in the liver due to factors other than alcohol, affects around a quarter of the adult population in the world. Its cause remains unknown.

According to researchers from the Capital Institute of Pediatrics, Wuhan Institute of Virology under the Chinese Academy of Sciences, and other Chinese research institutions, they came across the bacteria when they were treating a NAFLD patient with severe liver damage and auto-brewery syndrome (ABS), a rare condition where people become intoxicated after eating sugary and starchy foods.

Previous studies found that the ABS could be related to a yeast infection. Yeast can ferment alcohol in the gut as it brews beer in a barrel.

In the new study, the researchers found that the case of ABS was due to bacteria.

In the patient’s feces, several strains of Klebsiella pneumonia (K. pneumonia), a common type of commensal gut bacteria, were found to produce alcohol four to six times higher than strains found in healthy people.

The researchers then analyzed gut bacteria samples from 43 NAFLD patients and 48 healthy people. The results showed about 60 percent of NAFLD patients had medium to high levels of K. pneumonia in the gut while only 6 percent of healthy volunteers carried the bacteria.

In the following studies, germ-free mice were fed K. pneumonia isolated from the ABS patient for three months. Fat started to build up in the liver after the first month. After two months, the mice livers showed signs of fibrosis, scarring that indicates long-term liver damage.

Meanwhile, the researchers found that the progression of fatty liver disease in the mice was comparable to those mice that were fed alcohol.

When the bacteria-fed mice were given antibiotics that kill K. pneumonia, their liver conditions were reversed.

The findings have been reported in the journal Cell Metabolism.

The researchers said their findings hold potential for use in the diagnosis and treatment of bacteria-related NAFLD as patients carrying the high-alcohol-producing K. pneumonia have a more detectable level of alcohol in the blood after drinking a glucose solution.

In future studies, they plan to find out what makes some people more susceptible to the high-alcohol producing strains of K. pneumonia.