Study Reveals Bacteria Behind Auto-Brewery Syndrome
A comprehensive study suggests that bacteria, rather than fungi, are primarily responsible for auto-brewery syndrome (ABS), a rare condition where individuals experience intoxication after eating without consuming alcohol. Researchers examined stool samples from 22 ABS patients and their unaffected household partners, uncovering two bacterial species that were notably prevalent in patients with the syndrome. This aligns with findings from a previous study conducted in 2019.
Diagnosing ABS is quite rare, and treatment options remain unclear. Even though this research involved a small group, it represents a significant number of patients subjected to detailed testing, showing that their gut bacteria can produce high levels of ethanol in laboratory settings.
“Many patients navigate several medical facilities only to be labeled as secret drinkers, ultimately leaving without a diagnosis,” stated the research team, led by infectious disease expert Elizabeth Hohmann from Massachusetts General Hospital and Bernd Schnabl, a gastroenterologist at the University of California San Diego.
The elevated ethanol levels in these patients often lead to liver damage, alongside various social and legal challenges.
The impetus for this study arose in 2019 when microbiologist Jing Yuan, based at Beijing’s Capital Institute of Pediatrics, received numerous calls from patients eager to undergo testing for ABS. Yuan, who published a study linking the bacterium Klebsiella pneumoniae to ABS—contradicting earlier beliefs that yeast might be the cause—guided these calls to Schnabl, who initiated recruitment for further research.
The comparison of gut microbiomes between ABS patients and their household members allowed the researchers to better account for environmental and dietary influences on gut health. The results showed that bacterial cultures from patients experiencing symptoms produced more ethanol than those in remission or from unaffected household partners, which correlated with measured blood alcohol levels.
Both Klebsiella pneumoniae and Escherichia coli, known ethanol producers, were found in higher amounts among ABS patients, with the latter particularly prevalent during symptom flare-ups.
In a notable case, one patient showed significant improvement after receiving two stool transplants from an unaffected donor, maintaining remission for over 16 months and reportedly returning to normal behavior.
The research suggests that ABS patients might benefit from dietary modifications or interventions like stool transplants or probiotics that support gut bacteria capable of efficiently metabolizing ethanol. However, Schnabl is careful to note that some ABS cases might still be linked to fungi or yeast.
There are also opportunities for future treatments to focus on bacterial genes associated with metabolic pathways that were more active during remission, potentially alleviating symptoms.
The researchers pointed out that ABS participants displayed extreme imbalances in their gut microbiomes. Other studies have indicated low ethanol production in individuals with diabetes, linking ethanol-producing gut microbes to fatty liver disease, which is the most prevalent liver condition worldwide.
This raises interesting questions about the frequency of gut microbial ethanol production in the general population, as well as its potential health implications. The researchers emphasized the significance of the gut microbiome and its metabolites in relation to overall health.
The findings have been published in Nature Microbiology.
