It was in January 2011, about a week after finishing a round of antibiotics for a thumb injury, that the man first started presenting a batch of unlikely symptoms: memory loss; brain fog; depression; aggression. His doctors couldn’t figure it out—and so, in 2014, they referred him to a psychiatrist who prescribed him a round of antidepressants. The man was later pulled over by police for allegedly driving under the influence. Despite having had nothing to drink, a breathalyser test indicated that he had the blood alcohol equivalent of someone who’d consumed 11 to 14 beverages, and he was arrested.
This story is the subject of a new report published in the BMJ Journal of Gastroenterology, titled: “Case report and literature review of auto-brewery syndrome: probably an underdiagnosed medical condition”. The report states that, following his arrest and at his aunt’s insistence, the 46-year-old man underwent a series of tests that eventually discovered traces of the fungus Saccharomyces cerevisiae (that is, brewer’s yeast) in his stool sample.
Saccharomyces cerevisiae is typically used during the brewing process to turn carbs into alcohol—and it was thus suspected that the man in question may have been experiencing a condition known as “auto-brewery symptom."
“Auto-brewery syndrome (ABS), also known as gut fermentation syndrome, is a rarely diagnosed medical condition in which the ingestion of carbohydrates results in endogenous alcohol production,” reads the report abstract. “The patient in this case report had fungal yeast forms in the upper small bowel and cecum, which likely fermented carbohydrates to alcohol.”
To test this, the man was given a carb-heavy meal while having his blood alcohol levels monitored. After eight hours, it elevated to 57 milligrams per decilitre—or the equivalent of about three to five standard drinks for someone his size. He was treated for ABS and prescribed anti-fungal medication. But after several weeks, his symptoms returned, and he started to get drunk again from the brewer’s yeast in his gut.
“The most significant event caused by one of his inebriations was a fall that caused intracranial [brain] bleeding and necessitated a transfer to a regional neurosurgical centre, where he had a complete spontaneous recovery in 10 days,” according to the report. After taking a different anti-fungal medication and cutting out carbs for six weeks, he finally recovered.
It’s since been hypothesised that the man’s exposure to antibiotics triggered his boozy symptoms, by changing his gastrointestinal microbiome and allowing for “fungal overgrowth." But this isn’t the only reported case of ABS in recent memory. In 2016, a New York woman blew a blood alcohol level that was more than four times the legal limit, but later had her charges dismissed after the judge received evidence that she suffered from the condition.
"I had never heard of auto-brewery syndrome before this case," attorney Joseph Marusak told CNN at the time. "But I knew something was amiss when the hospital police… wanted to release her immediately because she wasn't exhibiting any symptoms."
"That prompts me to get on the Internet and see if there is any sort of explanation for a weird reading," adds Marusak. "Up pops auto-brewery syndrome and away we go."
Authors of the BMJ report believe that ABS is “probably an underdiagnosed condition.”