Doctors have reported the case of a man who started to ferment alcohol in his own gut after taking a common antibiotic.

The patient was an otherwise healthy man until 2011 when doctors prescribed him oral cephalexin, a common antibiotic after a thumb injury.

Curious Symptoms And Personality Changes

A week after starting the course of his treatment, the man started to experience curious symptoms such as memory loss, brain fog, and episodes of depression. He also started to go through some personality changes. In 2014, he was referred to a psychiatrist who prescribed him with antidepressants.

Things took an interesting turn when one morning, the man was pulled over by police on suspicion of driving under the influence of alcohol. The incident eventually unveiled his strange condition.

He refused to take a breathalyser test, but he was hospitalized. Tests showed that his blood alcohol level was 200 mg/dL, which is equivalent to having about seven to 10 drinks, and enough to cause a range of dangerous symptoms such as nausea, vomiting, memory blackout, and loss of consciousness.

The man insisted that he did not drink at all, so after the incident, his aunt, who has heard of similar cases of people getting drunk without drinking any alcohol, started to monitor his alcohol level. She also encouraged him to go to a physician who was known for treating someone with the same condition.

After a carbohydrate test, where the man was given a carbohydrate meal and his blood-alcohol levels monitored over a few hours, doctors found Saccharomyces cerevisiae (brewer's yeast) in his stool despite that he did not consume any alcohol.

Auto-brewery Syndrome

The man was diagnosed with the rare condition known as auto-brewery syndrome (ABS), or gut fermentation syndrome, which causes people's guts to produce small amounts of alcohol when digesting sugary and starchy food.

Doctors said his is the first documented case of ABS that resulted from antibiotics. He was treated with a combination of antifungal therapies and probiotics to treat his gut microflora.

"We postulate that the antibiotic altered his gut microbiome, allowing fungal growth," Fahad Malik, from Richmond University Medical Center, and colleagues wrote in the case report published in the BMJ Open Gastroenterology on Aug. 5.

"This diagnosis should be considered in any patient with positive manifestations of alcohol toxicity who denies alcohol ingestion."