Auto-Brewery Syndrome (ABS)

**Auto-Brewery Syndrome (ABS)**, also referred to as **gut fermentation syndrome**, is a rare and likely underdiagnosed medical condition in which gut microbes (bacteria and/or yeast) ferment carbohydrates into ethanol (alcohol) within the gastrointestinal tract. This leads to elevated blood alcohol levels, causing symptoms of intoxication even when the individual has not consumed any alcoholic beverages.

### **Key Features of Auto-Brewery Syndrome (ABS):**

#### **Symptoms:**

• **Intoxication-like effects** without alcohol consumption:
• Slurred speech
• Dizziness
• Poor coordination
• Cognitive impairment
• **Brain fog** and difficulty concentrating
• Fatigue
• Social, legal, or professional issues similar to those faced by individuals with alcohol use disorder (e.g., DUI charges or workplace concerns)
• Potential mood changes, irritability, or confusion

#### **Underlying Cause:**

The condition is caused by an overgrowth of ethanol-producing microbes in the gut. These microbes ferment dietary carbohydrates (like sugar or starch) into alcohol. The most commonly implicated organisms include:

• **Klebsiella pneumoniae**
• **Escherichia coli (E. coli)**
• Occasionally, certain **yeast species** (e.g., *Saccharomyces cerevisiae*, also known as brewer's yeast)

#### **Diagnosis:**

Diagnosis of ABS is challenging and often delayed due to its rarity and the nonspecific nature of its symptoms. The following diagnostic tools are used:

1. **Oral Glucose Challenge Test**:

• The patient consumes a glucose-rich solution, and blood alcohol levels are monitored over time.
• A rise in blood alcohol levels above the legal driving limit (without alcohol consumption) confirms gut-driven ethanol production.

2. **Stool Analysis**:

• Stool samples are analyzed to identify ethanol-producing microbes, such as *Klebsiella pneumoniae* or *E. coli*.
• Studies of fermentation pathways may reveal heightened microbial activity leading to excess ethanol production.

3. **Blood Alcohol Testing**:

• Elevated blood alcohol levels in the absence of alcohol ingestion provide critical evidence.

#### **Treatment Options:**

Treatment for ABS focuses on reducing the overgrowth of ethanol-producing microbes and restoring gut microbial balance. Approaches include:

1. **Selective Antibiotics**:

• Used to target and reduce overgrowth of specific ethanol-producing bacteria like *Klebsiella pneumoniae* or *E. coli*.

2. **Probiotics and Prebiotics**:

• Probiotics (beneficial bacteria) and prebiotics (compounds that promote the growth of healthy gut microbes) may help restore a balanced gut microbiome.

3. **Antifungal Medications**:

• If yeast (e.g., *Saccharomyces cerevisiae*) is involved, antifungal drugs may be prescribed.

4. **Dietary Modifications**:

• Reducing carbohydrate and sugar intake can limit the substrate available for fermentation by gut microbes.

5. **Fecal Microbiota Transplant (FMT)**:

• A promising treatment in which healthy donor stool is transplanted to the patient to restore a balanced gut microbiome.
• One patient in a recent study achieved long-term remission after repeated FMT treatments.

#### **Recent Research and Findings:**

• In a 2019 case, *Klebsiella pneumoniae* was identified as a major cause of ABS in one patient.
• Dr. Bernd Schnabl from UC San Diego created the largest cohort of ABS patients to date, studying 22 individuals with confirmed cases.
• Stool studies revealed that *E. coli* and *Klebsiella pneumoniae* were the primary ethanol-producing microbes, with heightened fermentation pathways during symptom flares.

#### **Prevalence and Underdiagnosis:**

Although ABS is still considered rare, it may be more common than currently recognized. Many patients may have mild symptoms, such as fatigue or brain fog, which are often attributed to other conditions. Physicians are encouraged to consider ABS in cases of unexplained intoxication or cognitive symptoms, especially when blood alcohol levels are inexplicably elevated.

### **Key Takeaways:**

• Auto-Brewery Syndrome is a condition where gut microbes produce alcohol, leading to symptoms of intoxication without alcohol consumption.
• Diagnosis involves glucose challenge tests, blood alcohol testing, and stool analysis for ethanol-producing microbes.
• Treatments include antibiotics, probiotics, dietary changes, antifungals, and fecal microbiota transplants.
• While rare, ABS may be underdiagnosed, and awareness among healthcare providers is crucial for timely identification and management.