The Science Behind Ethanol-Producing Microbes
The human body is a teeming ecosystem of microorganisms—bacteria, yeasts, and more—that play roles in everything from digestion to disease. According to Mbaye's comprehensive review, which analyzed over 5,000 articles, there are 61 bacterial species and 24 yeast species capable of producing ethanol (alcohol) as a byproduct of their metabolism. These include well-known culprits like Candida albicans (a common yeast linked to infections), Klebsiella pneumoniae, Clostridium species, Lactobacillus strains, and Saccharomyces cerevisiae (the yeast used in brewing). These microbes are part of our normal flora, residing in the gut, mouth, skin, and other areas.
In a DUI context, blood samples are drawn to measure blood alcohol concentration (BAC). To prevent natural decay or fermentation from altering the sample, labs add sodium fluoride as a preservative. The idea is that fluoride inhibits microbial activity, stopping any rogue bacteria or yeasts from fermenting sugars in the blood into ethanol. But here's where things get tricky: not all microbes are deterred by fluoride.
The Logic of Contamination: Why Blood Tests Aren't Bulletproof
Let's walk through the key questions that expose the weaknesses in relying solely on preserved blood samples for DUI prosecutions:
- Are there ethanol-producing microbes (yeasts and bacteria) in the environment that may contaminate a blood sample?
Yes. The Mbaye catalog focuses on human-associated microbes, but these same organisms are ubiquitous in our surroundings—on skin, in hospitals, or even in the air. Humans are, as the saying goes, pretty dirty creatures when it comes to microbes! A simple skin puncture during blood draw can introduce them directly into the sample.
- Do blood collection procedures eliminate ALL ethanol-producing microbes from contaminating the blood sample?
No, it's not possible. Standard protocols involve sterilizing the site with betadine wipes and using vacuum-sealed tubes, but absolute sterility is a myth. Contamination can occur from improper handling, needle insertion, or even post-collection storage issues.
Fermentation is ALWAYS an issue in blood samples because the disinfection process is fundamentally flawed in real-world practice. It takes at least three minutes of contact time on top of the skin for the disinfectant to inactivate any microbes present. In fact in surgical settings, a 3-minute minimum contact time is standard for Betadine (povidone-iodine) to effectively disinfect skin and kill most pathogens during surgical scrubbing or preparation, involving steps like scrubbing hands for 3-5 minutes, rinsing with soap and water, and repeating the betadine vigorous scrub for another 3-5 minutes (not just a simple wipe-down), to minimize infection risks in clinical settings while following product-specific instructions. However, over the past 30 years of reviewing cases, I have never seen a disinfectant remain on the skin for more than one minute—usually, it's less than that. Even IF the skin surface was properly disinfected, there are microbes that live below the skin surface, and the disinfectant never gets to them. Additionally, the blood tube tops are not sterile and are never disinfected; they are ALWAYS a source of microbe contamination.
- Are there fluoride-resistant ethanol-producing microbes in the environment that may contaminate a blood sample?
Yes. Research shows that certain microbes, like Candida albicans—prominently featured in the Mbaye catalog—can produce ethanol even in the presence of sodium fluoride. Studies on blood fermentation in DUI cases confirm that this yeast, a common human pathogen, thrives and ferments despite the preservative, leading to artificially elevated BAC readings.
- Have all the ethanol-producing microbes in the environment that may contaminate a blood sample been cataloged as to their fluoride resistance?
No. The Mbaye study is a groundbreaking repertoire, but it doesn't test for fluoride resistance across all 85 microbes. Broader scientific literature reveals gaps; while some like Candida are known to be resistant, others (e.g., certain Clostridium or Lactobacillus strains) may vary, and new variants emerge. We simply don't have a complete list.
- Is it possible for any 'chemist' state witness to rule out the presence of a fluoride-resistant ethanol-producing microbe in the blood sample tested?
No, and certainly not without specific microbiologic testing. A forensic chemist might testify that the sample was preserved properly, but they can't detect or exclude microbial activity without culturing the sample or using advanced DNA sequencing—tests rarely performed in standard DUI labs. This leaves room for reasonable doubt.
These points aren't hypothetical; they've been raised in court cases across the country, including instances where fermentation led to BAC readings above the legal limit in alcohol-free samples. In Georgia, where DUI laws are stringent and blood tests are increasingly common, this contamination risk can mean the difference between a conviction and an acquittal.
Why This Matters for Georgia DUI Defendants
In Georgia, a BAC of 0.08% or higher can trigger severe penalties: license suspension, fines, jail time, and a permanent record. But if your blood sample was contaminated by one of these human-associated microbes, the results could be inflated or entirely fabricated. The Mbaye catalog highlights that these ethanol producers aren't rare—they're part of us. Skin flora during the draw, improper tube sealing, or delayed refrigeration can all invite fermentation. Prosecutors often dismiss this as a "defense tactic," but the science backs it up: without ruling out microbes, the test's reliability is questionable.
This is especially relevant in Gwinnett County, where traffic stops and DUI arrests are frequent. I've successfully challenged blood evidence by highlighting these flaws, cross-examining state experts on their inability to exclude contamination, and presenting scientific literature like the Mbaye study.
Protecting Your Rights: What to Do Next
If you've been arrested for DUI based on a blood test, don't assume the results are infallible. Microbial contamination is a real, science-backed defense that can create reasonable doubt. As your Gwinnett DUI attorney, I'll scrutinize every step—from collection to analysis—to uncover weaknesses like these.
Contact my office today for a free consultation. With my track record of wins in DUI cases, we'll build a strong defense tailored to your situation. Remember, knowledge is power—especially when microbes might be brewing trouble in your case.
George Creal is a DUI defense attorney practicing in Gwinnett County, Georgia. This blog post is for informational purposes only and does not constitute legal advice.
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