Postmortem in vitro ethanol production-It could be more common than we think!

- Postmortem blood alcohol concentration (BAC) interpretation is a complex process.
- Postmortem in vivo/in vitro ethanol production could be more common than we think.
- The most common causes are microbial contamination and glucose fermentation.
- Assessment of postmortem BAC always deserves a thorough and careful interpretation.

The blood alcohol concentration (BAC) is the most frequent determination in a Forensic Toxicology Laboratory. Despite its apparent simplicity, the results interpretation can be complex and always have relevant social and legal implications, particularly in postmortem analysis. In the present report we describe the case of a 55-year-old male with an apparent natural death by myocardial infarction, whose initial BAC was 0.18 g/L but, in repeated determinations prompted by discrepancies observed in the first two, it rapidly increased to 0.85 g/L three days later, leading to the suspicion of in vitro ethanol production. A microbiological examination of the sample revealed the presence of the bacteria Escherichia coli and Enterococcus faecalis, and yeast Candida parapsilosis, known for their involvement in ethanol production. Although this is a case report and it is not meant to be generalizable, we discuss an existing large body of scientific literature showing the difficulties, limitations and some relevant medico-legal questions regarding BAC determinations in postmortem samples and their interpretation, particularly in the context of plausible in vitro ethanol production. The key conclusion is that evaluating a postmortem BAC is a complex and multifactorial process that always deserves a thorough analysis and a careful interpretation.