The possible influence of micro-organisms and putrefaction in the production of GHB in post-mortem biological fluid

In recent years, the post-mortem production of the drug of abuse gamma-hydroxybutyric acid (GHB) in biological fluids (e.g. blood and urine) has caused various interpretative problems for toxicologists. Previously, other researchers have shown certain microbial species (Pseudomonas spp. and Clostridium aminobutyricum) possess the necessary enzymes to convert GABA to GHB. A preliminary investigation involving putrefied post-mortem blood indicated there was no observed relationship between "endogenous" GHB concentrations and concentrations of common putrefactive markers (tryptamine and phenyl-2-ethylamine). Microbiological analysis identified the presence of various micro-organisms: Clostridia spp., Escherichia coli, Proteus vulgaris, Enterococcus faecalis and Aeromonoas spp. Equine plasma, human blood and urine samples were inoculated with these and an additional micro-organism (Pseudomonas aeruginosa) and incubated at 22 degrees C for 1 month. Following comparison with control samples and pre-inoculation concentrations, the data indicated an apparent production of GHB in unpreserved P. aeruginosa inoculated blood (2.3 mg/l). All other fluoride-preserved and unpreserved samples (including controls) had GHB concentrations <1mg/l. Although this concentration is lower than is typically associated with "endogenous" post-mortem GHB concentrations, this paper proposes a potential microbial production of GHB with time.