A preliminary investigation into the use of biosensors to screen stomach contents for selected poisons and drugs.

The bioluminescence response of two genetically modified (lux-marked) bacteria to potentially toxic compounds (PTCs) in stomach contents was monitored using an in vitro assay. Cells of Escherichia coli HB101 and Salmonella typhimurium both carrying the lux light producing gene on a plasmid (pUDC607) were added to stomach contents containing various concentrations of organic and inorganic compounds. There was some variability in the response of the two biosensors, but both were sensitive to the herbicides glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T); pentachlorophenol (PCP), and inorganic poisons arsenic and mercury at a concentration range likely to be found in stomach contents samples submitted for toxicological analysis. This study demonstrates that biosensor bioassays could be a useful preliminary screening tool in forensic toxicology and that such a toxicological screening should include more than one test organism to maximise the number of PTC's detected. The probability of false positive results from samples containing compounds that may interfere with the assay such as over-the-counter (OTC) drugs and caffeine in tea and coffee was also investigated. Of the substances tested only coffee has the potential to cause false positive results.