Bioluminescent bacteria have potential as a marker of drowning in seawater: Two immersed cadavers retrieved near estuaries

We detected numerous bioluminescent bacteria in blood samples from two cadavers that had been immersed in estuarine environments. Autopsy, diatomaceous and toxicological findings indicated death by drowning, which agreed with environmental aspects and the findings of police investigations. Bioluminescent bacteria appeared in blood samples cultured on selective agar containing 2%, 3% and 4% NaCl after about 18 h. Blood from the left side of the heart, the right side of the heart and the femoral vein generated 7.0 × 102, 2.0 × 104 and 8.0 × 102 cfu/ml of blood (case 1), and 1.8 × 104, 1.1 × 103 and 2.5 × 101 cfu/ml (case 2) of bioluminescent colonies, respectively, in agar containing 4% NaCl. Homologous analysis based on the 16S rRNA gene also identified the bioluminescent colonies as Vibrio fischeri and V. harveyi, which normally inhabit seawater. This simple assay might serve as an additional indicator to support a conclusion of death by drowning together with the diatom test.