The Death Microbiome Could Inform Forensic Science And Medicine
The cells in your body are outnumbered 10 to one by microbial cells, and like it or not, eventually the microbes will win, reports The NewScientist.
Researchers have conducted the first study of the thanatomicrobiome or death microbiome, the gut microbes that take over your internal organs once you are dead.
The results could have applications in forensic science and medicine.
While we are alive, the 100 trillion bacteria resident in our gut work to aid digestion and keep the immune system functioning properly. These friendly bacteria also keep bad bacteria at bay by outcompeting them in exchange for a constant supply of food, reports The NewScientist.
After we die, cells leak carbohydrates, amino acids and lipids, causing a microbial feeding frenzy. The bacteria eventually escape the gut and swarm through the circulatory and lymph systems, spreading to organs that are shielded during life by the immune system, the NewScientist further elaborates.
For pathologists working out the time of death, research has focused on the way that insects and microbes from a corpse' environment take up residence in the flesh.
To study how a dead body decays in isolation, Peter Noble of Alabama State University in Montgomery sampled microbes from a selection of internal organs, as "these aren't influenced by environmental conditions," he says. He hoped to discover how long it took gut bacteria to reach each organs after death, and establish which species go where.
The team isolated and amplified bacterial genetic material from cadaver tissues to reveal the microbes present. Their samples came from the liver, spleen, brain and heart of 11 cadavers, between 20 and 240 hours after death.
In the newest cadavers, the researchers found bacteria such as Streptococcus, Lactobacillus and Escherichia coli, which mop up any oxygen left in the tissues after respiration stops.
As the time since death increased, the bacteria present were more likely to be those that can function without oxygen, such as Clostridium strains. Some of the cadavers harbored C. botulinum, which can cause botulism, and C. difficile, one of the main culprits in hospital infections.
So does this individual variation mean that we can use the microbiome of a dead body to identify unknown victims of crime or a disaster, by matching it to bacteria on the unwashed clothes of missing persons?
"The only way to answer this is with a really big sample of cadavers," says Sibyl Bucheli of the Sam Houston State University.
However, "The predictable shift in microbial colonization of a body means we can use microbes as a clock to estimate how long a body has been decomposing," says Bucheli.
Even if it turns out to be impractical as a method of identification, there are other potential uses. Sequencing the DNA present could confirm a suspected bacterial infection, identify an infection when the cause of death was unknown, or even help assess the efficacy of antibiotics in treating an infection, says John Cassella, a professor of forensic science at Staffordshire University, UK.
The research was published in Journal of Microbiological Methods.