Photo Credit: Division of Paleopathology of the University of PISA
E.coli is a type of bacteria that has been a major health concern and has led to numerous deaths. While the bacterium is found in the intestines of healthy humans and animals, the history of its evolution has remained unknown. Now, researchers, at McMaster University, have successfully reconstructed the first ancient genome of E.coli by using the gallstone of a 16th-century Italian mummy. E.coli doesn't lead to pandemics and is rather referred to as a commensal. Such types of bacteria hole up inside our bodies and wait to attack the host when it becomes vulnerable. They usually attack in conditions like stress, immunodeficiency, or illness.
Pandemic like the Black Death, which claimed roughly 200 million deaths across the globe, is well documented. But, there is no historical data available on the lives lost to E.coli, even when the bacterium has also impacted human health significantly.
“A strict focus on pandemic-causing pathogens as the sole narrative of mass mortality in our past misses the large burden that stems from opportunistic commensals driven by the stress of lives lived,” said evolutionary geneticist Hendrik Poinar, director of McMaster's Ancient DNA Centre and a principal investigator at the university's Michael G. DeGroote Institute for Infectious Disease Research.
In the study, published in Communication Biology, researchers aimed at creating the 400-year-old ancestor of E.coli that would give them an insight into its evolution so far. They used fragments from mummified bodies of a group of Italian nobles that were unearthed form the Abbey of Saint Domenico Maggiore in Naples in 1983.
The team analysed the mummy of one of the nobles who is believed to have died in 1586 at the age of 48. Researchers also noted that the individual had gallstones and suffered chronic inflammation of the gallbladder due to this.
“When we were examining these remains, there was no evidence to say this man had E. coli. Unlike an infection like smallpox, there are no physiological indicators. No one knew what it was,” said George Long, a graduate student of bioinformatics at McMaster. Long is also the lead author of the study and conducted the analysis of the mummy.
Researchers have isolated the fragments of the bacterium from the body and used the material to develop the genome. With this, they were able to understand the functions of the genome and now hope to aid other researchers who are in search for such hidden pathogens.
Most forms of E.coli do not pose a danger to their host while they live in their intestines. But, some strains have been found to cause even fatal food poisoning outbreaks and bloodstream infections. In addition, E.coli is adaptable which makes it resistant to treatments.