Whether they come from Egypt, Chile, Italy or other countries, mummies are real treasure troves to learn more about the way of life of the ancient populations, but also about their state of health. Thanks to the treatment they underwent, many of them testified to the presence of various diseases or infections in the deceased.
Some even showed traces of parasites, fungi or even bacteria. A study published in the journal this week communication biology today offers a new example. An international team has succeeded in identifying and reconstructing the first ancient genome of a bacterium from a 16th-century Italian mummy Escherichia coli.
E. coli is a so-called commensal bacterium. It is found naturally in our gut (and that of all mammals) without causing any harm. The vast majority of strains are therefore considered harmless. However, some can cause food poisoning and serious infections, sometimes fatal.
It is particular E. coli which is regularly involved in product recalls and cases of poisoning, as was the case recently with the Buitoni brand. But what was before? According to scientists, there is currently no historical record of deaths caused by opportunistic pathogens like this bacterium.
The gallstones of a nobleman who died in 1586
Hence the importance of the advances made by the team of Canadian, Italian and French researchers. To conduct their study, they used the mummified remains of Italian nobles found in the Abbey of Saint Domenico Maggiore in Naples in 1983. Among them was Giovani d’Avalos, a Neapolitan noble who died in 1586 at the age of 48. .
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Analyzes performed on his remains revealed that the man had intact gallstones, which could be linked to chronic inflammation of the gallbladder. “When we examined these remains, there was no evidence that this man was a carrier of E. coli‘ said George Long, a researcher at McMaster University (Canada) and first author of the report.
“Unlike an infection like smallpox, there were no physiological signs. Nobody knew what he had‘ he continued in a university press release until scientists became interested in the man’s gallstones, which revealed the presence of the famous bacterium.
Fragments were extracted from one of the calculations and entrusted to the team of Professor Erick Denamur from the University of Paris Cité, specialist in population geneticsE. coli. Thanks to meticulous work, the scientists managed to isolate parts of the 500-year-old bacterium and to reconstruct and analyze its genome.
“It was so moving to type this ancient E. coli and discover that it was almost unique, but that it was part of a phylogenetic lineage characteristic of the human commensals that cause cholecystitis today (chronic inflammation of the gallbladder, note d. Red.), commented Erick Denamur in a press release.
A new point of comparison
According to the team, this is the first ancient genome ofE. coli restored. And it opens up many perspectives. By providing a point of comparison with modern strains, it provides new information for studying the evolution of the bacterium and its adaptation over the past five centuries.
For example, his analysis revealed the absence of certain key virulence factors observed in current highly pathogenic strains such as E. coli that produce Shiga toxins (STEC). E. coli enterohemorrhagic disease (ETEC), which can cause diarrhea and potentially fatal complications.
This genome also offers unprecedented insight into the diseases that populations once suffered from, less well known than well-documented pandemics like the Black Death. “Our reconstruction of this ancient E. coli helps paint a more complete picture of the burden of opportunistic infections in the past.‘ the authors emphasize in their report.
Nonetheless, this work could also have implications for the present by helping to predict the potential developments ofE. coli in terms of virulence and resistance and also that of other opportunistic pathogens.
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