Gallstone from mummified 16th century prince may provide clues to fight E. coli

HAMILTON, Ontario — A gallstone taken from the mummified body of a 16th century Italian prince is providing vital clues in the battle against a notorious superbug.

Scientists have constructed the first ancient genome of E. coli – responsible for thousands of deaths around the world each year – using fragments from the preserved remains of Neapolitan nobleman Giovani d’Avalos.

The prince, who was 48 when he died in 1586, is thought to have suffered from chronic inflammation of the gallbladder due to gallstones, which have been linked to E. coli. The superbug is a major public health concern that causes approximately 265,000 illnesses across the United States each year.

Scientists refer to it as a commensal, a bacterium which lives inside people and can act as an opportunistic pathogen, infecting its host when they’re under stress, suffering from disease, or a weakened immune system.

16th century mummy
Researchers reconstruct the genome of E. coli, using fragments from gallstone of 16th century mummy. (Credit: McMaster University)

E. coli still a medical mystery

However, the research team explained that the pathogen’s full evolutionary history remains a mystery, including when it acquired antibiotic resistance.

Unlike historic pandemics like the Black Death, which lingered for centuries and killed around 200 million people globally, there are no historical records of deaths attributable to commensals — despite their impact on human health.

“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 commmensals driven by the stress of lives lived,” says research leader Professor Hendrik Poinar in a university release.

The evolutionary geneticist says modern E. coli is a common bacterium in the intestines of both healthy people and animals. While most forms are harmless, some strains can cause serious and potentially fatal cases of food poisoning and bloodstream infections. The bacterium is also especially resistant to treatment with antibiotics.

Researchers explain that having the genome from a 400-year-old ancestor to the modern superbug provides scientists with a “point of comparison” for studying how it’s evolved and adapted since over the years.

The mummified remains used in the new study come from a group of Italian nobles recovered from the Abbey of Saint Domenico Maggiore in Naples in 1983. The research team conducted a detailed analysis of one of the well-preserved individuals, d’Avalos, a Neapolitan noble from the Renaissance period.

“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,” says study lead author George Long, a graduate student of bioinformatics at McMaster.

George Long
George Long is co-lead author of the study and a graduate student of bioinformatics in the Department of Anthropology. (Credit: McMaster University)

Creating a blueprint for ‘opportunistic pathogens’

Long explains that this study was particularly remarkable because E. coli is both “complex and ubiquitous” — living not only in the ground but also in the human microbiome.

Researchers had to carefully isolate fragments of the bacterium, which had degraded by environmental contamination from several sources.

“It was so stirring to be able to type this ancient E. coli and find that while unique it fell within a phylogenetic lineage characteristic of human commensals that is today still causing gallstones,” says Professor Erick Denamur, the leader of the French section of the research team.

“We were able to identify what was an opportunistic pathogen, dig down to the functions of the genome, and to provide guidelines to aid researchers who may be exploring other, hidden pathogens,” Long adds.

The findings appear online in the journal Communications Biology.

South West News Service writer Stephen Beech contributed to this report.