Tasha Santiago-Rodriguez of California Polytechnic State University in San Louis Opisbo, spoke at the annual meeting of the American Society for Microbiology last month.
She and her team studied the DNA of bacteria taken from the guts of three Incan mummies from the 10th to the 14th centuries, and three Italian mummies who died between the 15th and 18th centuries. What they discovered shocked everyone.
Santiago-Rodriguez said, “At first we were very surprised,” reports New Scientist.
The research team discovered a whole array of genes in the bacteria that are resistant to most modern-day antibiotics, including penicillin, vancomycin, and tetracycline. Some of the genes were found in bacteria that are known to be resistant to antibiotics today.
This is what was really interesting – The team also found bacteria that we know are not resistant to antibiotics, yet these bacteria still contained the genes for resistance as well. Yes, it is confusing. How is it possible that 1.000-year-old bacteria developed genes that are resistant to antibiotics used today?
A previous study finds antibiotic-resistant genes
This latest discovery is not the first time gut bacteria in ancient mummies has been studied or for that matter gone through gene-sequencing. In 2015, an international team in Italy discovered genes linked to antibiotic resistance in an 11th-century mummy found in the Andes Mountains.
The research team found many genes in the gut bacteria that would have been antibiotic resistant using today’s antibiotics, particularly fosfomycin and vancomycin, they reported in PLOS One.
The researchers took particular note of the gene showing resistance to vancomycin, saying “Vancomycin was discovered more than 50 years ago, and vancomycin-resistant genes have been mainly implicated with the increased use of this antibiotic.”
Ancient bacteria and the natural world
So how is it that antibiotic resistance could have developed before humans discovered the first antibiotics? Santiago-Rodriguez and her colleagues remind us that human-made antibiotics are merely taking advantage of what is available to us in the natural world.
Alexander Fleming is credited with discovering our first antibiotic, penicillin in 1928. Fleming was working with a mold, Penicillium rubens, and found that if it was grown on the appropriate substrate, it would exude a substance with antibiotic properties, which he called penicillin.
Like penicillin, many other medications we use today to treat everything from headaches to infections, are derived from plants and other substances found in nature. This also applies to many of the remedies and cures used in folk-medicine and all those “home remedies” handed down for generations.
So it makes sense that as plants and other organisms evolved over millions of years, some developed in a selective way that gave them the advantage during competition with bacteria for food, making the organisms resistant to bacteria.
“It’s ridiculous to think the evolution of antibiotic resistance began when penicillin was discovered,” said team-member Raul Cano, also at California Polytechnic State University, at the meeting while discussing the findings. “It’s been going on for 2 billion years.”
