A bacterial strain, isolated from an underground ice cave and untouched by modern antibiotics for at least 5,000 years, has demonstrated resistance to those same drugs, scientists have discovered. The finding, while potentially concerning, also offers a unique opportunity to identify novel antimicrobial compounds.
Carmen Chifiriuc, a professor of microbiology at the University of Bucharest, described the discovery as “a very interesting finding, opening the way to many other questions and research directions for the future,” in a statement.
Published Tuesday in the scientific journal Frontiers in Microbiology, the research details the first genomic analysis of the specific bacterial strain discovered by Chifiriuc and her team, as well as the first characterization of ancient resistomes in this largely unexplored environment. The study underscores the complex and ancient origins of antibiotic resistance, a growing global health crisis.
Samples were collected from ice layers thousands of years classic within the Scarisoara ice cave in Romania. It was there researchers identified the Psychrobacter SC65A.3 strain, which exhibited resistance to 10 classes of antibiotics commonly used to treat conditions like tuberculosis, colitis, and urinary tract infections.
The Natural History of Antibiotic Resistance
For decades, medical scientists studying bacterial resistance to antibiotics have focused on how modern medicine has driven certain bacteria to adapt and mutate in order to survive, Chifiriuc explained. However, this research suggests a more fundamental process at play.
“But it’s not like that,” she said. “Antimicrobial resistance is a natural phenomenon. It developed as part of these bacteria’s ability to adapt and acquire competitive advantages in their natural ecosystems.”
The ability of bacteria to resist compounds and chemicals that could kill them is as old as the bacteria themselves, Chifiriuc noted. But the intensive use of modern antibiotics over the last several decades has accelerated the process, making bacteria increasingly capable of surviving in hostile environments.
“What actually happened is that after the discovery of antibiotics, we used them intensively, and under the selective pressure of the huge amounts of antibiotics released into the environment, these bacteria exploited their natural mechanisms,” she stated. “They perfected them to be more and more competitive and to ensure this survival capacity in the presence of high concentrations of antibiotics.”
In their glacial environment, the bacteria examined by the researchers had developed genes resistant to antibiotics used to treat a range of illnesses.
Researchers caution that the newly discovered microbes could potentially transfer their antibiotic resistance genes to other, more harmful bacteria, exacerbating an already urgent global problem.
A Potential Source of New Antibiotics
However, the discovery also presents an opportunity to help solve the problem, according to the researchers. If bacteria can evolve resistance to certain antibiotics, they can also produce their own antimicrobial compounds to defend against competing bacteria.
Chifiriuc said the research team has already tested the antimicrobial properties of Psychrobacter SC65A.3 on other bacteria known to be highly antibiotic-resistant, “with very good results.”
“We will perform this biochemical analysis of the nature of these compounds, and we hope… to locate a really new compound, different from other classes of antibiotics, which could buy us some time in our fight against antimicrobial resistance,” she said.
Discovering a new antimicrobial substance to which harmful bacteria are not resistant would allow doctors to more effectively treat patients with certain dangerous infections, Chifiriuc added.
Even as new discoveries are made, Chifiriuc emphasized the need for continued vigilance in the fight against harmful bacteria, noting that they have survived for more than 3.5 billion years for a reason.
“One of the greatest Romanian microbiologists used to say that bacteria will have the last word. Half of the biomass of this planet is made up of microorganisms, which are very generous and therefore adapt very easily, but they don’t preserve it to themselves,” she said.
“They don’t protect their discoveries with patents or publications; they generously share these mechanisms with other bacteria to help them stay one step ahead of us.”
