The bacteria, discovered by scientists deep inside a cave set into a Romanian mountain range, has 100 genes that would grant it resistance to humanity’s most vital medicine
Antibiotic-resistant bacteria recovered from deep inside an ice cave is resistant to up to 10 different types of the medicine – igniting superbug fears, but scientists believe they could potentially help scale a mountainous challenge.
A recent bacterial study has uncovered organisms preserved in a 5,000-year-old layer of ice inside the Scarisoara Ice Cave in the Romanian Apuseni Mountains which boasts sweeping resistance to modern antibiotics. The organisms have bred in extreme conditions, granting them up to 100 resistance-related genes, researchers found, despite having existed millenia before the invention of the vital medicine.
Scientists have explained, however, that despite the fears in recent years that resistance like this could take humanity back to the “dark ages”, the latest discovery could be medically vital.
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The research team from Romania explained that the bacteria have evolved to adapt to all of Earth’s most extreme conditions, from scorching heat to temperatures well below zero. Ice caves are just one of the environments hosting a range of microorganisms that represent a source of genetic diversity that has not yet been studied extensively.
They found it could be an opportunity for developing new ways to prevent the rise of antibiotic resistance and study how resistance naturally evolves and spreads.
Study lead Dr Cristina Purcarea, a senior scientist at the Institute of Biology, Bucharest, said the bacterial strain, named Psychrobacter SC65A.3, could inhibit the growth of potentially dangerous bugs. She said: “The Psychrobacter SC65A.3 bacterial strain isolated from Scarisoara Ice Cave, despite its ancient origin, shows resistance to multiple modern antibiotics and carries over 100 resistance-related genes.”
“But it can also inhibit the growth of several major antibiotic-resistant ‘superbugs’ and showed important enzymatic activities with important biotechnological potential.”
Dr Purcarea explained that Psychrobacter SC65A.3 is a strain of the genus Psychrobacter, which are bacteria adapted to cold environments. Some species can cause infections in both humans or animals. The bacteria have biotechnological potential, but the antibiotic resistance profiles of the bacteria were largely unknown.
The scientist added: “Studying microbes such as Psychrobacter SC65A.3 retrieved from millennia-old cave ice deposits reveals how antibiotic resistance evolved naturally in the environment, long before modern antibiotics were ever used.”
The research team drilled a 25-metre ice core from the area of the cave known as the Great Hall, representing a 13,000-year timeline. To avoid contamination, the ice fragments taken from the core were placed in sterile bags and kept frozen on their way back to the lab.
The research team isolated various bacterial strains and sequenced their genome in the lab to determine which genes allow the strain to survive in low temperatures and which confer antimicrobial resistance and activity.
They tested for resistance of the SC65A strain against 28 antibiotics from 10 classes that are routinely used to or reserved for treating bacterial infections. The drugs tested included antibiotics that have previously been identified to possess resistance genes or mutations that give them the ability to resist drug effects.
That way, they could test whether predicted mechanisms translated into measurable resistance. Dr Purcarea said: “The 10 antibiotics we found resistance to are widely used in oral and injectable therapies used to treat a range of serious bacterial infections in clinical practice.”
Diseases such as tuberculosis (TB), colitis, and urinary tract infections (UTIs) can be treated with some of the antibiotics that the researchers found resistance to, including rifampicin, vancomycin, and ciprofloxacin.
SC65A.3 is the first Psychrobacter strain for which resistance to certain antibiotics – including trimethoprim, clindamycin, and metronidazole – was found. Those antibiotics are used to treat UTIs, infections of lungs, skin, or blood, and the reproductive system.
SC65A.3’s resistance profile suggests that strains capable of surviving in cold environments could act as “reservoirs” of resistance genes which are specific DNA sequences that help them survive exposure to drugs, according to the research team. They say bacterial strains such as the one they examined hold both a threat and a promise.
Dr Purcarea said: “If melting ice releases these microbes, these genes could spread to modern bacteria, adding to the global challenge of antibiotic resistance.
“On the other hand, they produce unique enzymes and antimicrobial compounds that could inspire new antibiotics, industrial enzymes, and other biotechnological innovations.”
In the Psychrobacter SC65A.3 genome, the researchers found almost 600 genes with unknown functions, suggesting a yet untapped source for discovering new biological mechanisms. Analysis of the genome, published in the journal Frontiers in Microbiology, also revealed 11 genes that are potentially able to kill or stop the growth of other bacteria, fungi, and viruses.
