A 5,000-year-old bacterium resistant to modern antibiotics has been discovered in a Romanian ice cave.
In the depths of Skerishoara Cave, one of Romania's largest ice caves, researchers have discovered a strain of Psychrobacter SC65A.3 bacteria preserved under a layer of ice that is approximately 5,000 years old. The ice block in the cave has a volume of approximately 100,000 cubic metres and is considered the largest and oldest underground ice mass, estimated to be around 13,000 years old.
The research team drilled a 25-metre core in the Great Hall area of the cave. While analysing the ice fragments, the researchers isolated several bacterial strains and sequenced their genomes to determine which genes are responsible for survival in low temperatures and antimicrobial resistance.
According to the author of the study, Cristina Purcariu from the Institute of Biology in Bucharest, Romanian Academy, the Psychrobacter SC65A.3 strain, despite its ancient origin, shows resistance to 10 modern antibiotics from 8 different classes and contains more than 100 genes associated with resistance. These are drugs widely used in clinical practice to treat serious bacterial infections, including tuberculosis, colitis and urinary tract infections.
Researchers emphasise that bacteria can survive for millennia in extreme conditions, under ice sheets, in permafrost, underwater or in glacial lakes. Studying such microorganisms makes it possible to trace how antibiotic resistance developed naturally long before their widespread use in medicine.
The results of the study are published in the journal Frontiers in Microbiology. The authors note that about 20 percent of the Earth's surface is frozen, and low temperatures are characteristic of a significant part of the biosphere. In the context of rapid climate change, understanding the properties of cold-adapted microorganisms is of particular importance.
Antimicrobial resistance remains one of the key global threats. It is estimated to cause millions of deaths worldwide each year. In Europe, this figure exceeds 35,000 cases per year and is projected to rise. According to the World Health Organisation, one in six bacterial infections worldwide is already resistant to standard treatment.
