A bacterial strain preserved for 5,000 years that is resistant to 10 modern antibiotics was discovered in a Romanian ice cave, Euro News reported on Tuesday, citing a recent study.

The newly identified strain, called Psychrobacter SC65A.3, which is able to withstand multiple contemporary drugs, was found in ancient ice in Scarisoara Cave, one of Romania’s largest ice caves in the Apuseni Mountains.

Bacteria are known to survive for millennia in extreme environments, including deep ice layers, permafrost, oceans, and glacial lakes. Over time, they adapt to persist under such harsh conditions.

The researchers found that this cold-adapted Psychrobacter strain resists 10 antibiotics across eight classes.

“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,” said Cristina Purcarea, author of the study and scientist at the Institute of Biology Bucharest of the Romanian Academy.

How antibiotic resistance evolved

The cave contains an underground ice block about 13,000 years old and measuring 100,000 cubic metres, considered the largest and oldest underground ice block.

Purcarea said that studying microbes like SC65A.3 from ancient ice helps scientists understand how antibiotic resistance evolved naturally long before modern medicines existed.

Published in Frontiers in Microbiology, the study highlights the importance of researching cold-adapted microbes, especially as frozen habitats cover 20% of Earth’s surface and the climate crisis advances.

Antimicrobial resistance already causes millions of deaths globally each year, including more than 35,000 annually in Europe, a figure likely to increase.