Researchers from the Romanian Academy have identified a 5,000-year-old bacterial strain preserved in ice that shows resistance to 10 widely used modern antibiotics.

The strain, isolated from Romania’s Scarisoara Ice Cave, was recovered from a 25-metre ice core extracted from an area known as the Great Hall. The core represents roughly 13,000 years of accumulated ice. To minimise contamination, samples were transported in sterile conditions and kept frozen before laboratory analysis.

According to a recent report by Daily Mail, the bacterium, named Psychrobacter SC65A.3, belongs to a genus previously associated with infections in humans and animals. In laboratory testing, researchers exposed the strain to 28 antibiotics spanning 10 classes commonly used in clinical practice, including treatments for tuberculosis, urinary tract infections (UTIs) and other serious bacterial diseases. The organism was found to be resistant to all 10 classes tested, including trimethoprim, clindamycin and metronidazole.

Genome sequencing revealed that the strain carries more than 100 genes linked to antibiotic resistance, along with 11 genes believed to kill or stop the growth of other bacteria, fungi, and viruses. Researchers also identified almost 600 genes with unknown functions, which they said could represent unexplored biological mechanisms.

The study comes amid broader scientific debate about the risks posed by thawing permafrost and glaciers as global temperatures rise. Separate research published in Proceedings of the Royal Society B has suggested that increased glacier melt in the Arctic may heighten the risk of viral “spillover”, in which pathogens move between species as changing environmental conditions bring them into new contact with hosts.