Bacteria frozen for more than 5,000 years in an ancient underground ice cave have been found to be resistant to 10 modern antibiotics used to treat various diseases, surprising researchers.
On the 18th (local time), a research team led by Dr. Cristina Purcarea at the Institute of Biology Bucharest of the Romanian Academy reported in the scientific journal Frontiers in Microbiology that bacteria (Psychrobacter SC65A.3) discovered in Scarisoara Ice Cave showed resistance to 10 antibiotics in genome sequencing analysis and antibiotic experiments.
The research team said the bacterial strain buried in 5,000-year-old ice layers possessed more than 100 genes associated with antibiotic resistance. They added that this research could serve as a foundation for developing new strategies to prevent increasing antibiotic resistance and for understanding how resistance evolves and spreads in nature.
The team drilled a 25-meter ice core spanning 13,000 years from the "Great Hall" section of Scarisoara Ice Cave, Romania's largest glacier cave, and transported it to the laboratory in sterile frozen conditions for analysis.
The results revealed that bacteria (Psychrobacter SC65A.3) isolated from the 5,000-year-old ice layer showed resistance to multiple antibiotics and possessed more than 100 resistance-related genes. Testing resistance against 28 antibiotics across 10 classes—either routinely used for treating bacterial infections or reserved as backup drugs—confirmed resistance to 10 antibiotics widely used for treating various severe bacterial infections.
Psychrobacter SC65A.3 showed resistance to antibiotics including rifampicin, vancomycin, ciprofloxacin, trimethoprim, clindamycin, and metronidazole, which are used to treat infectious diseases such as tuberculosis, colitis, and urinary tract infections. Additionally, approximately 600 genes with unknown functions were discovered in the Psychrobacter SC65A.3 genome, along with 11 genes identified as having potential to kill or inhibit the growth of other bacteria, fungi, or viruses.
Dr. Purcarea said the antibiotic resistance of Psychrobacter bacteria had not been previously known. She added that studying this bacterium could reveal how antibiotic resistance evolved naturally long before modern antibiotics came into use.