A new study shows that an ancient bacterium found in a thousand-year-old ice cave in Romania exhibits resistance to several commonly used modern antibiotics, indicating that bacterial resistance can form through natural evolution.
According to Xinhua News Agency, this bacterium was discovered in an ice layer of a Romanian cave that formed around 5,000 years ago. Researchers from institutions such as the Institute of Biology Bucharest of the Romanian Academy extracted a 25-meter-long ice core from the cave, isolated various bacterial strains from it, and conducted genomic sequencing analysis to study their cold tolerance mechanisms and genes related to drug resistance.
The researchers tested one of these psychrophilic bacterial strains, named SC65A.3, with 28 clinically used or reserve antibiotics from 10 classes, and found it was resistant to 10 of them. These included rifampicin, vancomycin, and ciprofloxacin—drugs used to treat common infections.
SC65A.3 is also the first known psychrophilic bacterial strain found to be resistant to antibiotics such as trimethoprim, clindamycin, and metronidazole.
The study also found that SC65A.3 carries over a hundred genes related to antibiotic resistance and can inhibit the growth of several multi-drug-resistant "superbugs". It also possesses unique enzymatic activities with potential biotechnological applications.
The researchers believe that strains capable of surviving in cold environments may serve as a “natural reservoir” for antibiotic resistance genes. The study of ancient microorganisms such as SC65A.3 demonstrates how antibiotic resistance can evolve in the natural environment—well before the use of modern antibiotics.
The researchers stated that with the global issue of antibiotic resistance growing increasingly severe, in-depth studies of such ancient microorganisms will help our understanding of the natural evolutionary process of antibiotic resistance mechanisms and may provide new ideas for developing novel drugs and biotechnological products.
They also warned that with the intensification of global climate change, if melting ice releases such ancient microorganisms, their resistance genes could be transferred to modern bacteria, thereby raising the global risk of antibiotic resistance.
This research was recently published in the international academic journal Frontiers in Microbiology.