Ancient bacteria from 5,000-year-old ice reveal antibiotic resistance

Romanian researchers recovered bacteria from a 5,000-year-old Scărișoara Cave ice core that showed resistance to several modern antibiotics; chemicals from the samples also inhibited multiple disease-causing bacteria.

Romanian scientists drilled a 25-metre ice core from the Scărișoara Cave and recovered bacteria that had been sealed for about 5,000 years. Laboratory analyses found these microbes could grow in cold and high-salt conditions and showed resistance to multiple modern antibiotics. Chemical extracts from the samples were able to kill or inhibit several types of bacteria that cause human disease. The researchers reported no evidence that the cave microbes are directly harmful to people. Key findings: - Bacteria were recovered from a 25-metre core of Scărișoara Cave ice dated to about 5,000 years ago. - Isolates grew in extreme cold and high-salinity laboratory conditions. - The samples showed resistance to ten modern antibiotics, including ciprofloxacin. - Chemical compounds produced by the cave bacteria inhibited 14 types of disease-causing bacteria, including several noted by the World Health Organization as high-priority pathogens. - There was no reported evidence that the recovered microbes are harmful to humans. - Scientists noted that resistance genes can move between environmental and disease-causing bacteria and that melting land ice could release long-dormant microbes and genetic material. Summary: The discovery highlights that antibiotic resistance genes have long existed in natural environments while those same environments can contain molecules that inhibit pathogens. Whether and how these chemical leads or genetic findings will be developed into new treatments or applications is undetermined at this time.