A study published Tuesday in the journal Frontiers in Microbiology describes Psychrobacter SC65A.3, a bacterial strain discovered frozen inside 5,000-year-old layers of cave ice in Romania. Testing revealed that SC65A.3 is resistant to 10 modern antibiotics and carries more than 100 genes linked to resistance despite never being exposed to these drugs.
While exposure to antibiotics amplifies the prevalence of resistance genes, it does not allow microbes to develop protective traits. Those depend on random genetic mutations and the constant pressure to out-perform other microorganisms in the environment.
The Psychrobacter SC65A.3 strain is a perfect example of how natural processes lead to antibiotic resistance. Purcarea and her colleagues found it inside an 82-foot ice core from theScarisoara Ice Cave in northwestern Romania. The core contains 13,000 years of climatic history, including the 5,000-year-old ice layers that contained SC65A.3.
