Scientists isolated the Psychrobacter SC65A.3 bacterium from a 5000-year-old layer of ice in Romania's Scărișoara Ice Cave[1][2][3]. The sample came from a 25-meter-long ice core excavated from a section called the Great Hall[1][2][3]. This cold-loving microbe survived in an extremely cold environment with limited nutrients[1][3]. Despite its ancient origin, it is resistant to several modern antibiotics, specifically to 10 of the 28 tested drugs[2]. The bacterium carries more than 100 resistance-related genes[1][2]. A study published in the journal Frontiers in Microbiology confirms that resistance is a natural evolutionary process taking place over millions of years[1][2]. The research was led by a team from the Institute of Biology Bucharest led by microbiologist Cristina Purcare[1][2][3].