The alarm bells sounded on November 18, 2015. Antibiotic resistance is usually a slow-moving crisis, one of the reasons its danger can be hard to convey. One by one, over the years, the drugs used to fight the most stubborn infections have fallen by the wayside as bacteria have evolved resistance to them. For certain infections, the only drug left is colistin. Then on November 18, 2015, scientists published a report in the British medical journal The Lancet: A single, easily spreadable gene makes the bacteria that carry it resistant to colistin, our antibiotic of last resort.