The United States has found the first case of bacterial infection resistant to all known antibiotics. If this superbug spreads, it may pose a serious risk of daily infections. This superbug itself is first infected with a small DNA molecule called a plasmid, which carries a gene called mcr-1 that can develop resistance to colistin. Colistin is an antibiotic specifically used to combat "nightmare bacteria". The picture shows the Escherichia coli carrying the mcr-1 gene under the microscope.