A superbug may be bacteria, viruses, parasites or fungi. Superbugs can't be stopped by medicines that are the first choice for treating diseases these germs cause. Superbug infections can lead to higher rates of death from otherwise treatable diseases.

The bacteria that cause disease are remarkably resilient and can develop ways to evade the drugs meant to kill or weaken them. This phenomenon is called antibiotic resistance and it is due largely to the growing, and often careless, use of antibiotics.