Hospital superbugs may be spread by the dirty hands of doctors and nurses that act as germ "superspreaders".

Researchers created a mathematical model of a hypothetical intensive care unit (ICU) with a staff of 22. They found that staff who saw all patients briefly were better at spreading germs than those who tended a few patients very closely. If just one of the former always failed to wash their hands, it caused more infections than if the entire staff forgot one-quarter of the time.

Hospitals use the consumption of hand-hygiene products to monitor hand-washing. The study suggests individual surveillance of hand hygiene would be better.