Our antibiotics are failing us. Bacteria are evolving resistance to virtually all of our frontline drugs. They build up mutations in their DNA that allow them to pump drugs from their cells, or build enzymes that destroy them. They shift into stealth mode, by changing the shape of the molecules that antibiotics are designed to target.

This is the standard story of how microbes foil antibiotics, and it’s incomplete. Some bacteria can withstand an antibiotic assault without any special defences. They just keep their heads down.

All of our antibiotics have been designed to kill bacteria that are actively multiplying, like jamming a spanner into a whirring machine. If the machine is still, if no wheels or cogs are turning, the spanner