Melbourne researchers have pioneered a new approach to killing bacteria that has become resistant to antibiotics. Scientists at Monash University, the University of Melbourne and the Walter and Eliza Institute have used a locally developed experimental cancer drug to prevent infections from spreading in the body.

The drug effectively causes the body's immune cells known as macrophages – which translates as ''big eaters" – to commit suicide, and take out the infection before it has a chance to multiply.

Coloured scanning electron micrograph of a macrophage white blood cell (red) engulfing a tuberculosis (Mycobacterium tuberculosis) bacterium (yellow). Credit:Science Photo Library

Macrophages ordinarily consume and kill infectious bacteria in a process called phagocytosis. But some bacteria – including legionella, which is naturally resistant to some antibiotics – have evolved to take over the macrophage, and use it as a host where they breed. The bacteria then kills the immune cell, takes over other macrophages and the cycle continues until the body is fully infected.

Lead researcher Dr Thomas Naderer, from the Monash University Biomedicine Discovery Institute, said that because the bacteria are difficult to kill with drugs once they have been consumed by the immune cell, ''we decided to focus on the host cell, the macrophage, and see if there was a way to program it to commit suicide."