Researchers demonstrate that a bacteria can be modified to act as ‘living medicine’ in the lung. The treatment significantly reduced acute lung infections in mice and doubled their survival rate. It showed no signs of toxicity in the lungs and once the treatment had finished its course, it was cleared by the immune system in a period of four days. The treatment also cleared biofilms that accumulate on the surface of endotracheal tubes used by patients with ventilator-associated pneumonia, which is one of the leading causes of mortality in intensive care units. The study paves the way for researchers to repurpose the bacteria to treat other types of lung diseases such as cancer, asthma or pulmonary fibrosis.