In 2010, when Lilli Holst scraped a lump of soil from the underside of a rotting eggplant, she had no idea that this act would help to save the life of a British teenager, eight years later and 6,000 miles away.
Holst, an undergraduate at the University of KwaZulu-Natal, in South Africa, was participating in a project in which students search through local soil samples for new phages—viruses that infect and kill bacteria. Holst found several, and gave them all names. In a worm farm, she discovered Liefie. In an aloe garden, Lixy. And from that decaying eggplant, Muddy. All three viruses infect a common bacterium called Mycobacterium smegmatis. And all of them were new to science.
Samples of Muddy and the other phage viruses made their way to the lab of Graham Hatfull, a phage expert at the University of Pittsburgh. He stored them in a freezer, along with at least 10,000 others that had also been discovered and named by students: Mariokart, TGIPhriday, Chupacabra, Benvolio, ChickenNugget, IAmGroot, and more. They were sitting there, in the cold, when in late 2017 Hatfull got a call from doctors at Great Ormond Street Hospital, in London.
The London team, led by the pediatrician Helen Spencer, had been treating a 15-year-old girl with cystic fibrosis—a genetic disorder that leads to persistent lung infections. To prepare for a double lung transplant, the girl had been taking drugs to suppress her immune system, and these allowed an already present microbe called Mycobacterium abscessus to run amok through her body. She had new lungs, but also heavy infections in her liver, limbs, buttocks, and torso, and in the surgical wound on her chest. Antibiotics weren’t working, and the outlook was grim. The team put her on a palliative-care plan.