Genetically modified virus saves teen's life

Isabelle Carnell-Holdaway, 17, has cystic fibrosis, and has also been fighting a recurring infection by antibiotic-resistant bacteria since she was 8.

Jo Carnell-Holdaway told reporters that Isabelle underwent a lung transplant in 2017 that was "uncomplicated," but the teen had to stop using an antibiotic that caused severe side effects. Her bacterial infection then came back.

By 2018, she was in intensive care with acute liver failure.

Desperation led her family and medical care team to look to something called "phage therapy."

Bacteriophages or "phages" are viruses that can infect and destroy bacteria.

Doctors created a phage cocktail for Isabelle, including one phage that was genetically-modified to kill the target bacterium more effectively.

Isabelle has even recovered enough to return to school and have a weekend job.