A 15-year-old girl with cystic fibrosis who suffered from an antibiotic-resistant mycobacterium infection has been treated thanks to a "modern" therapeutic approach, phage therapy. Not so modern actually, given that the first experiments date back to the 20s of the last century. But it has only recently been rediscovered and proposed as a valid alternative to antibiotic therapy, especially in the case of resistant bacteria, which are going to become more and more threatening.