He Was Dying. Antibiotics Weren’t Working. Then Doctors Tried a Forgotten Treatment.
Phages are making a comeback.
...phages do not kill indiscriminately: Though there are trillions in the world, each is tuned evolutionarily to destroy only particular bacteria. In 1917, Félix d’Herelle recognized phages’ talent for targeted killing. He imagined that if he could find the correct phages, he could use them to cure deadly bacterial infections...
https://www.motherjones.com/environment/2018/05/the-best-viral-news-youll-ever-read-antibiotic-resistance-phage-therapy-bacteriophage-virus/