What kills more living things than anything else? A bacteriophage is not a bacteria; it's a virus that kills bacteria. As a virus, it walks the line between living and non-living. It kills trillions of bacteria every day. However, we are now looking at bacteriophages as something we can use for our own ends. Kurzgesagt explains bacteriophages to us.
Phage therapy to fight superbugs is not FDA approved, so very few patients in the US have the treatment, and they must get a compassionate waiver to even try it. Read about one such patient -who happened to be married to an infectious-disease epidemiologist, in an article at Mother Jones.