Every living thing on the planet plays host to viruses, and bacteria are no exception. Bacteriophages—or just “phages” to those in the know—are the viruses that attack bacteria. And we are in dire need of things that attack bacteria, since many pathogenic bacterial species have developed resistance to the antibiotics we’ve been throwing at them for decades.
Phage therapy is attractive not only because of the issue of antibiotic use yielding antibiotic resistance, but also because it can be targeted specifically to the bacteria that are causing an infection. Most antibiotics currently in use are rather broad spectrum, so they obliterate many of the bacteria they encounter, including the ones we need that are happily residing in our guts, minding their own business and not causing anyone any problems. Phages can be more precise.
But is phage therapy actually effective? A new study suggests it may end up being undercut by our own immune systems, which treat the therapies like a hostile invader.