This is correct, it's called empiric treatment. If a patient comes in with altered mental status and neck rigidity, you don't have time to take a lumbar puncture and culture bacteria. I don't know anything about phage treatment, but from what the other commenter said, it seems like then you'd have to do some sort of PCR test as well. You simply don't have time for any of that -- your only choice is to blast them with vancomycin + ceftriaxone.

Yeah, which is why we need to stop using antibiotics for cases where we could use phage treatment.

Wait what

If you come into ED with GGP's symptom's, you might only have an hour to live. Hopefully for you it's bacterial and didn't pick up resistance from horizontal transference from a strep throat treatment that's trivial to culture and, while unpleasant, can wait a few hours to start treatment while the correct bacteriophage is readied.

Feels like it might be more practical to simply distribute phage therapy to a whole population targeting a known pathogen, like this year’s cold strain. Especially of the goal is just to reduce the use of antibiotics, not eliminate.

"Common cold" is a virus. Vaccines train your immune system to fight things.

Bacteriophages fight bacteria. They actually do the fighting. They are quickly cleared by the body, so they are useless for prevention.