[bhickey]

I don't think they're overstating this claim. It's a double-edged sword.

If you have an infection your doctor can give you antibiotics and send you home. Antibiotics tend to be wide spectrum and kill entire classes of bacteria, like gram-positive, indiscriminately.

A phage that kills one strain of E.coli might be completely incapable of infecting a closely related E.coli strain. Thinking that a single phage could be effective against closely relate pathogens, for example E.coli AND Salmonella, is wishful thinking. This might have the upside of preserving gut flora, but it's easy to see how it would confound treatment: some things are very difficult to grow in vitro.