It's not being 'broadened to include bacteria as well' at all. And there are hundreds of different studies like this. The same results are found over and over. And you also have to ask yourself if it's NOT bacterial why are these antibiotics working against it? Every single case of bad equine thrush, for decades more than you have been alive, vets have been having us treat them with antibiotics. Vets have been having us put antibiotic products on equine thrush for a very long time now. Why? Because it works. And if a broader spectrum antibiotic doesn't knock it out they switch to one more specific to that bacteria.