Not sure exactly what you mean by sterile. Septic means that the infection has spread throughout. Sterile means the absence of bacteria or infection. I have never heard of sterile EYP.I wonder if the only way to tell if it's septic EYP vs sterile?
In the best case scenario it would be that your hen reacts well to the antibiotics. The infection clears. Then... you have to deal with her laying eggs. If after a bout with EYP she becomes sterile meaning unable to lay eggs again (like a sterile woman can’t have children) then that would truly be the best case scenario because the cycle would not keep repeating. And the antibiotics cleared the infection. Make sense?