What makes you think there exists a way to fight that isn't harmful the host. Antibiotics work by stopping some biologicial pathway - there are only so many of those in bacteria, you can stop them at any point of course, but you have to stop it. However most of those pathways are also in other lifeforms and so stopping the pathway means you kill not only the bacteria but also human/mushroom.

We have been lucky that we have found a few pathways that are not in human (read mammals) that are in bacteria we worry about. However bacteria just finds a different pathway and odds are that is a pathway in humans and so we can't use it because it would kill humans as well.