I had miserable UTI's a number of years ago - awful, I have never been in such pain in my life. The tests would often come out negative because of how much water I guess I was drinking. I was told by two different people (a friend of mine who was a nurse and one other person) to cut down on my sugar and that might help. After months and months of UTI's, cutting down on sugar ended them and I've not had any more. If I ever feel just a little like it might be happening again, I cut down again even further and drink some water. It seemed weird that no doctor told me that, but that really did it for me.