But what if your UTI isn’t caused by E. coli? What if it’s caused by Klebsiella or some other infection? Then D-mannose won’t work, and you’re left still dealing with pain and symptoms. Maybe the D-mannose worked at first, but then the UTI reoccurred. That means the immune system couldn’t keep the infection down. And that’s where testing comes in. If it keeps coming back, you need to look deeper to see what else is out of balance in the body. | Dr. Patrick Flynn