I have had many cultures that have been negative. These were done on the same urine that was examined, and it was pronounced that I had a bad bladder infection. My urologist thought I had IC, possibly along with intermittent infection. It was very useful to get a cystoscopy procedure done. You can see on the screen what the inside of the bladder looks like. In my case there was no ulceration or inflammation typical of IC. The urologist changed his diagnosis after looking at the inside of the bladder. He still doesn't know why I am not able to get rid of the symptoms, but at least I don't have to treat for a condition I don't have, and one which doesn't offer a hopeful prognosis.
You can also try Prelief, and see if that helps. Also, write down a log of your day--what you eat, what you do, how you feel. See if you can notice some patterns associated with the rise and fall of symptoms. I discovered eating regular meals is very helpful, for instance, but I don't know why. I try to put all the things together that have a pattern of helping the symptoms, and removing all that aggravate them. Your doctor can instill injectable antibiotics, or anti-inflammatory substances into your bladder. Sometimes one antibiotic will work, whereas another one will not. In my case, the anti-inflammatory treatment had no effect, while the Neosporin instillation did. Later, the Neosporin quit working, presumably because the bacteria developed immunity to it, but Gentamicin worked like a charm. There are about five of these injectable antibiotics that can be instilled into the bladder. Usually, the bacteria are not immune to these since the antibiotics usually taken by mouth have had more exposure.
