According to a booklet I used to have on D. Mannose, it only works if your infection is caused by E. coli. They said that 90% of bladder infections are caused by E. Coli. If it is caused from some other organism it won't work. I too, have used d. mannose for years. When it works, it works very well, but other times it has no effect. On those times, I've went in and had a urine culture done and every time it was a different organism.
Another treatment I've tried with some success is uva ursi and barberry tea. Bring eight cups of water to a boil. Add 1 tablespoon of ground barberry, and 2 tablespoons of ground uva ursi. Simmer on low for 45 minutes. Divide into 3 doses. Take 1 in the morning, one in the afternoon, and one before you go to bed. I'm won't lie to you this concoction is very bitter and I usually have to dilute each dose with an extra 8 oz. of water to choke it down. You should also take 200 mg. of potassium and 250 mg. of magnesium with each dose. The active ingredients in these herbs are more effective in an alkaline environment, so you want to alkalize, rather than acidify your urine when taking these herbs. Of course when you're drinking this stuff you also want to be taking lots of extra water. The tea is a natural diuretic and will make you very thirsty.