I'm not sure that Florastor prevents c diff, but I do think that it helps prevent a relapse of a c diff infection. Apparently the yeast in Florastor competes with the c diff for nutrients, and if you are prone to c diff infections, this will help you to avoid another one. Another thing I like about Florastor is that it is safe to take with antibiotics. If you are going to take Florastor for an extended time, take a look into buying them off of eBay. You can get three boxes of 50 (or is it 60?) caps for less than $100, and that includes shipping costs. I'd probably still be taking Florastor except the VSL#3 has been helping me quite a bit. I can't afford two high end probiotics.
Good luck with the new pro-bs. Hopefully you'll be able to stay med free and in remission.
36 y.o. male
Diagnosed w/ UC in May '06, had symptoms since '99
Meds & supplements: VSL#3, Lialda, Allegra, multi-vitamin, Wellbutrin XL, Prednisone, fluoxetine, flaxseed oil, magnesium, and vit B-12.