I am a huge fan of grain fermented kefir. I drink at least six ounces of the stuff every day. And while I believe kefir has greatly improved my overall health, I do not believe any of the many organisms in the kefir have successfully implanted in my intestines. As it has been noted before, it could be that implantation is particularly difficult for a large percentage of candida sufferers. This resistance to implantation could even be based on genetic factors.
I have moved on to "super strains". These strains, usually patented, have been selected for their superior resistance to stomach acid and bile. Many of these "super strains" also exhibit a vastly increased capacity for colonization.
I am not ready to declare success with the "super strains".