In my case, after taking Bactrim to get rid of the Blastocystis, apparently the Blasto was eradicated (lab test results were negative) but still a lot of upheaval in the GI tract with relapses of yellow, watery diarrhea, anal itching, rash, swelling, gassy episodes (I presume it was yeast/dybiosis)C Dif came back negative ... the ONLY thing that worked to bring about control and normal BM's were probiotics and lots of them in varying doses along with kefir/yogurt. I will be eternally grateful to probiotics for rescuing me from the nightmare aftermath the Antibiotic left me with. They are a precious as gold and well worth the money spent on them.