Anecdotal evidence and case reports had suggested that the problem wasn't so much the presence of C. diff as the fact that it had grown out of balance with the rest of the gut's bacterial ecosystem. To get the gut back into balance, fecal transplants had been tried and, anecdotally at least, they worked. So some doctors in the Netherlands decided to do a clinical trial, comparing a fecal transplant to standard care with vancomycin. The trial was what the researchers called "open label," meaning that people were aware they were having a feeding tube stuffed down their nose to deliver someone else's poop into their body.
http://arstechnica.com/science/2013/01/fecal-transplants-cure-diarrhea-modulate-testosterone-levels/