Does tapeworm become resistant to treatment?

I rescued a cat in January. After a month or so I noticed tapeworms, I brought the segments in and the vet verified it and treated him. He was treated by the rescue organization also. He was clear for a couple months, now I am finding segments again. He has never been outside since I've owned him and there has never been fleas on him or in my home either. Nor are there any rodents in my home that could be carrying them. The only thing I can think of is that the parasites have built up a resistance to the treatment over the course of time. Is this possible? Is there any possible way to rid him completely and permanently?