I subsequently contacted Dr. Sydney Finegold and received the following response:
I think fecal transplant may well work in
autism, but there have been no trials. People doing fecal transplants
like to have a close relative as a donor because they are much less
likely to have dangerous viruses such as HIV and hepatitis viruses.
People are working on making a "synthetic" stool made by growing all
the bacteria separately and then mixing them together. This may be the
best answer, but it isn't ready yet.
Searching online brought me to your experience. Both of our boys (age 7 and 5) have been diagnosed with mild autism. I have not been diagnosed but appear to have symptoms of Asperger's. We have not experienced severe bacterial problems, but do have irritable bowel syndrome and food sensitivities.
I look forward to reading more about your experience.