Sample size of 18? I'm throwing the BS flag on this play.

Amazing and had a suspicious feeling this was a causative factor,these folks need to do a thorough blood screening of cellular sized bacteria .That may be causing additional long term difficiancies in immu icological function. That may have attached themselves to DNA strand.
Perhaps stem cell modification of genome may be in order. LOL Your welcome.

How about this theory - the autstics gut flora lacks bacteria to break down oxalates both from food and from yests in gut. A leaky gut caused by antibiotics allows the oxalate chrystals in to the blood and they irritate the brain.

@DavidMiles
This appears to be an early-stage proof-of-concept trial that has built on previous observations in animal models. I'm sure there are at least a few, but the one I'm thinking of was conducted in 2013 on mice showing fascinating results: http://dx.doi.org/10.1016/j.cell.2013.11.024
I'm glad to see this potential treatment finally reaching testing stages in humans, and am excited to see where it will go next.

The key-element is this : "...likely due to their being put on antibiotics early in life."

If there is correlation found here, then maybe we should examine the time frame when doctors were more likely to give certain types of antibiotics to infants. Or the fact the amoxicillin took the place of penicillin in the early 80s. Besides better identification of autism, it does still seem possible that something changed that raised the rate of autism. I know that hyperactivity has been tied to tonsils and sleep clinics are now filled with kids with apnea-lite. They take out the tonsils and the kids are off of Ritalin. Being overtired from apnea was essentially the cause of hyperactivity. The one I go to sometimes has more kids than adults for sleep studies.

I understand that well over half of the neurons in our bodies are in our gut - could this be the reason for the success?

I wouldn't say it was totally due to antibiotics in early life, my son is on the spectrum and has never been given antibiotics nor a single vaccine...he does however have a very limited diet, obviously that is a big contributing factor toward lack of bacterial diversity.

What a great research study! Imagine a child with gut problems; that would cause irritable behavior

Hmmm ... I wonder if this could have a positive effect on the various types of anxieties?