A parent has been prompted to investigate the connections between gut bacteria and autism following surprising improvements in his son's autism while taking an antibiotic for strep throat.

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Amoxicillin is a form of penicillin and is frequently used to treat bacterial infections such as bronchitis, pneumonia and tonsillitis.

John Rodakis' son was prescribed a 10-day course of amoxicillin, one of the most frequently used antibiotics in the US, and within just 4 days of commencing the treatment, changes were observed in his autism symptoms.

"[He] began making eye contact, which he had previously avoided; his speech, which was severely delayed, began to improve markedly; he became less 'rigid' in his insistence for sameness and routine; and he also displayed an uncharacteristic level of energy, which he had historically lacked," explains Rodakis.

In an article published in Microbial Ecology in Health and Disease, Rodakis describes this unexpected turn of events and the journey of discovery he has since embarked upon, as he attempts to understand what caused his son's symptoms to change.

It became apparent to him early in his investigation that many other parents had experienced similar changes following courses of antibiotics, with some even routinely giving their autistic children antibiotics in order to improve their symptoms.

As well as these positive experiences, Rodakis also notes that some parents found their children's symptoms worsened under the influence of the medicine. "In my view, these stories are not contradictory but rather reinforce the notion that an antibiotic can create an effect in autism," writes Rodakis.

Rodakis' investigation brought him into contact with Dr. Richard Frye, head of the Autism Research Program at Arkansas Children's Hospital Research Institute. Together, in collaboration with other researchers from across the world, they decided a research trial was required, and a scientific conference was warranted.

Could research into the 'gut-brain' connection reveal the core biology of autism?

"Careful parental observations can be crucial," Dr. Frye explains. "In science we take these observations, put them through the scientific method, and see what we find. This is what can lead to ground-breaking scientific discoveries and breakthroughs in the field."

The First International Symposium on the Microbiome in Health and Disease with a Special Focus on Autism was held in June and it has led to a special edition of Microbial Ecology in Health and Disease being published, focusing on autism and the microbiome.

In recent years, evidence associating the microbiome - the collection of micro-organisms living on and in the human body - with autism has grown sharply.

Ellen Bolte, another parent of a child with autism spectrum disorder, had a hypothesis in 1999 that some cases of autism were affected by gut bacteria. From this hypothesis, a small clinical trial was conducted and since then, a significant body of research has been compiled.

One of the speakers at the conference, Dr. Rosa Krajmalnik-Brown, led a team of researchers at Arizona State University for a study in which children with autism were found to have less diversity in their gut bacteria than typically developing children. This link between the microbiome and autism is referred to as the "gut brain" connection.

Rodakis believes that antibiotics may be useful as a research tool and could lead to the development of future treatment methods for his son. "I was determined to better understand this phenomenon because I believed that if we could understand the biological basis of his improvements, we might gain insight into how autism works and be able to help him," he explains, adding:

"Current research is demonstrating that gut bacteria play previously undiscovered roles in health and disease throughout medicine. The evidence is very strong that they also play a role in autism. It's my hope that by studying these antibiotic-responding children, we can learn more about the core biology of autism."

Previously, Medical News Today reported on a study of preschool children that identified different trajectories for autism spectrum disorder, observing changes in symptom severity and adaptive function over time.