Antibiotic Overuse, Implications on the Human Gastrointestinal Tract, and Links to Autism Spectrum Disorder: A Clinical Survey

Background: The autism spectrum disorder (ASD) diagnosis has been on a steady rise over the past few decades, and yet the mechanisms behind its pathology are still largely unknown. In individuals with an ASD diagnosis, gastrointestinal (GI) symptoms are among the most common medical co-morbidities. Studies have found that GI symptoms occur in nearly half of children with ASD, and the prevalence of GI symptoms increases as children get older. In ASD individuals, an alteration in gut microbiota has been demonstrated. This dearth of the GI microbiome in autism might also be exacerbated by the over-prescription of antibiotics.

Objectives: There is currently a literature gap in the link between antibiotic overuse, related GI dysfunction, and the development of ASD. Our pilot study aims to investigate whether there is antibiotic overuse in ASD subjects that can lead to GI distress.

Methods: The frequency of antibiotic use in twenty children with an autism diagnosis was compared to the antibiotics use in twenty neuro-typical children. Parents of all participated children were surveyed using the same questions.

Results: Children in the ASD diagnosis group were given more than double the amount (rounds) of antibiotics as the children in the neuro-typical group; the ASD group had 94 rounds of antibiotics prescribed, while the neuro-typical group had 41 . The median for the number of rounds of antibiotics in the ASD group was 4 rounds with an IQR = 2-6 rounds, while the median in the control group was 2 rounds with an IQR=1-3 rounds. There was also a different in the length of time that the ASD group took antibiotics vs. the neuro-typical controls. In the neuro-typical cases, the typical duration was between 7 to 10 days while parents from the ASD group reported antibiotic durations ranging from weeks to months of use at one stretch of time. The median length of time for the ASD group was 10 days with an IQR = 7-10 days, while the median for the control group was 7 days with an IQR = 7-8.5 days. Out of the 20 children in the ASD group, 17 (85%) reported incidence of GI distress, versus 3 out of 20 (15%) in the neuro-typical group. A Fischer Exact Test yielded a p value of <0.001. These results indicate that the increase in the incidence of GI distress is statistically significant in children with ASD as compared with neuro-typical children.

Conclusions: The results of this work suggests that the overuse of antibiotics in early childhood can be a risk factor for the development of ASD. This is a significant finding, as this tremendous amount of antibiotic use likely drives GI inflammation and reduces local flora. Understanding the risk factors involved in predisposition to ASD will provide novel insights into the pathophysiology of this neurological disorder and will pave the way for developing novel treatment modalities in pursuit of improving quality of life of ASD individuals and their families.