Antibiotics are the most common prescription drug given to children, and a third of such prescriptions are not necessary. This would not necessarily be a cause for concern, except that antibiotics disrupt gut microbes, imbalances in which are linked to disease in later life, say researchers after reviewing current knowledge linking antibiotic use in infants, imbalance in gut microbes and adult disease.
Evidence of the potential harm to emotional and physical health caused by imbalances in gut microbes - called dysbiosis - is mounting daily. Dysbiosis has been linked to infectious diseases, allergies and other autoimmune disorders, and even obesity, later in life.
For instance, recently, there was a report on how gut microbes are important for the production of serotonin, a brain chemical traditionally associated with regulation of emotions and behavior, but where imbalances in production outside the brain are now also linked to diseases ranging from irritable bowel syndrome and cardiovascular disease, to osteoporosis.
Writing the journal Cell Host & Microbe, the researchers behind this new study - including members from the University of Minnesota in Minneapolis - highlight the complex nature of the connection between how microbes in the infant gut react to antibiotics and the development of disease later in life.
Senior author Dan Knights, an assistant professor specializing in computational biology at the University of Minnesota, says:
"Diseases related to metabolism and the immune system are increasing dramatically, and in many cases we don't know why."
Framework for studying antibiotic-related dysbiosis in children
To make it easier to navigate their synthesis of current knowledge, the team created a framework that can be used to study antibiotic-related dysbiosis in children. Prof. Knights explains:
"Previous studies showed links between antibiotic use and unbalanced gut bacteria, and others showed links between unbalanced gut bacteria and adult disease. Over the past year we synthesized hundreds of studies and found evidence of strong correlations between antibiotic use, changes in gut bacteria, and disease in adulthood."
The framework is depicted at Figure 1 in the Cell Host & Microbe paper.
For example, in the case of allergies, they found use of antibiotics may destroy communities of gut bacteria that help immune cells mature. Even if these colonies return, the immune system remains impaired.
In relation to obesity, they found antibiotic-induced imbalances in gut microbiota led to increased levels of short-chain fatty acids that affect metabolism.
The team also showed how you can predict an infant's age to within 1.3 months from the maturity of their gut microbiota. This discovery could lead to a test and treatments for children whose microbiome is underdeveloped because of antibiotic use, or other reasons.Prof. Knights concludes:
"We think these findings help develop a roadmap for future research to determine the health consequences of antibiotic use and for recommendations for prescribing them. The clinical test we demonstrated would also allow us to think about interventions at an early age."
He and his colleagues call for more research into four areas of antibiotic-related dysbiosis in children: loss of key populations, loss of diversity, effect on metabolism and overgrowth of potentially harmful bacteria.
They also say there is a need to form a large and diverse cohort of children to establish a baseline for healthy microbiome development.
Such a baseline cohort is "essential to advancing diagnosis, interpretation, and eventual treatment of pediatric dysbiosis," they urge.
Meanwhile, another recent study shows how gut microbiome diversity appears to be diminished by Western lifestyles. There, researchers compared the gut microbiomes of people living in Papua New Guinea with people living the US. They found 50 bacterial types in Papua New Guinean microbiomes were missing in the US ones.