Children who are exposed to antibiotics before the age of one are more than twice as likely to develop asthma claims new research from the University of Manchester.
While scientists are still uncertain of the exact cause of asthma, it had been thought that antibiotic use in infants affected the intestinal bacteria known as gut flora leading to changes in the child’s immune system and increasing susceptibility to allergic asthma later in life.
The new findings, however, indicate that impaired viral immunity and genetic variants on chromosome 17 cause an increased risk of both antibiotic use in early life and later-life asthma rather than the antibiotics themselves.
The study’s results also show that children who experienced wheezing who were treated with an antibiotic before their first birthday were 50% more likely to experience severe wheeze or asthma exacerbations and be hospitalised for asthma later on.
Lead author, from the Institute of Inflammation and Repair of the University of Manchester, Professor Adnan Custovic said: “Asthma is the result of chronic inflammation of the airways which subsequently results in increased contractability of the surrounding smooth muscles.
“This among other factors leads to bouts of narrowing of the airway and the classic symptoms of wheezing. The narrowing is typically reversible with or without treatment.”
Charity Asthma UK claims the illness affects more than five million people in the UK with a potentially life-threatening asthma attack affecting someone every 10 seconds.
The University of Manchester researchers examined data from the Manchester Asthma and Allergy Study (MAAS) – which has followed over 1000 children from birth to 11 years.
Information on antibiotic prescriptions, wheezing and asthma exacerbations were taken from medical records, while skin reaction tests that show whether a child is hypersensitive to allergens were done at ages three, five, eight and 11 years of age.
At age 11, blood was collected from children who had received at least only one course of antibiotics or no antibiotics in the first year of life to compare their immune-system cell response to viruses and bacteria.
Viruses, such as rhinovirus, which is responsible for the common cold and the respiratory syncytial virus were tested as well as bacteria like Haemophilus influenza and Streptococcus pneumonia that can lead to meningitis or pneumonia.
Genetic testing was also done to look at the links between common genetic variations on chromosome 17, known as 17q21, and antibiotic prescriptions.
The study showed that these children showed significantly lower induction of cytokines, which are the bodies’ key defence against virus infections such as the common cold.
Professor Custovic said: “We speculate that hidden factors which increase the likelihood of both antibiotic prescription in early life and subsequent asthma are an increased susceptibility to viral infections due to impaired antiviral immunity and genetic variants on 17q21.
“However, further studies will be needed to confirm that the impaired immunity was present at the time of the early childhood respiratory symptoms and predated antibiotic prescribing rather than as a consequence of the antibiotics.”
Image courtesy of NIAID with thanks
