Airway microbiota modify azithromycin effect in children with recurrent asthma symptoms

In a new study, airway microbiota composition was associated with duration of acute episodes of asthma-like symptoms and the effect of azithromycin treatment in young children.

“Recurrent episodes of asthma-like symptoms in young children have traditionally been believed to be triggered by viral infections, but recent studies have shown that bacteria may also play a role,” Jonathan Thorsen, PhD, senior scientist in the Copenhagen Prospective Study on Asthma in Childhood (COPSAC) at Harley and Gentofte Hospital and postdoctoral research fellow at the Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark, and colleagues wrote in the American Journal of Respiratory and Critical Care Medicine. “The macrolide antibiotic azithromycin has a beneficial clinical effect in such episodes, but the underlying mechanism is unknown.”

Researchers evaluated 139 airway microbiota samples from 68 children (mean age, 1.98 years; 66.2% boys) from the COPSAC 2010 cohort. All children had recurrent asthma-like symptoms and were randomly assigned to azithromycin or placebo during acute asthma episodes from November 2010 to January 2014. Before being randomly assigned, researchers obtained hypopharyngeal aspirates that were examined by RNA gene amplicon sequencing.

After randomization, asthma episode duration was associated with microbiota richness, with a 7.5% increased duration per 10 additional operational taxonomic units (P = .025). In addition, asthma episode duration was also associated with 15 individual operational taxonomic units and microbial pneumotypes, according to the results.

Treatment with azithromycin reduced asthma episode duration by 43%, with a median duration of 4 days after randomization (P = .005). Before treatment, microbiota richness increased azithromycin effect by 10% per 10 additional operational taxonomic units. More operational taxonomic units were positively associated with increased azithromycin effect (82 vs. 58; P = .0032), according to the results.

Researchers observed effect modification of azithromycin for five individual operational taxonomic units; Veillonella, Leuconostoc and Vibrio increased the effect and two Neisseria operational taxonomic units decreased the effect.

There was no significant effect interaction between pneumotype and treatment (P = .67).

“These findings underscore the importance of the airway microbiota in young children with recurrent asthma-like episodes and substantiate the observed effect of antibiotic treatment in these patients,” the researchers wrote.