Persistent bacterial bronchitis degrades pulmonary microbiota

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Persistent bacterial bronchitis (PBB) is associated to a high risk of progression to chronic bronchitis in young children, particularly in preschoolers. It also impacts the composition and diversity of the airway microbiota. This discovery, made by a team of British and Australian researchers, could facilitate diagnosis and improve therapeutic strategy.

 

Persistent bacterial bronchitis poses diagnostic challenges: it is sometimes misdiagnosed as asthma or recurrent viral infection. The other issue lies in the consequences of the disease on the bronchial microbiota, whose composition and diversity seem to play a protective role in certain broncho-pulmonary disorders. To elaborate on the subject, the researchers analyzed the microbiota in bronquial protected brushings from 24 children with PBB and 20 healthy controls.

Improvement in sampling methods, decrease in microbial diversity

This study had two main objectives: the first was to identify potential perturbations in the pulmonary microbiota of children with PBB; and the second was to demonstrate that obtaining brush samples through an endotracheal tube was just as effective as bronchoscope guided sampling (which is a more invasive technique). This second “technical” objective was completed since similar microbial populations were detected with both sampling methods. This will help minimize invasive procedures in young patients. Regarding microbiota composition, 16S rRNA sequencing revealed a decrease in bacterial diversity and a change in composition. The team identified that, in patients with PBB,  microbial communities were dominated by Proteobacteria, and found a significant correlation between PDD and Haemophilus and Neisseria. This suggests that persistent bacterial bronchitis disrupts the airway microbiota. These results are the first step to better understand the role of the airway microbiota in order to facilitate diagnosis and limit disease impact and progression.

From traditional culture techniques to next generation sequencing methods

It should be noted that thanks to the method used in this study, the researchers made an interesting finding: some strains identified by sequencing, such as Neisseria, were not detected by the more traditional culture techniques. Although many Neisseria species are considered as non-pathogenic, they colonize the nasopharyngeal mucosa and have been implicated in cases of pneumonia, COPD* and periodontal diseases. The authors thus highlighted the limitations of current diagnostic procedures—the results of which typically dictate therapeutic strategies—and demonstrated that the microbiota is an essential tool to prevent relapses and limit disease progression.

 

*COPD: chronic obstructive pulmonary disease

 

Sources:

L. Cuthbertson, V. Craven, L. Bingle, et al. : The impact of persistent bacterial bronchitis on the pulmonary microbiome of children. PLOS ONE, 27 décembre 2017.