Study finds biofilm link to persistent wet cough in children

Jolyon Attwooll

2/02/2022 4:53:12 PM

Researchers hope the findings may lead to more effective treatments for protracted bacterial bronchitis and bronchiectasis.

Child with stethoscope on chest
While some children respond to antibiotics, others have repeated episodes of bronchitis that never seem to improve. (Image: Getty Images)

Researchers believe they may have pinpointed why chest infections recur in some children, causing them greater risk of developing the chronic respiratory condition bronchiectasis.
In a new study published in Lancet Microbe, researchers describe starting with the hypothesis that biofilm could be behind the mixed results of antibiotic treatment for children with protracted bacterial bronchitis (PBB) and bronchiectasis.
According to those involved in the collaboration between Menzies School of Health Research, the Telethon Kids Institute and the University of Western Australia (UWA), there had previously been ‘scant data’ to support the theory.
‘We know that for most kids with PBB, their cough will get better after they have had a two-week course of antibiotics, but we also know that some kids will have repeated episodes of bronchitis that never seem to get better,’ lead author Dr Robyn Marsh said.
‘We know that chest infections can lead to PBB and bronchiectasis, but the reasons why only some kids respond to antibiotics isn’t always clear.’
As such, they set out to investigate biofilm presence in children affected by PBB and bronchiectasis and found what they call a ‘significant’ association between lower airway biofilms and signs of infection.
The researchers say their work provides more evidence biofilm plays a role in chronic infective lung diseases, and could also help explain the varying effectiveness of antibiotic treatments.

‘Our finding that lower airway biofilms are prevalent, but not ubiquitous, among children with PBB or bronchiectasis is consistent with the variable treatment responses reported for these populations and indicates that anti-biofilm therapies might be beneficial for some children,’ the authors write.
The researchers used samples collected by bronchoalveolar lavage, in which a sterile solution is used to flush the child’s airways, to test for biofilm.
Specimens from 144 children recruited for observational studies of chronic wet cough at the Royal Children’s Hospital in Brisbane and the Royal Darwin Hospital were collected between 2011 and 2014.
Using a powerful microscope, they also found biofilm prevalence was significantly higher among children with bronchiectasis than children with PBB.
‘Higher prevalence of upper airway biofilms among those with bronchiectasis points to a previously underappreciated role for microaspiration as a driver of this disease,’ they wrote.
Researchers believe the findings should direct focus on the nasal and oropharyngeal health of children with bronchiectasis ‘to understand whether novel interventions focused on the upper airways could be useful to improving long-term clinical outcomes’.
Professor Anne Chang, Head of Child Health at Menzies School of Health Research, says the study could prompt more effective ways to treat affected children.
‘We’ve suspected these children have biofilm-associated infections for a while but until now, no one has proven it,’ Professor Chang said.
‘Now that we’ve seen it, we can start investigating new ways to treat these children so that fewer of them will progress to having severe lung disease.’
Dr Kerry Hancock, Chair of RACGP Specific Interests Respiratory Medicine, welcomed the study’s findings.
‘It is exciting and important research that will contribute to the knowledge base of PBB and why some children go on to develop bronchiectasis … a very serious lung disease that will have a lifetime impact,’ she told newsGP.
‘My message to my GP colleagues is to be on the lookout for those children who have PBB, manage them according to guidelines and arrange referral to specialist services if [they are] not responding as expected so they can be further investigated and monitored.’
PBB is common among children, with the authors of the Lancet study saying it is found in up to 40% of children referred to a specialist with a persistent wet cough.
It is clinically diagnosed when children have a wet cough for more than four weeks, do not have signs of other causes of cough, and respond to oral antibiotic therapy within 2–4 weeks.
According to the study, antibiotic treatments work in most cases. However, the authors suggest up to 44% of affected children have more than three episodes in the 12 months following diagnosis, with 16% developing bronchiectasis within two years.
Bronchiectasis is described as ‘an important cause of paediatric morbidity’ by researchers, particularly in disadvantaged communities with higher rates of acute respiratory infections.
They said they had not investigated how the presence of biofilm influenced longer term clinical outcomes, and the study did not consider the potential impact of comorbidities.

The low median age of the cohort (around two years old) was also highlighted, with the authors warning it might restrict the interpretation of the findings for older age groups.
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Dr Allan Michael Fasher   3/02/2022 9:54:27 PM

Thank you for this heads up. An article I will now look up and ponder. Puzzled by the data suggesting that persistent wet cough in children beyond 4 weeks is common. I have spent about 50 years attempting to help families deal with their concerns when their young children are coughing (and mostly in disadvantaged communities). Productive or wet cough lasting more than four weeks in preschoolers with healthy lungs is, in my experience, vanishingly small. I don't prescribe cough medicines (nor antibiotics for wet cough < 4 weeks for children with healthy lungs). Hmmm. Thanks again