An observational study in Protracted Bacterial Bronchitis, sponsored by University Hospital, Antwerp. Recruiting at 1 site in Belgium. Open to participants aged Up to 5 Years. Per ClinicalTrials.gov, last updated 2026-03-19.
Sponsored by University Hospital, Antwerp · Observational
This project aims to assess the relationship between the microbiome and virome composition, the immune responses, and the respiratory health of children with protracted bacterial bronchitis (PBB). In addition, we aim to evaluate how the standard treatment with azithromycin interacts with the components of the microbiome, virome and immune biomarkers.
Protracted Bacterial Bronchitis (PBB) is an often underestimated disease, characterized by a persistent cough for more than four weeks, without other significant underlying symptoms. While generally treatable, it can lead to complications such as recurrent infections and airway damage (bronchiectasis). The reasons why some children develop PBB or subsequent complications while others do not remain unclear. Recent research suggests that an impaired immune response and microbiota dysbiosis may play a key role. This study aims to analyze the microbial and viral composition of the airways in children with PBB, its relationship with inflammation, and the effects of azithromycin. Oropharyngeal swabs will be collected from up to 160 children \<5 years old diagnosed with PBB at UZA in a longitudinal setup during one year. At each routine consultation (five in total) and during an exacerbation episode, three oropharyngeal swabs will be collected from each child. The three swabs will be used to: (1) determine the microbiome composition using next-generation sequencing, (2) identify the virome composition using multiplex qPCR or similar approaches, and (3) quantify immune biomarkers (RNA and protein-level) and culture microbial isolates. These findings will help to better understand the role of the airway microbiome in young children with PBB and identify microorganisms that may have a pathogenic or protective role. Ultimately, this knowledge may contribute to the development of new and effective diagnostics and treatments for PBB from an early age.
427 studies on the registry are indexed under Cough; 67 are open to participants now.
This study's planned enrollment of 160 is above the median of 100 across 95 observational studies indexed under Cough.
Browse Cough studies →University Hospital, Antwerp is the lead sponsor of 242 studies on the registry; 66 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Children under five years old diagnosed with PBB.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Children under five years old who attend pediatric outpatient visits or well-child visits at University Hospital Antwerp (UZA) and are diagnosed with Protracted bacterial bronchitis.
Analysis of respiratory microbiome composition
Description: Analysis of microbiome communities in airway samples will be performed using amplicon or shotgun sequencing to determine relative microbial abundances (in percentages) as the unit of measure, coupled with the use of bioinformatic tools for community structure analysis.
Time frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Prevalence of respiratory viruses
Description: Detection of respiratory viruses from airway samples using RT-qPCR. Unit of Measure: percentage of positive samples (in percentages).
Time frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Immune biomarkers profiling in airway samples
Immunological profiling will be performed in airway samples by determining (1) cytokine concentrations based on protein-level analysis such as ELISA (pg/mL) and/or (2) differential gene expression based on RNA analysis (log fold-change or similar metric).
Time frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Correlates of respiratory microbiome
Description: Microbial profiles will be associated with demographic, epidemiological and clinical data collected through standardized questionnaires and clinical assessments to determine relevant correlates. Unit of Measure: Statistical association measure (e.g., correlation coefficients or similar).
Time frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Correlates of Protracted Bacterial Bronchitis
PBB events will be associated with demographic, epidemiological and clinical data collected through standardized questionnaires and clinical assessments to determine relevant correlates. Unit of Measure: Effect estimates (odds/prevalence/hazard ratios or similar).
Time frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Plan to share: Yes — The metadata of participants in the study will be made available in a restricted access repository. For samples and data sharing, the researchers will work with the legal department to establish Material/Data Transfer Agreements. Sequencing data are available at the European Nucleotide Archive. Physical samples are their origin will be stored at the decentral hub of the Antwerp biobank.
Time frame: After the completion of the study (intended in 2029) and before publication, sequences and related metadata will be deposited into the ENA database and made available indefinitely.
Access criteria: After data deposition in ENA, the data will be publicly accessible to anyone using the ENA instructions https://www.ebi.ac.uk/ena/browser/downloading-data
No publications or documents are linked to this record.
Started Jan 2026 (actual). Primary completion is estimated for Jan 2028, 24 months after the start.
Of 33 observational studies under Cough, half reached primary completion within 20 months of starting (the median), counting those still running; a quarter within 14. This study's planned 24 months is above that.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
University Hospital, Antwerp →