Airway Microbiome of Patients With Protracted Bacterial Bronchitis

March 18, 2026 updated by: University Hospital, Antwerp

Interaction Between Microbiome, Virome and Host Immunity Response in the Context of Protracted Bacterial Bronchitis

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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

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.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
160

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Belgium
      • Edegem, Belgium, 2650
        • Recruiting
        • Antwerp University Hospital
        • Contact:
        • Principal Investigator:
          • Kim Van Hoorenbeeck, Prof. dr.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

Children under five years old diagnosed with PBB.

Description

Inclusion Criteria:

  • Children with PBB diagnosis according to case definition
  • Consent form signed by parents or legal guardians

Exclusion Criteria:

  • Comorbidities (HIV, asthma, chronic obstructive pulmonary disease, diabetes)
  • Have had serious illnesses (meningitis, pneumonia, bacteremia, empyema, etc) in the previous three months, identified only at the time of enrollment.
  • Have chronic respiratory conditions at the time of enrollment (non-PBB bronchiectasis not caused by PBB, CF, allergy, etc.).
  • Having received mechanical ventilation.
  • Having been hospitalized or used antibiotics in the previous three months at the time of enrollment.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Participants with Protracted bacterial bronchitis diagnostic
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.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Analysis of respiratory microbiome composition
Time Frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
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.
Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Prevalence of respiratory viruses
Time Frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Description: Detection of respiratory viruses from airway samples using RT-qPCR. Unit of Measure: percentage of positive samples (in percentages).
Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Immune biomarkers profiling in airway samples
Time Frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
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).
Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Correlates of respiratory microbiome
Time Frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
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).
Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
Correlates of Protracted Bacterial Bronchitis
Time Frame: Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations
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).
Baseline, 3 months, 6 months, 9 months, 12 months and during exacerbations

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University Hospital, Antwerp

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Kim Van Hoorenbeeck, Prof. dr., University Hospital, Antwerp
  • Principal Investigator: Irina Spacova, Prof. dr. ir., Universiteit Antwerpen

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 7, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 1, 2029

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 1, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 19, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 1, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 19, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 18, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • BUN B3002025000069

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

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.

IPD Sharing 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.

IPD Sharing 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

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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