What is the diagnosis and treatment for protracted bacterial bronchitis (PBB)?

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Last updated: April 21, 2025View editorial policy

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From the Guidelines

Protracted bacterial bronchitis (PBB) should be treated with a 2-week course of antibiotics, with amoxicillin-clavulanate being the recommended first-line treatment at a dose of 45 mg/kg/day (based on amoxicillin component) divided twice daily. This recommendation is based on the findings of a systematic review and expert panel report published in the journal Chest in 2017 1. The review found that a 2-week course of antibiotics is sufficient for most children with PBB, but a longer course of up to 4 weeks may be required in some cases. The use of amoxicillin-clavulanate as the first-line treatment is supported by its effectiveness against common respiratory bacteria such as Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis.

Key Points

  • PBB is a chronic wet cough condition lasting more than 4 weeks that responds to antibiotic treatment
  • The recommended first-line treatment is amoxicillin-clavulanate at a dose of 45 mg/kg/day (based on amoxicillin component) divided twice daily for 2 weeks
  • Alternative antibiotics for penicillin-allergic patients include azithromycin or clarithromycin
  • PBB primarily affects young children and is characterized by persistent cough with mucus production, absence of other specific causes, and neutrophilic airway inflammation
  • The condition is caused by bacterial infection forming biofilms in the airways, and without proper treatment, PBB can lead to bronchiectasis

Diagnosis and Treatment

The diagnosis of PBB requires excluding other causes of chronic cough such as asthma, foreign body aspiration, or cystic fibrosis. A systematic review and expert panel report published in the journal Chest in 2017 1 provides guidance on the management of children with chronic wet or productive cough unrelated to established chronic lung disease. The report recommends that children with chronic wet or productive cough receive 2 weeks of antibiotics targeted to common respiratory bacteria and local antibiotic sensitivities. If the cough resolves within 2 weeks of treatment, the diagnosis of PBB can be made. If the cough persists after 2 weeks of treatment, an additional 2 weeks of antibiotics may be necessary. Further investigations such as flexible bronchoscopy and/or chest computed tomography may be required if the cough persists after 4 weeks of treatment.

From the Research

Definition and Characteristics of Protracted Bacterial Bronchitis

  • Protracted bacterial bronchitis (PBB) is a leading cause of chronic wet cough in children, characterized by a chronic wet or productive cough without signs of an alternative cause and responds to 2 weeks of appropriate antibiotics, such as amoxicillin-clavulanate 2.
  • In adults, PBB is characterized by productive cough, yellow phlegm, sensation of mucus in the throat (SMIT), and neutrophilic airway inflammation 3.

Treatment and Duration of Antibiotic Course

  • The current standard treatment for PBB is 2 weeks of antibiotics, but the optimal duration of therapy is unknown 4.
  • A study found that a 4-week course of amoxicillin-clavulanate confers little advantage compared with a 2-week course in achieving clinical cure by 28 days, but led to a longer cough-free period 4.
  • Another study found that the duration of initial antibiotic treatment was significantly associated with recurrent PBB, with those who received antibiotics for 6 weeks being less likely to develop recurrent PBB than those who received for 2 weeks 5.

Clinical Outcomes and Recurrence

  • Recurrence of PBB is common, and recurrent PBB (>3 episodes in 12 months) is associated with a future diagnosis of bronchiectasis 5, 2.
  • A study found that the rate of recurrence of PBB at 6 months was 53% in the 4-week group and 74% in the 2-week group, but the difference between the groups was not significant 4.

Diagnostic Value of Clinical Features

  • Clinical features such as productive cough, yellow phlegm, SMIT, and increased sputum lymphocytes may be useful to indicate PBB in adults 3.
  • A study found that these cough features and increased sputum lymphocytes had moderate sensitivity and moderate-high specificity for determining PBB 3.

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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