Protracted Bacterial Bronchitis

Protracted bacterial bronchitis is a chronic wet cough lasting more than 4 weeks in a child who is otherwise well, which resolves with 2 weeks of an appropriate antibiotic and has no features of another specific cause. It is a common cause of chronic wet cough in preschool children.

It is most frequent between 6 months and 6 years of age, and recurrent episodes are defined as 3 or more in 12 months. If episodes persist and structural change develops, chronic suppurative lung disease and bronchiectasis may follow.

Organisms are mostly non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis. Risk factors are childcare attendance, tobacco smoke exposure, malacia of the airways, and immune or ciliary defects.

Pathophysiology.

Impaired mucociliary clearance and airway inflammation, often after a viral infection, allow persistent bacterial infection of the lower airway, with biofilm formation and neutrophilic inflammation.

Airway malacia and prior infections reduce clearance and predispose to recurrence.

• Chronic wet or productive cough, often worse at night and on waking, with no clinical signs of other disease.
• Possible rattling chest or transmitted noises, and wheeze that does not respond to bronchodilators.
• Child is well, with normal growth and no digital clubbing.

Red flags.

• Cough from birth or after choking, failure to thrive, clubbing, chest deformity or abnormal chest signs.
• Recurrent pneumonia, haemoptysis, unusual infections, or a history of chronic suppurative ear disease.
• Failure to respond to a 4-week antibiotic course, or more than 3 episodes in a year.

• Clinical diagnosis: wet cough for more than 4 weeks, resolving with antibiotics in 2 weeks, no features of a specific cough.
• Chest X-ray (normal or mild peribronchial changes), spirometry in older children, and sputum or cough swab culture when available.
• Where there are recurrent episodes or red flags: sweat chloride, immunoglobulins and vaccine antibody titres, tests for ciliary dysfunction (nasal nitric oxide, ciliary biopsy), HIV, bronchoscopy with bronchoalveolar lavage, and high resolution CT for bronchiectasis.
• Test for tuberculosis where endemic.

Differential diagnosis. Asthma, post-infectious cough, cystic fibrosis, primary ciliary dyskinesia, bronchiectasis, immune deficiency, foreign body, tuberculosis, airway malacia, aspiration and gastro oesophageal reflux.

• Amoxicillin-clavulanate 22.5 mg/kg (of the amoxicillin component) orally every 12 hours for 2 weeks (up to 4 weeks if the cough remains or the child is slow to respond), to a maximum of 875 mg amoxicillin for each dose.
• Penicillin allergy: cefuroxime 15 mg/kg orally every 12 hours (maximum 500 mg) for 2 to 4 weeks, or a macrolide such as azithromycin 10 mg/kg once daily (maximum 500 mg) for 3 days, depending on local resistance patterns.
• Reduce smoke exposure and treat contributory conditions, such as malacia and reflux.
• Review at the end of the course. If the cough returns after stopping, give a second course and investigate for an underlying disorder.
• For recurrent protracted bacterial bronchitis (3 or more episodes in a year), investigate fully and consider longer courses (4 to 6 weeks), airway clearance physiotherapy, and prophylactic azithromycin 5 to 10 mg/kg 3 times weekly for selected children under specialist direction.

Monitoring. Resolution of cough, growth, recurrence and development of chronic suppurative lung disease. Repeat review at 4 weeks and 3 months.

Referral and escalation. Refer to paediatric respiratory services for recurrent episodes, persistent cough despite 4 weeks of antibiotics, clubbing, abnormal imaging or suspected immune deficiency.