Protracted Bacterial Bronchitis (PBB) in Children
Diagnostic criteria, red flags, and evidence-based management of chronic wet cough in paediatric general practice.
What is Protracted Bacterial Bronchitis?
Protracted Bacterial Bronchitis (PBB) is one of the leading causes of chronic, persistent wet (or "moist" / phlegmy) cough in young children, commonly under the age of 5. It occurs when a low-grade bacterial infection and associated biofilm establish in the major conducting airways, failing to clear spontaneously after a viral respiratory infection.
Children with PBB are frequently misdiagnosed as having asthma. However, unlike asthma—which typically presents with a dry night cough, wheeze, and responds to bronchodilators—PBB cough is characteristically wet, loose, and unresponsive to standard asthma inhalers (e.g. Ventolin).
Pathophysiology & Common Pathogens
The most common bacterial pathogens isolated in paediatric airway secretions of children with PBB are:
- Haemophilus influenzae (non-typeable)
- Streptococcus pneumoniae
- Moraxella catarrhalis
Because these organisms form biofilms within the respiratory mucosa, short 5-day courses of standard antibiotics frequently fail to eradicate the infection completely, leading to immediate recurrence of cough once the course finishes.
Clinical Management & Treatment Framework
In accordance with the Royal Children's Hospital Melbourne Paediatric Clinical Practice Guidelines and national respiratory frameworks:
- First-Line Antibiotic Therapy: Oral amoxicillin-clavulanate (augmentin) for an initial duration of 2 weeks. If the cough improves but has not fully resolved at 2 weeks, therapy is typically extended to 4 weeks.
- Alternative Agents: In children with proven penicillin hypersensitivity, macrolides (such as clarithromycin or azithromycin) or trimethoprim-sulfamethoxazole are considered based on clinical guidance.
- Cease Ineffective Asthma Medications: If asthma inhalers (SABA/ICS) were commenced purely for an isolated wet cough without true wheeze or atopic background, they should be reviewed and discontinued if showing no clinical benefit.
When to Refer to a Paediatrician or Pulmonologist
Further evaluation is warranted if:
- The wet cough persists despite 4 weeks of compliant antibiotic therapy.
- Recurrent episodes occur (e.g., >3 episodes of PBB in a 12-month period), which requires consideration of bronchiectasis or underlying structural/immune factors.
- There are signs of systemic illness, growth failure / poor weight gain, digital clubbing, or neonatally acquired cough.
- A history suggests possible foreign body inhalation (choking episode).