Recognising and managing protracted bacterial bronchitis in children

Under the radar: In the next in our series, Dr James Chambers describes the under-recognised condition protracted bacterial bronchitis, which might be overlooked in a child with an ongoing cough 

Note details of the case in this article have been changed to ensure anonymity

The case

In the middle of winter, a 4-year-old boy was seen in clinic for an ongoing cough. Initially as the cough had persisted only for a few days and the child was systemically well, it was diagnosed as a common viral upper respiratory infection.

However, by 4 weeks when the child was seen again by the same clinician, the cough was still present. This time, the cough was more noticeably productive and the patient’s mother mentioned that he had ‘rattly breathing’ – unusual for a viral infection.

The child was examined thoroughly and found to be well with no positive signs on chest auscultation and no fever or tachycardia to suggest a bacterial lower respiratory infection.

He had no history of aspiration or recurrent infections, no family history of chronic lung disease and no personal history of wheeze or atopy. His growth was normal, making bronchiectasis unlikely.

The outcome

Given the unusual presentation, a diagnosis of protracted bacterial bronchitis (PBB) was considered.  The child was treated with a 2-week course of co-amoxiclav in line with Cochrane review evidence supporting antibiotic treatment of chronic wet cough lasting more than 4 weeks in children, and on follow up, the symptoms had resolved.

What is PBB?

This is a condition many clinicians may not have heard of before. NICE makes no reference to it in any of its guidelines, and it was only first mentioned in a study in Australia in 2006. Despite this it has now gained worldwide recognition and a definition is included in European Respiratory Society (ERS) guidance as follows;

• The presence of a chronic (>4 week duration) wet or productive cough in a child.
• Absence of symptoms or signs suggestive of other causes of wet or productive cough (see box 1 below).
• Cough resolution after a 2-4 week course of an appropriate antibiotic.

Pathophysiology in PBB

The exact cause of PBB remains unclear although multiple mechanisms have been suggested. Predominantly the bacteria Haemophilus influenzae has been found in high bacterial loads of PBB patients relative to control groups, which is thought to contribute to high levels of neutrophilic inflammation and chronic changes in the airway.

The role of a ‘biofilm’ in these patients (a thick matrix which encloses bacterial growth within it) is thought to be important, which decreases the ability for antibiotics to penetrate the bacteria and hence both drives this chronic inflammation and persistent cough, and influences the way the condition is managed.

Management of PBB

Children with PBB should be treated with antibiotics for at least 2 weeks, in order to ensure that the biofilm is effectively penetrated. A sputum culture may help to guide antibiotic choice, although practically, there are challenges in obtaining a spontaneous sputum culture in these young children. The empirical antibiotic of choice for treatment is co-amoxiclav (as it is active against B-lactamase producing strains of H. influenzae) although a macrolide or a 2nd/3rd generation cephalosporin are also mentioned in ERS guidelines.

Research has shown that courses of antibiotics may need to be extended up to 4 weeks of treatment, although poor response beyond this was associated with an increased likelihood of underlying bronchiectasis. Indeed, there does seem to be some overlap between the mechanisms of both conditions, and there is some suggestion that recurrent episodes of PBB can result in bronchiectasis developing.

If the cough persists despite a four-week treatment course, urgent referral to paediatrics is warranted to investigate for possible bronchiectasis or other underlying respiratory diseases. In some children with ongoing symptoms, even more prolonged causes or prophylactic antibiotics (essentially in winter) may be warranted under specialist care.

Learning points for GPs

• In a child with a prolonged wet cough for more than 4 weeks who is otherwise well with no other signs of respiratory illness as discussed above, consider PBB.
• PBB can often be mistaken for other more common causes of chronic cough such as asthma, showing the importance of clear history taking, identifying risk factors for conditions and reconsidering the diagnosis if they do not respond to the usual treatment.
• Initially causes of chronic cough such as PBB may be misdiagnosed as common causes of acute cough during the early stages, such as a viral illness. Continuity of care to recognise when things are amiss and clear safety netting/follow-up plans are essential in not missing these diagnoses.
• Consider 2-4 weeks of prolonged antibiotics in patients presenting with PBB, but recognise when to refer on to paediatrics and the potential overlap with other conditions such as bronchiectasis.

Dr James Chambers is a GP in Staffordshire

Sources and further reading

• Kantar A, Chang A, Shields M et al. ERS statement on protracted bacterial bronchitis in children. Eur Respir J 2017 Aug 24;50(2):1602139
• Gallucci M, Pedretti M, Giannetti A et al. When the cough does not improve: A review on protracted bacterial bronchitis in children. Front Pediatr 2020;8:433    
• Marchant J, Masters I, Taylor S et al. Evaluation and outcome of young children with chronic cough. Chest 2006;129:1132–41
• Marchant J, Petsky H, Morris P et al. Antibiotics for prolonged wet cough in children. Cochrane Database Syst Rev 2018;7(7): CD004822