Protracted bacterial bronchitis: What it is, what it isn't

PBB is clinically defined as (a) the presence of isolated chronic (>4 weeks) wet/productive cough, (b) resolution of cough with antibiotic treatment and (c) absence of pointers suggestive of an alternative specific cause of cough. While the original description¹ included a criteria that required findings from bronchoalveolar lavage (BAL), it was later adapted for clinical use in the same year as undertaking BAL routinely in a child with chronic wet or productive cough is unwarranted and not feasible. While initially not well accepted, it is now incorporated in most international chronic cough guidelines,² has its own ICD-11 code, and an European Respiratory Society (ERS) taskforce document.³ Currently, suggestions for classifying PBB are PBB-clinical, PBB-micro, PBB-extended and recurrent PBB.⁴

 

The clinical descriptions of children with PBB are now well known i.e. they are typically very young (median age ~2 years) and may have parent-reported wheeze. Their chest x-rays of children with PBB may be reported as ‘normal’ but usually show peribronchiolar changes. Co-existent trachea-bronchomalacia⁵ may be present and in the 5 year follow-up study, some children are later found to have concurrent asthma.⁶

 

In PBB, the child’s cough resolves only after a prolonged course (usually 2 weeks) of appropriate antibiotics⁷ with resultant improved cough-specific and generic health related quality of life measures.⁴ Some children require 4 weeks of antibiotics. A placebo-controlled RCT found that a 4-week course of amoxicillin-clavulanate for treating children with chronic wet cough and suspected PBB conferred little advantage compared with a 2-week course in achieving clinical cure by 28 days. However, as a 4-week duration led to a longer cough-free period, identifying children who would benefit from a longer antibiotic course is a priority.⁸ 

 

Some children with PBB have recurrent episodes (>3/year) and some progress to bronchiectasis.⁹ Thus, children with PBB should be clinically reviewed. Predictors of disease progression are recurrence (>3/year) and presence of non-typeable H. influenzae in the BAL.⁹ These findings were consolidated in the 5 year follow-up of 166 children with PBB.⁶ 

 

Readers are referred to recent publications for reasons outlining how and why PBB is closely linked with bronchiectasis as a continuum. ^4,10 This was first proposed a decade ago¹¹ and recent studies support this.^4,12 Adult-based studies on PBB are emerging¹³ but not yet widely accepted.

 

The microbiome of children with PBB are increasing known.¹⁴ However, there are still much to be leant on the pathophysiology and pathobiology. In the lecture, current data on PBB and key differentiating features of PBB from other causes of chronic cough will be presented. 

 

References

1 Marchant JM, Masters IB, Taylor SM, Cox NC, Seymour GJ, Chang AB. Evaluation and outcome of young children with chronic cough. Chest 2006; 129: 1132-41.

2 Chang AB, Oppenheimer JJ, Irwin RS. Managing Chronic Cough as a Symptom in Children and Management Algorithms: CHEST Guideline and Expert Panel Report. Chest 2020; 158: 303-29.

3 Kantar A, Chang AB, Shields MD, et al. ERS statement on protracted bacterial bronchitis in children. Eur Respir J 2017; 50: 1602139.

4 Chang AB, Upham JW, Masters IB, et al. State of the art. Protracted bacterial bronchitis: the last decade and the road ahead. Pediatr Pulmonol 2016; 51: 225-42.

5 Kompare M, Weinberger M. Protracted Bacterial Bronchitis in Young Children: Association with Airway Malacia. J Pediatr 2012; 160: 88-92.

6 Ruffles TJC, Marchant JM, Masters IB, et al. Outcomes of protracted bacterial bronchitis in children: A 5-year prospective cohort study. Respirology 2021; 26: 241-48.

7 Marchant JM, Masters IB, Champion A, Petsky HL, Chang AB. Randomised controlled trial of amoxycillin-clavulanate in children with chronic wet cough. Thorax 2012; 67: 689-93.

8 Ruffles TJC, Goyal V, Marchant JM, et al. Duration of amoxicillin-clavulanate for protracted bacterial bronchitis in children (DACS): a multi-centre, double blind, randomised controlled trial. Lancet Respir Med 2021; 9: 1121-29.

9 Wurzel DF, Marchant JM, Yerkovich ST, et al. Protracted bacterial bronchitis in children: Natural history and risk factors for bronchiectasis. Chest 2016; 150: 1101-08.

10 Chalmers JD, Chang AB, Chotirmall SH, Dhar R, McShane PJ. Bronchiectasis. Nature Rev Dis Primers 2018; 4: 45.

11 Chang AB, Redding GJ, Everard ML. State of the Art - Chronic wet cough: protracted bronchitis, chronic suppurative lung disease and bronchiectasis. Pediatr Pulmonol 2008; 43: 519-31.

12 Chang AB, Bush A, Grimwood K. Bronchiectasis in children: Diagnosis and Treatment. Lancet 2018; 392: 866-79.

13 Martin MJ, Lee H, Clayton C, et al. Idiopathic chronic productive cough and response to open-label macrolide therapy: An observational study. Respirology 2019; 24: 558-65.

14 Atto B, Anteneh Y, Bialasiewicz S, et al. The Respiratory Microbiome in Paediatric Chronic Wet Cough: What Is Known and Future Directions. J Clin Med 2023; 13: 171.