Clarifying the diagnosis of PBB
We congratulate Dr Pritchard and colleagues for reporting on a retrospective follow-up of their patient cohort with protracted bacterial bronchitis (PBB) and thank them for acknowledging the importance of PBB as a cause of chronic cough. The diagnostic criteria of PBB do however need clarification as the 10 children whose wet cough failed to resolve with antibiotics do not have PBB. Instead, they may have bronchiectasis, chronic suppurative lung disease or another cause of wet cough. Recently we showed (in a retrospective cohort of 144 children) that children whose wet cough did not improve after 4-weeks of antibiotics are significantly more likely to have radiolographically-proven bronchiectasis (adjusted odds ratio 5.86; 95%CI 1.20-28.5) [Arch Dis Child 2014; 99:522-5]. This observation supports published statements [Pediatr Pulmonol 2008;43:519- 31] that children whose wet cough does not respond to 4-weeks of antibiotics should undergo further investigation. Importantly, the clinical diagnosis of PBB is based upon three criteria (a) presence of a chronic (>4-weeks) wet cough; (b) resolution of the cough following 2- weeks of antibiotics; and (c) absence of other symptoms and signs suggestive of an alternative cause of wet cough [Med J Aust 2006;184:398- 403].
In Prichard and colleagues' study, 33 children did have PBB and some had recurrent episodes. Anecdotally, we find that ~50% of children with PBB have recurrent (>3) episodes, some of whom are found to have bronchiectasis. While prescribing prophylactic antibiotics is arguably justified in children with >3 episodes per year, we remain uncertain whether prophylactic antibiotics are warranted when these are less frequent and especially now with ongoing concerns over increasing antibiotic resistance. Clearly, a prospective longitudinal study is required to follow-up children with PBB to help inform clinical practice and is something we are pursuing currently.
Prof Anne B Chang and Prof Keith Grimwood
Conflict of Interest:
AC has potential intellectual competing interest as an author of many papers on PBB