Protracted Bacterial Bronchitis in Adults and comparison to Bronchiectasis

<title>Extract</title> Protracted bacterial bronchitis (PBB) is a well-described clinical entity in children, where it is a common cause of wet cough [1], but it is less well understood in adults, in whom there has been no published prospective characterisation. In children, various definitions have been developed, with some based on purely clinical criteria and others mandating microbiological culture of respiratory pathogens [2]. An ERS position statement in 2017 defined paediatric PBB as requiring all of<italic>:</italic> 1) Presence of a continuous chronic (>4 weeks’ duration) wet or productive cough; 2) absence of symptoms or signs suggestive of other causes of wet or productive cough and 3) resolution of cough following a 2–4-week course of an appropriate oral antibiotic [3]. Typical respiratory pathogens (including <italic>Haemophilus influenzae</italic>, <italic>Streptococcus pneumoniae</italic>, <italic>Klebsiella pneumoniae and Moraxella catarrhalis)</italic> are commonly isolated [4, 5]. The role of dysbiosis in PBB development is still uncertain, but in a paediatric setting, a dysregulated microbiota, with reduced bacterial diversity and an expansion of <italic>Haemophilus</italic> and <italic>Neisseria</italic>, has been found [6].