Protracted bacterial bronchitis and links with bronchiectasis-PRO/CON Debate 1.1. PBB-a precursor to bronchiectasis? (Pro)

Abstract

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. PBB has been officially recognized in chronic cough guidelines of many countries and a European Respiratory Society (ERS) taskforce document has also been produced.2 Currently, suggestions for classifying PBB are PBBclinical, PBB-micro, PBB-extended and recurrent PBB.3 Children with PBB are typically very young (median age ∼2 years) and may have parent-reported wheeze. The reported 'wheeze' may actually be a rattle (reflective of airway secretions) and not a true wheeze.4 However, children with PBB may have co-existent asthma, although in a prospective cohort study, median peripheral blood eosinophils, total IgE and RAST testing for common aeroallergens in children with PBB were similar to controls.5 The chest X-rays of children with PBB may be reported as 'normal' but usually show peribronchiolar changes. In many children, co-existent trachea-bronchomalacia6 is present although we found no significant difference in the frequency of trachea-bronchomalacia between children with PBB and 'non-PBB controls' (children with respiratory symptoms but did not have PBB).5 Common respiratory pathogens found in the bronchoalveolar lavage (BAL) of children with PBB are H. influenza (mostly nontypeable), S. pneumoniae and M. catarrhalis. In the original description of PBB,1 children who had the classical respiratory viruses detected by PCR were excluded, so as to obtain a 'clean group'. 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.3 Some children required up to 4 weeks of antibiotics. Anecdotal experience suggests that when shorter courses of antibiotics are used, the cough subsides but does not resolve and/or resolves but recurs very quickly. Reasons for this are unknown but one postulate is that longer courses of antibiotics are required to overcome the bacteria associated with formation of biofilms, demonstrated in the BAL of children without cystic fibrosis or Pseudomonas aeruginosa infection.3 Some children with PBB have recurrent episodes ( > 3/y) and some progress to bronchiectasis.8 Thus, children with PBB should be clinically reviewed. Predictors of disease progression are recurrence ( > 3/y) and presence of non-typeable H. influenzae in the BAL.8 Further, while chronic wet/productive cough in children often signify PBB, wet cough could also be the marker of other conditions. Readers are referred to recent publications for reasons outlining how and why PBB is closely linked with bronchiectasis as a continuum.3,9 This was first proposed a decade ago4 and recent studies support this, as recently summarized.3,10 The clear reason why the motion for the strong link between PBB and bronchiectasis should be supported is that Prof. Bush has coauthored a review regarding the paradigm of the spectrum linking PBB with bronchiectasis as a continuum with chronic endobronchitis being the common thread.10 This paradigm is based on decades-old and more recent studies using new technology. It is framed around the notion that primary prevention of bronchiectasis is possible and the knowledge that early detection of causal conditions (eg hypogammaglobulinemia) substantially reduces the risk of the future development of bronchiectasis through early initiation of treatment and optimal care. In children, mild (ie when detected early) bronchiectasis is potentially reversible. 9,10 Many factors influence progression of the illness, most of which are modifiable and represent potential inter ention points. These factors (secondary prevention) include better clinical management and guideline implementation. The paradigm emphasizes that prompt diagnosis and optimal management of bronchiectasis is particularly important in childhood with opportunities for its reversal of bronchiectasis and/or halting disease progression.9,10.L6287105342019-08-05 <br />