title: Protracted bacterial bronchitis: The last decade and the road ahead.
abstract: Cough is the single most common reason for primary care physician visits and, when chronic, a frequent indication for specialist referrals. In children, a chronic cough (>4 weeks) is associated with increased morbidity and reduced quality of life. One common cause of childhood chronic cough is protracted bacterial bronchitis (PBB), especially in children aged <6 years. PBB is characterized by a chronic wet or productive cough without signs of an alternative cause and responds to 2 weeks of appropriate antibiotics, such as amoxicillin-clavulanate. Most children with PBB are unable to expectorate sputum. If bronchoscopy and bronchoalveolar lavage are performed, evidence of bronchitis and purulent endobronchial secretions are seen. Bronchoalveolar lavage specimens typically reveal marked neutrophil infiltration and culture large numbers of respiratory bacterial pathogens, especially Haemophilus influenzae. Although regarded as having a good prognosis, recurrences are common and if these are frequent or do not respond to antibiotic treatments of up to 4-weeks duration, the child should be investigated for other causes of chronic wet cough, such as bronchiectasis. The contribution of airway malacia and pathobiologic mechanisms of PBB remain uncertain and, other than reduced alveolar phagocytosis, evidence of systemic, or local immune deficiency is lacking. Instead, pulmonary defenses show activated innate immunity and increased gene expression of the interleukin-1β signalling pathway. Whether these changes in local inflammatory responses are cause or effect remains to be determined. It is likely that PBB and bronchiectasis are at the opposite ends of the same disease spectrum, so children with chronic wet cough require close monitoring.
authors.affiliation: Child Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia.|Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, Brisbane, Queensland, Australia.|Queensland Children's Medical Research Institute, Queensland University of Technology, Brisbane, Australia.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Chang
authors.affiliation: School of Medicine, University of Queensland, Brisbane, Australia.
authors.forename: John W
authors.initials: JW
authors.lastname: Upham
authors.affiliation: Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, Brisbane, Queensland, Australia.|Queensland Children's Medical Research Institute, Queensland University of Technology, Brisbane, Australia.
authors.forename: I Brent
authors.initials: IB
authors.lastname: Masters
authors.affiliation: University of Washington, Seattle, Washington.
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Redding
authors.affiliation: Priority Research Centre for Asthma and Respiratory Diseases, University of Newcastle, Callaghan, New South Wales, Australia.|Department of Respiratory and Sleep Medicine, Hunter Medical Research Institute, John Hunter Hospital, New Lambton Heights, New South Wales, Australia.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Gibson
authors.affiliation: Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, Brisbane, Queensland, Australia.|Queensland Children's Medical Research Institute, Queensland University of Technology, Brisbane, Australia.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Marchant
authors.affiliation: Queensland Children's Medical Research Institute, Children's Health Queensland, Brisbane, Queensland, Australia.|Menzies Health Institute Queensland, Griffith University and Gold Coast Health, Gold Coast, Queensland, Australia.
authors.forename: Keith
authors.initials: K
authors.lastname: Grimwood
mesh_terms: D000293:Adolescent; D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis*; D001987:Bronchiectasis / Q000150:complications / Q000175:diagnosis*; D001991:Bronchitis / Q000150:complications / Q000175:diagnosis*; D018893:Bronchoalveolar Lavage; D001999:Bronchoscopy; D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000209:etiology*; D006193:Haemophilus influenzae / Q000302:isolation & purification; D006801:Humans; D011788:Quality of Life; D012008:Recurrence
keywords: Haemophilus influenzae; airways; bacterial bronchitis; infection; inflammation; mechanism