title: Prospective characterization of protracted bacterial bronchitis in children.
abstract: BACKGROUND
  Prior studies on protracted bacterial bronchitis (PBB) in children have been retrospective or based on small cohorts. As PBB shares common features with other pediatric conditions, further characterization is needed to improve diagnostic accuracy among clinicians. In this study, we aim to further delineate the clinical and laboratory features of PBB in a larger cohort, with a specific focus on concurrent viral detection.
  
  
  METHODS
  Children with and without PBB (control subjects) undergoing flexible bronchoscopy were prospectively recruited. Basic immune function testing and lymphocyte subset analyses were performed. BAL specimens were processed for cellularity and microbiology. Viruses were identified using polymerase chain reaction (PCR) and bacteria were identified via culture.
  
  
  RESULTS
  The median age of the 104 children (69% male) with PBB was 19 months (interquartile range [IQR], 12-30 mo). Compared with control subjects, children with PBB were more likely to have attended childcare (OR, 8.43; 95% CI, 2.34-30.46). High rates of wheeze were present in both groups, and tracheobronchomalacia was common. Children with PBB had significantly elevated percentages of neutrophils in the lower airways compared with control subjects, and adenovirus was more likely to be detected in BAL specimens in those with PBB (OR, 6.69; 95% CI, 1.50-29.80). Median CD56 and CD16 natural killer (NK) cell levels in blood were elevated for age in children with PBB (0.7 × 109/L; IQR, 0.5-0.9 cells/L).
  
  
  CONCLUSIONS
  Children with PBB are, typically, very young boys with prolonged wet cough and parent-reported wheeze who have attended childcare. Coupled with elevated NK-cell levels, the association between adenovirus and PBB suggests a likely role of viruses in PBB pathogenesis.
authors.affiliation: Queensland Children's Medical Research Institute, The University of Queensland, and Queensland Children's Respiratory Centre, Royal Children's Hospital, Brisbane, QLD. Electronic address: Danielle.wurzel@uqconnect.edu.au.
authors.forename: Danielle F
authors.initials: DF
authors.lastname: Wurzel
authors.affiliation: Queensland Children's Medical Research Institute, The University of Queensland, and Queensland Children's Respiratory Centre, Royal Children's Hospital, Brisbane, QLD.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Marchant
authors.affiliation: School of Medicine, The University of Queensland, Brisbane, QLD; Queensland Lung Transplant Service, The Prince Charles Hospital, Brisbane, QLD.
authors.forename: Stephanie T
authors.initials: ST
authors.lastname: Yerkovich
authors.affiliation: School of Medicine, The University of Queensland, Brisbane, QLD; Department of Respiratory Medicine, Princess Alexandra Hospital, Brisbane, QLD.
authors.forename: John W
authors.initials: JW
authors.lastname: Upham
authors.affiliation: Queensland Paediatric, Infectious Diseases Laboratory, Queensland Children's Medical Research Institute, Sir Albert, Sakzewski Virus Research Centre, Children's Health Queensland Hospital and Health Service, The University of Queensland, Herston, QLD.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Mackay
authors.affiliation: Queensland Children's Medical Research Institute, The University of Queensland, and Queensland Children's Respiratory Centre, Royal Children's Hospital, Brisbane, QLD.
authors.forename: I Brent
authors.initials: IB
authors.lastname: Masters
authors.affiliation: Queensland Children's Medical Research Institute, The University of Queensland, and Queensland Children's Respiratory Centre, Royal Children's Hospital, Brisbane, QLD; Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Chang
mesh_terms: D000256:Adenoviridae / Q000302:isolation & purification; D000257:Adenoviridae Infections / Q000175:diagnosis / Q000453:epidemiology; D001424:Bacterial Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology*; D001991:Bronchitis / Q000175:diagnosis* / Q000382:microbiology* / Q000473:pathology; D001992:Bronchoalveolar Lavage Fluid / Q000821:virology; D016022:Case-Control Studies; D002452:Cell Count; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity; D003371:Cough / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D007107:Immune System / Q000503:physiopathology*; D007223:Infant; D007694:Killer Cells, Natural / Q000473:pathology; D016131:Lymphocyte Subsets / Q000473:pathology*; D008297:Male; D009504:Neutrophils / Q000473:pathology; D011446:Prospective Studies; D012737:Sex Factors