Lower airway microbiology and cellularity in children with newly diagnosed non-CF bronchiectasis.

BACKGROUND: Infection and inflammation are important in the pathogenesis of bronchiectasis. However, there are few published data describing the lower airway microbiology and cellularity in children.

METHODS: Children with non-cystic fibrosis (CF) bronchiectasis who underwent bronchoalveolar lavage (BAL) within 4 weeks of diagnosis were identified by a retrospective patient-record review. The effects of infection (≥10(5) colony-forming units of respiratory bacteria/ml; or detectable Pseudomonas aeruginosa; mycobacteria, fungi, mycoplasma, or respiratory viruses) on airway cellularity and the impact of age, gender, indigenous status, immune function, radiographic involvement and antibiotic usage on infection risk were evaluated.

RESULTS: Of 113 children [median age 63 months (IQR 32-95)] with newly diagnosed bronchiectasis, 77 (68%) had positive BAL cultures for respiratory bacterial pathogens. Haemophilus influenzae was most commonly detected, being present in 53 (47%) BAL specimens. P. aeruginosa was found in just 7 (6%) children, five of whom had an underlying disorder, while mycobacterial and fungal species were not detected. Respiratory viruses were identified in 14 (12%) children and Mycoplasma pneumoniae in two others. Overall, 56 (49.5%) children fulfilled our definition of a lower airway infection and of these, 35 (63%) had more than one pathogen present. Compared to children without infection, children with infection had higher total cell counts (610 vs. 280 × 10(6) /L), neutrophil counts (351 vs. 70 × 10(6) /L), and neutrophil percentages (69% vs. 34%). Age at diagnosis was most strongly associated with infection.

CONCLUSIONS: BAL microbiology of children with newly diagnosed bronchiectasis is dominated by H. influenzae. In the absence of CF, isolation of P. aeruginosa may suggest a serious co-morbidity in this group. Airway neutrophilia is common, especially with higher bacterial loads.