['The role of human adenoviruses (HAdVs) in chronic respiratory disease pathogenesis is recognized. However, no studies have performed molecular sequencing of HAdVs from the lower airways of children with chronic endobronchial suppuration. We thus examined the major HAdV genotypes/species, and relationships to bacterial coinfection, in children with protracted bacterial bronchitis (PBB) and mild bronchiectasis (BE).', 'Bronchoalveolar lavage (BAL) samples of 245 children with PBB or mild (cylindrical) BE were included in this prospective cohort study. HAdVs were genotyped (when possible) in those whose BAL had HAdV detected (HAdV(+)). Presence of bacterial infection (defined as ≥10(4) colony-forming units/mL) was compared between BAL HAdV(+) and HAdV negative (HAdV(-)) groups. Immune function tests were performed including blood lymphocyte subsets in a random subgroup.', 'Species C HAdVs were identified in 23 of 24 (96%) HAdV(+) children; 13 (57%) were HAdV-1 and 10 (43%) were HAdV-2. An HAdV(+) BAL was significantly associated with bacterial coinfection with Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae (odds ratio [OR], 3.27; 95% confidence interval, 1.38-7.75; P = .007) and negatively associated with Staphylococcus aureus infection (P = .03). Young age was related to increased rates of HAdV(+). Blood CD16 and CD56 natural killer cells were significantly more likely to be elevated in those with HAdV (80%) compared with those without (56.1%) (P = .027).'] Is adenovirus species C associated with chronic suppurative lung diseases in children?