Contributions to the knowledge of the aetiology of paediatric community-acquired pneumonia and the pathophysiology of persistent respiratory symptoms in preschool aged children

Community-acquired pneumonia (CAP) and persistent/recurrent respiratory symptoms are common problems in childhood. The current knowledge of the causative micro-organisms and underlying pathophysiology is limited, because aetiological diagnosis and studies are hampered by technical issues and ethical considerations. This work focuses on the aetiology of CAP and persistent/recurrent wheezing unresponsive to conventional asthma therapy, in children. In acute CAP, the predominance of Streptococcus pneumoniae as aetiological agent was confirmed and the predominant pneumococcal serotypes were determined. In addition, it was shown for the first time that in recurrent and unresponsive CAP, aetiology is different with predominance of non-typeable Haemophilus influenzae. In children with persistent/ recurrent wheezing, it was demonstrated that structural anomalies of the conductive airways, bronchial inflammation and bacterial infection are common. Moreover, it was shown for the first time that in case of bronchial infection, non-typeable Haemophilus influenzae is the bacteria most frequently involved. The obtained insights provide a basis for a better understanding of the epidemiology of childhood CAP and the underlying pathophysiology in persistent/recurrent wheezing