Recurrent, protracted and persistent lower respiratory tract infection: A neglected clinical entity

Community-acquired pneumonia is a potentially life-threatening disease affecting children worldwide. Recurrent pneumonia episodes can lead to the development of chronic respiratory morbidity. Chronic wet cough, a common pediatric complaint, is defined as a wet cough indicating excessive airway mucus that lasts for a minimum of 4 weeks. Most children with a chronic wet cough do not suffer from underlying debilitating pulmonary disorders. Rather, chronic wet cough is generally associated with neutrophilic airway inflammation and bacterial infections of the conducting airways. Failure to characterize endobronchial infections has led to under-recognition of chronic wet cough as an important clinical entity in children. Under-recognition and under-treatment of protracted bacterial bronchitis (PBB), a diagnosis made by the presence of isolated cough >4 weeks that resolves with appropriate antibiotic treatment, may lead to the development of chronic suppurative lung disease (CSLD) and bronchiectasis. The burden of bronchiectasis is highest in developing countries and in specifically vulnerable populations in developed countries, in particular indigenous children living in remote communities. The incidence, hospitalization rates and risk of long term sequelae of childhood pneumonia in indigenous children are higher than in non-indigenous children residing in the same area. The overlapping clinical and pathophysiological characteristics of PBB, CSLD and bronchiectasis are the presence of a chronic wet cough, impaired mucociliary clearance of the conducting airways, the presence of endobronchial bacterial infection (mainly non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis) and neutrophilic airway inflammation. The principles of managing PBB, CSLD and bronchiectasis are the same. More research and public health interventions are required to improve the awareness, diagnosis and management of these causes of chronic wet cough in children.