Etiopathogenesis of acute community acquired pneumonia

Abstract

Acute community pneumonia etiology is related to age and immune system status. Certain age groups (neonates, infants, ante-preschools, preschoolers, schoolchildren, adolescents, patients with severe immunosuppression) reveal particular aspects in immune defense mechanisms (macrophages, neutrophils, lymphocytes and eosinophils) and nonimmune responses (aerodynamic filtration of inhaled particle size, shape, electrostatic charge, cough reflex, mucociliary clearance, lysozyme, complement, defensine). Firstly, this review tackles the main mechanisms involved in airway permeability, alveolar ventilation and perfusion impairments, gas exchange and cellular metabolism alterations affecting vital tissues and organs. Then, the focus is on the age related pathogens interaction with the host defence systems, in different age groups.