Etiology and pathophysiology

Community-acquired pneumonia (CAP) is the most common cause of death due to infection in industrial nations and the most common cause of death in low-income countries. Although it can cause disease at any age, it primarily affects the young (≤5 years of age) and elderly (≥65 years of age). CAP is primarily caused by bacteria, but can be due to a wide range of microbial pathogens. This chapter will focus on the pathophysiology of CAP and its etiology in both adults, children and neonates.