Pathophysiology of pneumonia

Abstract

The development of pneumonia requires that a pathogen reach the alveoli and that the host defenses are overwhelmed by microorganism virulence or by the inoculum size. The endogenous sources of microorganisms are nasal carriers, sinusitis, oropharynx, gastric, or tracheal colonization, and hematogenous spread. Other external sources of contamination, such as intensive care unit workers, aerosols, or fibrobronchoscopy, must be considered as accidental.