Prevalence estimates of VAP are 6-52 cases per 100 pts, with the highest hazard ratio in the first 5 days of mechanical ventilation.

• Three factors important in the pathogenesis of VAP are colonization of the oropharynx with pathogenic microorganisms, aspiration of these organisms to the lower respiratory tract, and compromise of normal host defense mechanisms.
• Clinical manifestations are similar to those in other forms of pneumonia.