BACTERIAL PNEUMONIA IN IMMUNOCOMPROMISED PATIENTS

Immunocompromised patients develop infections resulting from a wide ra nge of organisms. The most commonly encountered type of infection is b acterial in origin. Many of the infections are community-acquired pneu monias in which most of the infections are caused by organisms that ty pically produce disease in the healthy person. Hospital-acquired pneum onias are particularly serious, being caused by the highly virulent gr am-negative bacilli and Staphylococcus aureus. Immunocompromised patie nts frequently have indwelling intravascular catheters. These catheter s may become infected and seed the lung with septic emboli, producing a hematogenous pneumonia. Underlying conditions and therapy increase t he risk for aspiration in the immunocompromised patient. These aspirat ions can result in the development of an aspiration pneumonia and lung abscess formation. The majority of pneumonias resulting from Legionel la and Nocardia occur in immunocompromised patients.