Life-threatening pneumonia.

Severe pneumonia can be acquired by previously healthy patients, those with pre-existing illness, or those hospitalized for an unrelated illness. Because diagnosis is frequently difficult or delayed, treatment is usually empirically tailored to the most probable offending organisms and the patient's condition. This article reviews the pathogenesis of community- and hospital-acquired pneumonia, clinical features, and diagnostic techniques. An approach to selecting an antibiotic regimen is suggested.