Pneumonia in immunocompromised patients

[Tracie Lynn]

Pneumonia in immunocompromised patients is often caused by unusual pathogens but may also be caused by the same pathogens as those that cause community-acquired pneumonia. Symptoms and signs depend on the pathogen and on the conditions compromising the immune system. Diagnosis is based on blood cultures and bronchoscopic sampling of respiratory secretions, sometimes with quantitative cultures. Treatment depends on the immune system defect and the pathogen.
(See also Overview of Pneumonia.)
The potential pathogens in patients with compromised immune system defenses are legion; they include those that cause community-acquired pneumonia as well as unusual pathogens. Likely pathogens depend on the type of defect in immune system defenses (see table Pneumonia in Immunocompromised Patients). However, respiratory symptoms and changes on chest x-rays in immunocompromised patients may be due to various processes other than infection, such as pulmonary hemorrhage, pulmonary edema, radiation injury, pulmonary toxicity due to cytotoxic drugs, and tumor infiltrates.