Pneumonia in immunocompromised persons

Pneumonia in immunocompromised individuals is often caused by unusual pathogens. Symptoms depend on the microorganism. Diagnosis is based on bacteriological examination of blood and respiratory secretions taken during bronchoscopic examination. Treatment depends on the nature of the immunodeficiency and the pathogen.

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Causes pneumonia in immunocompromised persons

Pneumonia in immunocompromised patients can be caused by a variety of microorganisms. However, respiratory symptoms and chest X-ray changes in immunocompromised patients may develop not only due to infection but also as a result of other processes, such as pulmonary hemorrhage, pulmonary edema, radiation injury, pulmonary toxicity from cytotoxic drugs, and tumor infiltrates.

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Symptoms pneumonia in immunocompromised persons

Symptoms may be similar to those of community-acquired or hospital-acquired pneumonia in immunocompetent patients, although immunocompromised patients may not have fever or respiratory symptoms and are less likely to produce purulent sputum in the setting of neutropenia. In some patients, fever is the only symptom.

Diagnostics pneumonia in immunocompromised persons

Immunocompromised patients with respiratory symptoms, signs, or fever should have a chest radiograph. If an infiltrate is detected, diagnostic studies should include sputum Gram stain and blood culture. Optimally definitive diagnosis is made by examination of induced sputum and/or bronchoscopy, especially in patients with chronic pneumonia, atypical manifestations, severe immune deficiencies, and failure to respond to broad-spectrum antibiotics.

Likely pathogens can often be predicted based on symptoms, radiographic changes, and the type of immunodeficiency. Likely diagnoses in patients with acute symptoms include bacterial infection, hemorrhage, pulmonary edema, leukocyte agglutinin reaction, and pulmonary embolism. Subacute or chronic presentations are more suggestive of fungal or mycobacterial infection, opportunistic viral infection, Pneumocystis jiroveci (formerly P. carinii) pneumonia, tumor, cytotoxic drug reaction, or radiation injury.

Radiography showing localized consolidation usually indicates infection with bacteria, mycobacteria, fungi, or Nocardia. Diffuse interstitial changes are more likely to indicate viral infection, P. jiroveci pneumonia, drug or radiation injury, or pulmonary edema. Widespread nodular lesions suggest infection with mycobacteria, Nocardia, fungi, or tumor. Cavitary lesions are characteristic of mycobacteria, Nocardia, fungi, or bacteria.

In organ or bone marrow transplant recipients, bilateral interstitial pneumonia is often caused by cytomegalovirus, or the disease is considered idiopathic. Pleural consolidation is usually caused by aspergillosis. In patients with AIDS, bilateral pneumonia is usually caused by P. jiroveci infection. In approximately 30% of HIV-positive patients, P. jiroveci pneumonia is the first AIDS-defining diagnosis, and in more than 80% of AIDS patients, this infection occurs later if prophylaxis is not given. Patients with HIV infection become susceptible to P. jiroveci when the CD4+ helper cell count drops to <200/mm3.

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Treatment pneumonia in immunocompromised persons

In patients with neutropenia, empirical treatment of pneumonia in immunocompromised individuals depends on the immune defect, radiographic findings, and severity of illness. In general, broad-spectrum agents effective against gram-negative bacteria, Staphylococcus aureus, and anaerobes, as in hospital-acquired pneumonia, are needed.