IS Case 9: Nocardia Pneumonia
Publication Date: 2009-05-18
Pulmonary infections are the the most common cause of infectious death after hematopoietic stem cell transplant (HSCT). Deficiencies in cellular and humoral immunity in HSCT recipients place these patients at high risk for bacterial and mycobacterial infections. Allogeneic transplantation is associated with a higher risk of infection than autologous transplantation, and matched, unrelated-donor transplants carry the greatest risk.
Nocardia pneumonia is not an uncommon infection in patients who have received HSCT. In a study comprised of 6759 HSCT recipients, 22 cases of proven or probable Nocardia infection were diagnosed a mean of 210 days after HSCT. Pulmonary involvement occurred in 56%, and eight patients had coinfection with other opportunistic pathogens. Nocardia are aerobic, gram positive organisms that live in the soil. They are acquired via inhalation, and less commonly by person to person transmission. Presenting symptoms of pulmonary infection include cough, chest pain, and fever, often with a protracted course. Nocardia infection may occur in immunocompetent persons, but most commonly occurs in those with underlying immunodeficiency, such as individuals on immunosuppressive therapy, chemotherapy, or with AIDS. Dissemination may occur in immunocompromised patients, often with spread to the brain. TMP-SMX is the recommended treatment for established nocardial infections.
Chest radiography or CT may demonstrate one or more areas of consolidation, or a solitary nodule or mass. Multiple nodules may be seen, especially in immunocompromised hosts. Decreased areas of attenuation may be seen, representing areas of necrosis. Pleural effusion or empyema is common, occurring in nearly 50% of cases. Chest wall invasion is uncommon.
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