Pulmonary and disseminated nocardiosis are clearly associated with immunocompromising conditions, with approximately 60% of cases of nocardiosis other than mycetoma occurring in individuals with some compromise of host defense systems. Conditions associated with an increased risk of pulmonary and disseminated nocardiosis include the following:
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Chronic pulmonary disease: Although pulmonary nocardiosis has been described in association with various chronic pulmonary diseases, patients with pulmonary alveolar proteinosis are at particular risk.
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Alcoholism
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Lymphoreticular malignancy
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Solid-organ transplantation [22]
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Bone marrow or stem cell transplantation, particularly allogeneic transplantation with subsequent graft versus host disease
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Long-term corticosteroid use or Cushing syndrome
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Systemic lupus erythematosus
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Systemic vasculitis
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Sarcoidosis
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Renal failure
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Treatment with anti–tumor necrosis factor antibody
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HIV infection and AIDS: Nocardiosis in individuals with advanced HIV disease usually presents as a relentlessly progressive infiltrative pulmonary infection. The median CD4 count in patients infected with HIV who develop nocardiosis is approximately 50 cells/µL. [15]
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High-power microscopic appearance of Nocardia. Image courtesy of CDC.
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Photomicrograph of tissue biopsy stained with Gomori methenamine silver demonstrating acute inflammatory response and organisms compatible with Nocardia.
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Plain chest radiograph in a patient with nocardiosis. Image courtesy of Applied Radiology, Anderson Publishing, LTD.
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Chest CT scan in a patient with pleuropulmonary nocardiosis. Image courtesy of Applied Radiology, Anderson Publishing, LTD.
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Brain CT scan in a patient with nocardial brain abscess. Image courtesy of Applied Radiology, Anderson Publishing, LTD.
