Nocardiosis
GENERAL PRINCIPLES
• Nocardia is a ubiquitous group of aerobic gram-positive branching filamentous bacteria that causes severe local and disseminated disease in the setting of impaired cell-mediated immunity.
Nocardia can be differentiated from Actinomyces by AFB stain, as mycolic acid is present in the cell wall and it can grow under aerobic conditions.• Typical infection tends to be pulmonary infiltrate, abscess, or empyema, but dissemination is common and tends to favor CNS infection, causing abscess.
DIAGNOSIS
• Clinical presentation can be acute, subacute, or chronic pneumonia.
• Chest imaging can reveal a variety of findings such as infiltrates, nodules, pleural effusions, or cavities.39
• Diagnosis requires sputum or tissue Gram stain and culture (including AFB), often needing multiple samples because yields are low.
• Brain MRI is recommended to evaluate for concurrent CNS infection in patients with pulmonary disease.
TREATMENT
See Table 14-13.