• A rare infectious disease caused by Nocardia spp. which are primarily located in ground and water sources
  • No pathognomonic presentation
  • Nocardiosis can be acute, subacute, or chronic, and involves multiple systems:
    • Pulmonary (>70% overall, 39% only lung)
    • Disseminated: ≥2 sites (32% overall)
    • Cutaneous (~8%)
    • CNS (20% overall, 44% of disseminated, 9% brain only)
  • Patients are typically immunocompromised or have chronic pulmonary or systemic disease.
  • Less commonly, Nocardia can infect the eye, heart, bone, soft tissues, and any other organ system.


  • Overall: 0.4/100,000 cases per person-years
  • >60% are immunocompromised.
  • All ages are susceptible; mean age at diagnosis is in 4th decade of life.
  • Male > female (3:1)
  • ~500 to 1,000 cases per year in United States; not reportable
  • HIV/AIDS: 53/100,000 cases per person-years
  • Bone marrow transplant recipients: 128/100,000 cases per person-years
  • Solid-organ transplant recipients: 1,122/100,000 cases per person-years

Etiology and Pathophysiology

  • Nocardia spp. are aerobic gram-positive branching rods found worldwide in soil, decaying plants, fresh and salt water.
  • >80 species, >30 of which cause human disease.
  • Nocardia asteroides complex causes the majority of symptomatic infections and includes Nocardia abscessus, Nocardia cyriacigeorgica, Nocardia farcinica, and Nocardia nova.
  • Nocardia enters through inhalation (e.g., contaminated dust), traumatic skin inoculation, or ingestion.
  • Nocardiosis of the skin has four patterns: primary cutaneous, lymphocutaneous, cutaneous secondary to disseminated spread, and mycetoma.
  • Pulmonary, CNS, and other organ system infection with Nocardia is typically suppurative, often leading to abscess formation.
  • Incubation period: days to weeks
  • Pathologic Nocardia spp. have several intrinsic means of overcoming host immune responses.

Risk Factors

  • Most cases occur in immunocompromised hosts, particularly those with impaired cell-mediated immunity. Other chronic diseases (e.g., diabetes mellitus [DM], COPD) may predispose individuals to nocardiosis.
  • Farm workers and other immunocompetent individuals may develop pulmonary, cutaneous, and disseminated disease if sufficiently exposed.
  • Nocardiosis can be severe and fatal in immunocompromised patients; immunocompetent individuals rarely develop severe disease.
  • Immunocompromised children are also at risk.

Commonly Associated Conditions

  • Chronic pulmonary disease
  • Hematologic and other malignancies
  • Bone marrow and solid-organ transplantation
  • Chronic corticosteroid therapy
  • Autoimmune diseases
  • Tumor necrosis factor therapy
  • Kidney failure
  • Cirrhosis and alcoholism
  • Hypogammaglobulinemia
  • DM
  • TB and other granulomatous disease

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