• Clinical science

Nocardiosis

Summary

Nocardiosis is a rare infection caused by Nocardia, a genus of aerobic, gram-positive bacteria. It manifests as either pulmonary, cutaneous, or disseminated disease. Pulmonary nocardiosis presents as a virulent form of pneumonia, which occurs more commonly in immunosuppressed individuals. As in any other type of pneumonia, productive cough, pleuritic chest pain, and fever are the dominant symptoms, making it difficult to differentiate from other lung infections. Cutaneous nocardiosis manifests with either cellulitis or purulent erythematous nodules. It may be accompanied by inflamed lymph nodes. The disseminated form predominantly occurs in immunocompromised patients and is typically associated with pulmonary or CNS involvement. A suspected diagnosis is confirmed via culture from infected material (e.g., sputum or skin samples). The mainstay of treatment is long-term antibiotic therapy with TMP/SMX. Without treatment, pulmonary nocardiosis and disseminated nocardiosis are usually fatal in immunocompromised patients.

Epidemiology

  • > (3:1) [1]
  • Pulmonary infection is the most common [2]
  • Systemic infection : the CNS is involved in up to 30% of cases [3]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Clinical features

Pulmonary nocardiosis [5]

Cutaneous nocardiosis

  • Primary infection
  • Cutaneous involvement
    • Originates from a disseminated focus or after trauma
    • Indiscernible from primary lesions, although features of underlying systemic disease (pneumonia, seizures, focal deficits) are present

Disseminated nocardiosis

  • Definition: two or more sites of involvement
  • Clinical features: generally involves both the lungs and the brain
    • Pulmonary findings are prominent.
    • Metastatic abscesses may be found almost anywhere but are predominantly located on the lower extremities.
    • CNS features: headache, lethargy, confusion, seizures, sudden onset of neurological deficits

The combination of pneumonia and abscess in the lower extremities is particularly suggestive of nocardiosis.

Diagnostics

Treatment

last updated 10/25/2020
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