Nocardia infection

Alternative names
Nocardiosis

Definition
Nocardia infection is a rare disorder caused by bacteria called nocardia, which tend to affect the lungs, brain, or skin. It occurs primarily in individuals with weakened immune systems.

Causes, incidence, and risk factors

Nocardia infection is a chronic bacterial infection that usually originates in the lungs and tends to spread to other organ systems - most commonly the brain and the skin. It may also involve the kidneys, the joints, the heart, the eyes, and the bones.

Nocardia is found in soil around the world. It can be contracted by inhaling contaminated dust or via contamination of a wound with soil containing nocardia.

While individuals with normal immune systems can acquire this infection, the main risk factors for nocardiosis are a weakened immune system or chronic lung disease. People on chronic steroid therapy, those with cancer, organ or bone marrow transplants, or HIV/AIDS are at risk.

Symptoms

Symptoms vary and depend on the organs involved.

     
  • Pulmonary (lung involvement):       o fevers       o night sweats       o Weight loss       o coughing blood       o chest pain upon breathing (may occur suddenly or slowly)  
  • Brain (cerebral nocardiosis):       o fever       o headache       o loss of neurological function (may be seen, depending the part of the brain affected)       o Some individuals may have no symptoms.  
  • Skin:       o ulcers and/or nodules with infection sometimes tracking along lymph node chains       o may become chronically infected (mycetoma) and develop draining tracts       o can progress down to muscle and bone

Signs and tests

Because nocardia infections are most likely to affect the lungs, brain, and skin, the diagnosis should be suspected in individuals who have symptoms characteristic of this disorder in any of those organs, particularly if they have immune disorders.

Nocardiosis is definitively diagnosed by identification of the bacteria in culture. Depending on the site involved this may involve obtaining a tissue sample for staining and culture by way of the following:

     
  • sputum culture  
  • bronchoscopy  
  • lung biopsy  
  • skin biopsy  
  • brain biopsy

Treatment

Long-term antibiotic therapy (usually with sulfonamides) for 6 months to a year (or longer depending on the individual and site involved) is needed to treat nocardia. Frequently, chronic suppressive therapy may be needed (prolonged, low-dose antibiotic therapy).

In addition, in patients with abscesses caused by this infection, surgery may be required in order to ensure adequate drainage.

Expectations (prognosis)
Prognosis depends on the sites involved. There is a significant mortality rate if more than 1 site is involved (disseminated nocardiosis). In addition, the degree of impairment of the individual’s immune system will affect the outcome.

Complications
Complications of nocardial infections are varied and depend on the site involved. Certain lung infections may lead to scarring, chronic Shortness of breath; skin infections may lead to scarring, disfigurement; brain abscesses may lead to loss of neurological function.

Calling your health care provider
Notify your medical provider if you have any of the symptoms described above - these are non-specific and may have numerous causes other than nocardial infections. Alert your provider if you have symptoms involving the lung, skin, or brain in any combination - in particular if you have a weakened immune system - as you should be evaluated for several potential infections, including nocardia.

Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

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