Nocardia infection

Definition

Nocardia infection is a rare disorder affecting the lungs, brain, or skin. It occurs mainly in people with weakened immune systems.

Alternative Names

Nocardiosis

Causes, incidence, and risk factors

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

Nocardia bacteria are found in soil around the world. You can get the disease by inhaling contaminated dust or if soil containing nocardia bacteria gets into an open wound.

While individuals with normal immune systems can get this infection, the main risk factors for getting nocardiosis are a weakened immune system or chronic lung disease. People on long-term 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.

• Lungs (pulmonary nocardiosis):
  • Chest pain when breathing (may occur suddenly or slowly)
  • Coughing up blood
  • Fevers
  • Night sweats
  • Weight loss
• Brain (cerebral nocardiosis):
  • Fever
  • Headache
  • Loss of neurological function (depending on the part of the brain affected)
• Skin:
  • May become chronically infected (mycetoma) and develop draining tracts
  • Ulcers or nodules with infection sometimes spreading along lymph nodes

Some people with nocardia infection have no symptoms.

Signs and tests

Nocardia infection should be suspected in people with lung, brain, or skin symptoms if they also have a condition or conditions that weaken the immune system.

Nocardiosis is diagnosed using tests that identify the bacteria. Depending on the part of the body infected, testing may involve taking a tissue sample by:

• Brain biopsy
• Bronchoscopy
• Lung biopsy
• Skin biopsy
• Sputum culture

Treatment

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

In addition, patients who develop abscesses caused by this infection may need surgery to completely drain the abscesses.

Expectations (prognosis)

How well a person does depends on the parts if the body involved. There is a significant death rate if more than one site is involved (disseminated nocardiosis). In addition, an individual's immune system plays a large role in how well they will do.

Complications

Complications of nocardial infections vary depending on what parts of the body are involved. Certain lung infections may lead to scarring and chronic shortness of breath. Skin infections may lead to scarring or 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 symptoms that can have many causes other than nocardial infections. If you have lung, skin, or brain symptoms -- particularly if you have a weakened immune system -- tell your doctor. You will need to be evaluated for several potential infections, including nocardia.

References

Sorrell TC, Mitchell DH, Iredell JR. Nocardia species. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2005: chap 252.

Southwick FS. Nocardiosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 351.