MSD Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Nocardiosis

(Nocardia)

By

Larry M. Bush

, MD, FACP, Charles E. Schmidt College of Medicine, Florida Atlantic University

Last full review/revision Mar 2021| Content last modified Mar 2021
Click here for the Professional Version
  • Nocardia bacteria can infect the lungs when they are inhaled, and they can infect the skin when they enter the skin through a cut or scrape.

  • Symptoms depend on whether the bacteria infect the lungs (typically, causing a cough, fever, chills, chest pain, weakness, and loss of appetite) or the skin (abscesses, which may drain to the surface of the skin).

  • To diagnose nocardiosis, doctors examine a sample of infected tissue under a microscope or send the sample to a laboratory to be cultured.

  • Nocardiosis is treated with one or more antibiotics.

Several species of Nocardia infect people. Nocardia asteroides usually causes lung and bodywide infections. Another species usually causes skin infections, particularly in people who live in tropical climates.

People become infected when

  • They inhale dust that contains Nocardia bacteria, resulting in a lung infection.

  • Soil or water that contains the bacteria enters the skin through a cut or scrape, resulting in a skin infection.

Nocardiosis rarely spreads from person to person.

Nocardia bacteria can spread to nearby tissue or through the bloodstream to infect any organ. They most commonly infect the brain, skin, kidneys, bone, or muscle. Abscesses (pockets of pus) may form in the infected organs.

Nocardiosis occurs worldwide in people of all ages. But it is more common among older people, especially men, and in people who have a weakened immune system. Any of the following conditions, which weaken the immune system, increases the risk of getting nocardiosis:

Nocardiosis is considered an opportunistic infection because it occurs in people with a weakened immune system. However, about 20 to 30% of people with nocardiosis have no disorder or condition that increases the risk.

In the United States, an estimated 500 to 1,000 new cases of nocardiosis occur each year.

Symptoms of Nocardiosis

Symptoms of nocardiosis may be short-lived (acute) or become long-lasting (chronic).

Lung infection

If the lungs are infected, symptoms usually include cough, fever, chills, chest pain, weakness, loss of appetite, and weight loss.

Skin infection

If the skin is infected, abscesses often form in the skin or the tissues under the skin. The affected skin may be firm, red, warm, and tender to the touch. A lump that contains pus may form and spread under the skin or through the lymphatic vessels The lymphatic system is a vital part of the immune system. It includes organs such as the thymus, bone marrow, spleen, tonsils, appendix, and Peyer patches in the small intestine that produce... read more . Channels may form between the lump and the skin, and the pus may drain through them to the skin's surface.

Brain infection

In up to half of people with nocardiosis, the infection spreads to the brain, causing a collection of pus (abscess) to form. A brain abscess causes severe headaches and symptoms such as weakness, confusion, and seizures.

Diagnosis of Nocardiosis

  • Examination under a microscope or culture

Doctors may diagnose nocardiosis by identifying Nocardia bacteria in a sample of infected tissue examined under a microscope. Or they may send a sample of infected tissue to a laboratory where Nocardia bacteria, if present, can be grown (cultured) and identified. Doctors locate the infected tissue during a physical examination or on an x-ray or other imaging scan.

Prognosis of Nocardiosis

Without treatment, nocardiosis that involves the lungs or that has spread is usually fatal. Even with appropriate antibiotic treatment, about 10% of people with a weakened immune system whose infection affects only the lungs die, and more than 50% of people with a weakened immune system whose infection has spread die.

Skin infections resolve in most people after treatment with antibiotics.

Treatment of Nocardiosis

  • Antibiotics

Nocardiosis is treated with one or more antibiotics for several months or more. Trimethoprim/sulfamethoxazole is often used. If people have a weakened immune system or the infection has spread, they need to take a second antibiotic. Treatment is started before doctors get the test results. The antibiotics may later be adjusted based on the results of susceptibility testing.

Localized abscesses generally require incision, drainage, and surgical removal of dead tissue.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Test your knowledge

Dengue
Dengue is a viral infection that causes fever, aches throughout the body, and, in severe cases, bleeding in multiple areas. How is the dengue virus transmitted? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
TOP