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Nocardiosis is a serious infection caused by a fungus-like bacterium that begins in the lungs and can spread to the brain.


Nocardiosis is found throughout the world among people of all ages, although it is most common in older people and males. While people with poor immunity are vulnerable to this infection, it sometimes strikes individuals with no history of other diseases. Nocardiosis is rare in AIDS patients. It is not transmitted by person-to-person contact.

Causes and symptoms

Nocardiosis is caused by a bacterium of the Nocardia species—usually N. asteroides, an organism that is normally found in the soil. The incubation period is not known, but is probably several weeks.
The bacteria can enter the human body when a person inhales contaminated dust. Less often, people can pick up the bacteria in contaminated puncture wounds or cuts.


The infection causes a cough similar to pneumonia or tuberculosis, producing thick, sometimes bloody, sputum. Other symptoms include chills, night sweats, chest pain, weakness, loss of appetite and weight loss. Nocardiosis does not, however, respond to short-term antibiotics.


In about one-third of patients, the infection spreads from the blood into the brain, causing brain abscesses. This complication can trigger a range of symptoms including severe headache, confusion, disorientation, dizziness, nausea and seizures, and problems in walking. If a brain abscess ruptures, it can lead to meningitis.
About a third of patients with nocardiosis also have abscesses in the skin or directly underneath the skin. They may also have lesions in other organs, such as the kidneys, liver, or bones.


Nocardia is not easily identified from cultures of sputum or discharge. A doctor can diagnose the condition using special staining techniques and taking a thorough medical history. Lung biopsies or x rays also may be required. Up to 40% of the time, however, a diagnosis can't be made until an autopsy is done.


Treatment of nocardiosis includes bed rest and high doses of medication for a period of 12 to 18 months, including sulfonamide drugs or a combination of trimethoprim-sulfamethoxazole (Bactrim, Septra). If the patient doesn't respond to these drugs, antibiotics such as ampicillin (Amcill, Principen) or erythromycin (E-Mycin, Eryc) may be tried.
The abscesses may need to be drained and dead tissue cut away. Other symptoms are treated as necessary.


Nocardiosis is a serious disease with a high mortality rate. If it has been diagnosed early and caught before spreading to the brain, the prognosis is better. Even with appropriate treatment, however, the death rate is still 50%. Once the infection reaches the brain, the death rate is above 80%. This outcome is most commonly seen in patients with a weakened immune system.

Key terms

Abscess — A localized area of infection in a body tissue. Abscesses in the brain or skin are possible complications of nocardiosis.
Meningitis — An infection of the outer covering of the brain (meninges) that can be caused by either bacteria or a virus.



Orris, June, editor. Handbook of Diseases. Springhouse, PA: Springhouse Corp., 1996.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


infection with Nocardia.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


A generalized disease in humans and other animals caused by Nocardia asteroides, N. otitidiscaviarum, N. transvalensis, and N. brasiliensis; characterized by primary pulmonary lesions that may be subclinical or chronic with hematogenous spread to deep viscera, including the central nervous system; most commonly occurs in immunosuppressed patients.
Synonym(s): nocardiasis
Farlex Partner Medical Dictionary © Farlex 2012


Infectious disease Infection with Nocardia spp, in particular, N asteroides, which usually presents as a suppurative abscessing lesion of skin and lungs; dissemination to the brain is usually fatal
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


A generalized disease in humans and other animals caused by Nocardia asteroides and N. brasiliensis; characterized by primary pulmonary lesions that may be subclinical or chronic with hematogenous spread, and usually with involvement of the central nervous system.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Infection by the soil bacterium Nocardia asteroides and other species of the same genus. Nocardiosis often affects the foot and features persistent discharging abscesses (MADURA FOOT). In people with reduced resistance to infection (immunodeficiency) abscesses occur in the lungs and in other parts of the body, including the bowels and the brain. Treatment is with antibiotics.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


Edmund I.E., French veterinarian, 1850-1903.
Nocardia - a genus of aerobic nonmotile actinomycetes (family Nocardiaceae, order Actinomycetales), transitional between bacteria and fungi, which are mainly saprophytic but may produce disease in human beings and other animals.
Nocardia brasiliensis
Nocardia dacryoliths - white pseudoconcretions, composed of masses of Nocardia species found in the lacrimal canaliculi. Synonym(s): Desmarres dacryoliths
Nocardiasis bovine farcy
Nocardiaceae - a family of acid-fast, gram-positive, aerobic bacteria (order Actinomycetales) that includes the genus Nocardia.
nocardiosis - a pulmonary or brain infection that is caused by Nocadia asteroides.
Preisz-Nocard bacillus - see under Preisz
Medical Eponyms © Farlex 2012


Generalized disease caused by Nocardia asteroides and other species; characterized by primary pulmonary lesions that may be subclinical or chronic with hematogenous spread to deep viscera, including central nervous system; most common in immunosuppressed patients.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
A case series and focused review of nocardiosis: clinical and microbiologic aspects.
In as much as nocardiosis resembling tuberculosis, first-line antituberculous drugs are not efficient for its treatment.
Due to a low prevalence of nocardiosis, there are no definitive clinical studies on the most effective antibiotics.
Nocardiosis is mostly an opportunistic infection caused by Gram-positive aerobic bacteria belonging to the genus Nocardia.
The patient was diagnosed as pulmonary nocardiosis and secondary HLH.
At our institution, this was the first time MALDI-ToF had been used for rapid identification of pulmonary nocardiosis. This mass spectrometry methodology allowed for a significant reduction in the time to diagnosis (Figure 3).
Most cases of disseminated or pulmonary nocardiosis are associated with Nocardia asteroides and have also been previously described to be associated with COP.
Kerl, "Actinomycosis and nocardiosis," Compendium on Continuing Education for the Practising Veterinarian, vol.
Differential diagnosis further includes Staphylococcal mastitis with abscess, tuberculosis, and nocardiosis. Therefore, actinomycosis presents a diagnostic challenge.