Nocardiosis: what is it, symptoms, treatment, prognosis

general information

Nocardiosis Is an infection (usually of the lungs) characterized by abscesses in the lungs. These abscesses can spread through the chest wall. The infection is spread throughout the body through the blood by gram-positive bacteria called Nocardia.

• Bacteria Nocardia can infect the lungs if inhaled, and they can infect the skin if ingested through a cut or scratch.
• Symptoms depend on whether the bacteria infect the lungs (typically causing cough, fever, chills, chest pain, weakness, and loss of appetite) or skin (abscesseswhich can drain pus 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 for culture.
• Nocardiosis is treated with one or more antibiotics.

Infection in humans is caused by several types Nocardia. Nocardia asteroides usually causes infections of the lungs and the whole body. Other species commonly cause skin infections, especially in people living in tropical climates.

People become infected when:

• they inhale dust containing bacteria Nocardiathat leads to lung infection;
• soil or water containing bacteria enters the skin through a cut or scratch, resulting in a skin infection.

Nocardiosis is rarely transmitted from person to person.

Bacteria Nocardia can spread to nearby tissues or through the bloodstream, infecting any organ. They most commonly infect the brain, skin, kidneys, bones, or muscles. Abscesses (accumulations of pus) can form in infected organs.

Nocardiosis occurs worldwide in people of all ages. But it is more common among older people, especially men, and people with weakened immune systems. Any of the following disorders that weaken the immune system increase the risk of contracting nocardiosis:

• the presence of certain cancers (such as Hodgkin's lymphoma);
• the presence of a transplanted organ;
• taking high doses corticosteroids and / or other drugs that suppress the immune system;
• lung disease;
• late stage HIV /AIDS.

Nocardiosis is considered an opportunistic infection because it occurs in people with weakened immune systems. However, about 20-30% of people with nocardiosis do not have a disorder or disease that increases the risk of infection.

An estimated 500 to 1000 new cases of nocardiosis occur each year in the United States alone.

Signs and symptoms

Most cases of nocardiosis begin with lung infections that progress to lung abscesses. Symptoms of nocardiosis may include:

• chest pain;
• cough;
• bloody sputum;
• sweating;
• chills;
• weakness;
• lack of appetite;
• weight loss;
• labored breathing (dyspnea).

Symptoms of nocardiosis are similar to symptoms pneumonia and pulmonary tuberculosis.

The infection can spread through the bloodstream, resulting in abscesses in the brainwhere they are really very serious, or less commonly in the kidneys, intestines, or other organs. About one third of reported cases develop brain abscesses if left untreated or if treatment is delayed. Symptoms associated with brain abscesses can include severe headache and focal, sensory and motor abnormalities.

Cutaneous abscesses occur in about one third of all cases of nocardiosis and are usually found scattered throughout the arm, chest wall, and buttocks. In patients whose immune system is depressed due to HIV infection or corticosteroids or cytotoxic drugs, ulcerative colitis, a malignant tumor of the lymphatic system or a number of other diseases, the progression of the disease can be very rapid.

Nocardiosis can last from several months to years. It is important that the infection is diagnosed and differentiated from tuberculosis and pneumonia.

Causes and risk factors

Nocardiosis is often caused by Nocardia asteroides, a bacterium that enters the air from the ground and can be inhaled. Other species in the same family of bacteria, such as Nocardia brasiliensis, Nocardia caviae and Nocardia farcinicaalso cause disease. The bacterium usually enters the body through the lungs or, less commonly, through the gastrointestinal tract or cuts in the skin.

People whose immune systems are not functioning properly (immunocompromised) are at risk of developing nocardial infections. People whose immune systems are functioning properly but who take immunosuppressants as part of an organ transplant are also at greater risk than usual.

Affected populations

Nocardiosis occurs throughout the world. The victims tend to be older people, and men are more affected than women.

In the United States alone, 500-1000 new cases of nocardiosis are diagnosed annually.

Symptomatic disorders

Symptoms of the following disorders may be similar to those of nocardiosis. Comparisons can be useful for differential diagnosis:

• Actinomycosis is a chronic infectious disease characterized by drainage of the sinuses. The microorganisms that cause acitomycosis are often found on the gums, tonsils, and teeth. Actinomycosis most commonly affects adult males. The most common entry into the body of an infectious microorganism occurs through decayed teeth. Pulmonary or abdominal diseases can also occur due to this infection. The infection causes small abscesses that spread to the surrounding tissue. The abdominal form of the infection causes symptoms of pain, fever, vomiting, diarrhea or constipation and exhaustion. There may be an abdominal mass with signs intestinal obstructionand draining pus may develop in the abdominal wall. In chest infections, the infection may resemble tuberculosis with chest pain, fever, and a cough with phlegm.
• Tuberculosis Is an acute or chronic bacterial infection most commonly found in the lungs. The infection spreads as cold, mainly by airborne droplets, (i.e., through the inhalation of droplets in the air of a person infected with tuberculosis). In the lungs, tuberculosis causes respiratory distress, coughing and sputum production. Tuberculosis can also affect the kidneys, bones, lymph nodes, and membranes that surround the brain. Initial symptoms include fever, loss of appetite, weight loss, weakness, and dry cough. In later stages, symptoms may include coughing up blood.
• Pneumonia is a common bacterial infection of the lungs. The onset is sudden and usually manifests as fever and chills. Symptoms may include fever, pain or difficulty breathing, coughing, and phlegm. The fever rises rapidly, sometimes up to 40 degrees. There may also be nausea, vomiting, and a general feeling of unwell. Initially, there may be a dry cough, which later worsens and produces blood-streaked phlegm.

Diagnostics

Doctors can diagnose nocardiosis by looking for bacteria Nocardia in a sample of infected tissue examined under a microscope. Or they send a sample of infected tissue to a laboratory where a bacteriological study (culture on flora) is carried out to detect the bacteria Nocardiaif there is one. Doctors find infected tissue during a physical exam, x-ray, or other imaging test.

If bacteria are identified Nocardia an analysis is carried out to find an effective antibiotic (susceptibility testing procedure).

Standard treatments

Nocardia organisms are usually resistant to penicillin. Sulfonamide drugs may be prescribed. However, since most cases respond slowly, sulfonamide treatment should be continued for several months. Trimethoprim-sulfamethoxazole is often prescribed to treat immunocompromised patients. If people have a weakened immune system or an infection has spread, they need to take a second antibiotic.

Other drugs that are sometimes prescribed are Imipenem and cilastatin (Primaxin), Meropenem (Merrem IV), Cefotaxime (Claforan), Ceftriaxone (Rocefin), ampicillin, minocycline, and amikacin. Without treatment, the disease can be fatal, so correct and prompt diagnosis is necessary.

If infection occurs and spreads, surgery may be required to remove and / or drain the infected area.

Forecast

If left untreated, nocardiosis that affects the lungs or has spread throughout the body is usually fatal. With appropriate treatment, people with abnormal immune systems have a 10% risk of death, especially if the infection only affects the lungs. But even with treatment, more than half of people with weakened immune systems die.

Skin infections resolve in most people after antibiotic treatment.