Pulmonary nocardiosis

Definition

Pulmonary nocardiosis is an infection of the lung that is caused by the fungus-like bacterium Nocardia asteroides.

Causes, incidence, and risk factors

Nocardia infection develops when you inhale the bacteria. The infection causes pneumonia-like symptoms but is often not limited to the lungs. Infection can spread to any part of the body, but brain and skin infections are the most common complications.

In the US, there are 500-1,000 new cases of nocardia infection diagnosed each year.

People at highest risk for nocardia infection are people with impaired immune systems, including people with HIV, people receiving chronic therapy with steroid medication, and people who have received organ transplants. People suffering chronic lung problems related to smoking, emphysema, or other infections such as tuberculosis are also at increased risk.

Pulmonary (lung) manifestations of nocardiosis are more common in children than adults.

Symptoms

• Cough with sputum production
• Progressive difficulty breathing (pulmonary insufficiency)
• General discomfort, uneasiness, or ill feeling (malaise)
• Unintentional weight loss
• Fever (intermittent)
• Night sweats, excessive sweating at night
• Chest pain
• Joint pain
• Liver and spleen enlargement (hepatosplenomegaly)
• Headache, change in mental state (occurs with brain lesions)
• Skin rashes or lumps

Signs and tests

• Decreased breath sounds in the lung
• Crackles (rales) in the infected lung detected by stethoscope
• Chest x-ray
• CT scan
• Sputum stain and culture
• Bronchial alveolar lavage - fluid is sent for stain and culture
• Pleural fluid culture and stain
• Bronchoscopy

Treatment

The objective of treatment is to control the infection. Antibiotics are used, but the response to treatment may be slow and the medications must be continued for at least 6 months. Patients who have medication allergies will need to take alternative antibiotics.

Surgery may be needed to remove or drain infected areas.

Expectations (prognosis)

The probable outcome is generally good when diagnosis and treatment are prompt. Outcome is poor when the infection is widespread and treatment has been delayed.

Complications

• Invasion by lesions into the ribs
• Brain abscesses
• Infections of the skin

Calling your health care provider

Call your health care provider if symptoms of this disorder develop. Early diagnosis and treatment may possibly improve the chance of a good outcome.

Prevention

Caution when using corticosteroids may be helpful - these drugs should be used sparingly and in the lowest effective doses and for the shortest periods of time possible when they are needed.

Some patients with impaired immune systems may need to take antibiotics for long periods of time to prevent the infection from recurring.

Illustrations

Respiratory system

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Nocardiosis - pulmonary