Aspergillosis is an infection or an allergic response caused by a fungus of the Aspergillus type. It may play a role in allergy, but is best known for causing serious pulmonary infections in immunocompromised patients, e.g. those on chemotherapy.

Causes, incidence, and risk factors

Aspergillosis is caused by a fungus (Aspergillus), which is commonly found growing on dead leaves, stored grain, compost piles, or in other decaying vegetation.

It causes illness in three ways:

• as an allergic reaction in people with asthma (pulmonary aspergillosis - allergic bronchopulmonary type)
• as a colonization and growth in an old healed lung cavity from previous disease (such as tuberculosis or lung abscess ) where it produces a fungus ball called aspergilloma
• as an invasive infection with pneumonia that is spread to other parts of the body by the bloodstream (pulmonary aspergillosis - invasive type).

The invasive infection can affect the eye, causing blindness, and any other organ of the body, but especially the heart, lungs, brain, and kidneys. The third form occurs almost exclusively in people who are immunosuppressed because of cancer, AIDS, leukemia, organ transplants, high doses of corticosteroid drugs, chemotherapy, or other diseases that reduce the number of normal white blood cells.

Symptoms

Symptoms of allergic aspergillosis:

• Fever
• Malaise
• Coughing
• Coughing up blood or brownish mucous plugs
• Wheezing
• Weight loss
• Recurrent episodes of lung obstruction

Symptoms of invasive infection:

• Fever
• Chills
• Headaches
• Cough
• Shortness of breath
• Chest pain
• Increased sputum production, which may be bloody
• Bone pain
• Blood in the urine
• Decreased urine output
• Weight loss
• Symptoms involving specific organs
  • Brain: meningitis
  • Eye: blindness or visual impairment
  • Sinuses: sinusitis
  • Heart: endocarditis

Signs and tests

Aspergillosis is detected by:

• Abnormal chest X-ray or CT scan
• Sputum stain and culture showing Aspergillus
• Tissue biopsy (see bronchoscopy with transtracheal biopsy ) for aspergillosis
• Aspergillus antigen skin test
• Aspergillosis precipitin antibody or galactomannan positivity
• Elevated serum total IgE (immunoglobulin)
• Peripheral eosinophilia with allergic disease

Treatment

The goal of treatment is to control symptomatic infection. A fungus ball usually does not require treatment unless bleeding into the lung tissue is associated with the infection; then, surgical excision is required.

Invasive aspergillosis is treated with several weeks of intravenous amphotericin B, an antifungal medication. Itraconazole can also be used, or its newer counterpart voriconazole .

Endocarditis caused by Aspergillus is treated by surgical removal of the infected heart valves and long-term amphotericin B therapy.

Allergic aspergillosis is treated with oral prednisone. Some people may benefit from allergy desensitization . Antifungal agents do not help people with allergic aspergillosis.

Prognosis

Gradual improvement is seen in patients with allergic aspergillosis. Invasive aspergillosis may resist drug treatment and progress to death. The underlying disease and immune status of a person with invasive aspergillosis will also affect the overall prognosis.

Complications

• Amphotericin B can cause kidney impairment and severely unpleasant side effects.
• Invasive lung disease can cause massive bleeding from the lung.

Prevention

Caution has to be taken by patients known to be immunosuppressed. Be cautious in the use of drugs that suppress the immune system. Prevention of AIDS prevents opportunistic diseases, including aspergillosis, that are associated with a damaged or incompetent immune system.

Nosocomial aspergillosis

Nosocomial infection is defined as the acquisition of clinical infection as a result of medical intervention, and is usually applied to infections acquired in hospital.

Due to almost constant need for updating and expanding of medical services, renovation and construction are common occurrences in health care facilities. Fungal spores are released during repair, maintenance and construction. The spores are small and stay airborne for considerable periods of time. They may also spread long distances. Exposure to fungal spores constitutes a very serious threat to immunocompromised patients. Water and moisture damage also occur often in hospitals. This may create fungal reservoirs that may lead to adverse health effects even among personnel.

Many of the environmental hazards contributing to invasive aspergillosis have been identified, including unfiltered air, defects in hospital ventilation systems, food items, and possibly hospital water supplies. Stringent environmental controls in transplant units have included high-efficiency air filtration, positive-pressure ventialtion and frequent room air changes. Although there have been several well-documented examples of aspergillosis outbreaks as a result of hospital demolition and reconstruction, it has not always been possible to demonstrate elevated spore counts in clinical areas during building work. Furthermore, the possibility of community-acquired aspergillosis must be considered. These risks can usually be effectively minimized. However, very few studies have linked environmental exposure to cases of invasive aspergillosis

The exposure pathways regarding nosocomial yeast infections include carriage on healthcare workers hands, contaminated surfaces and medical devices. The environment also may become contaminated with yeasts, but the relative importance of this reservoir is unknown.

Finally, it must be stressed that nursing and medical staff should be educated in the special risks faced by the immunocompromised patient from the normal environment.

The most important nosocomial infection due to Aspergillus spp. is pneumonia.

Source

• MedlinePlus article

External links

• http://www.emedicine.com/PED/topic148.htm
• Prevention of nosocomial aspergillosis.
• The Impact of Culture Isolation of Aspergillus Species: A Hospital-Based Survey of Aspergillosis.
• CDC: Aspergillosis.
• CDC: Aspergillosis :Prevention of Nosocomial Pneumonia.
• Guidelines for Preventing Health-Care--Associated Pneumonia, Aspergillosis.
• CDC - Cerebral Aspergillosis Caused by Neosartorya hiratsukae, Brazil.