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Mucormycosis

Definition, Description, Causes and symptoms, Diagnosis, Treatment, Prognosis, Prevention

Mucormycosis is a rare but often fatal disease caused by certain fungi. It is sometimes called zygomycosis or phycomycosis. Mucormycosis is an opportunistic infection that typically develops in patients with weakened immune systems, diabetes, kidney failure, organ transplants, or chemotherapy.

Description

In the United States, mucormycosis is most likely to develop in the patient's nasal area or in the lungs.

Rhinocerebral mucormycosis

Rhinocerebral mucormycosis is an infection of the nose, eyes, and brain. The fungus destroys the tissue of the nasal passages, sinuses, or hard palate, producing a black discharge and visible patches of dying tissue. The fungus then invades the tissues around the eye socket and eventually the brain.

Pulmonary mucormycosis

Most patients with the pulmonary form of the disease are being treated for leukemia. The fungus enters the patient's lungs, where it eventually invades a major blood vessel, causing the patient to cough up blood or hemorrhage into the lungs.

Causes and symptoms

Mucormycosis is caused by fungi of several different species, including Mucor, Rhizopus, Absidia, and Rhizomucor. When these organisms gain access to the mucous membranes of the patient's nose or lungs, they multiply rapidly and invade the nearby blood vessels. The fungi destroy soft tissue and bone, as well as the walls of blood vessels.

The early symptoms of rhinocerebral mucormycosis include fever, sinus pain, headache, and cellulitis. As the fungus reaches the eye tissues, the patient develops dilated pupils, drooping eyelids, a bulging eye, and eventually hemorrhage of the blood vessels in the brain—causing convulsions, partial paralysis, and death.

The symptoms of pulmonary mucormycosis include fever and difficulty breathing, with eventual bleeding from the lungs.

Diagnosis

Diagnosis is usually based on a combination of the patient's medical history and a visual examination of the nose and throat. The doctor will take a tissue sample for biopsy, or a PAS, potassium hydroxide (KOH), or Calcofluor stain in order to make a tentative diagnosis. Confirmation requires a laboratory culture.

Imaging studies are not needed to make the diagnosis. If the patient has mucormycosis, however, magnetic resonance imaging (MRI) and computed tomography scans (CT scans) will usually show the destruction of soft tissue or bone in patients with advanced disease. Chest x rays will sometimes show a cavity in the lung or an area filled with tissue fluid if the patient has pulmonary mucormycosis.

Treatment

Treatment is usually begun without waiting for laboratory reports because of the rapid spread and high mortality rate of the disease. It includes intravenous amphotericin B (Fungizone); surgical removal of infected tissue; and careful monitoring of the disorder or condition that is responsible for the patient's vulnerability.

Prognosis

The prognosis for recovery from mucormycosis is poor. The mortality rate is 30%-50% of patients with the rhinocerebral form, and even higher for patients with pulmonary mucormycosis. The disease is almost 100% fatal for patients with AIDS.

Prevention

Prevention depends on protecting high-risk patients from contact with sugary foods, decaying plants, moldy bread, manure, and other breeding grounds for fungi.

Resources

BOOKS

Beavis, Kathleen G. "Systemic Mycoses." In Current Diagnosis. Vol. 9. Ed. Rex B. Conn, et al. Philadelphia: W. B. Saunders Co., 1997.

Hamill, Richard J. "Infectious Diseases: Mycotic." In Current Medical Diagnosis and Treatment, 1998. 37th ed. Ed. Stephen McPhee, et al. Stamford: Appleton & Lange, 1997.

"Infectious Disease: Systemic Fungal Diseases." In The Merck Manual of Diagnosis and Therapy. 16th ed. Ed. Robert Berkow. Rahway, NJ: Merck Research Laboratories, 1992.

Jackler, Robert K., and Michael J. Kaplan. "Ear, Nose, & Throat." In Current Medical Diagnosis and Treatment, 1998. 37th ed. Ed. Stephen McPhee, et al. Stamford: Appleton & Lange, 1997.

Rebecca J. Frey

KEY TERMS


Amphotericin B—An antibiotic used to treat mucormycosis and other severe fungal infections.

Opportunistic infection—An infection that develops only when a person's immune system is weakened.

Orbit—The bony cavity or socket surrounding the eye.

Zygomycosis—Another term for mucormycosis. The fungi that cause mucormycosis belong to a group called Zygomycetes.

Additional topics

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