Mycetoma

Definition

Mycetoma, or maduromycosis, is a slow-growing bacterial or fungal infection focused in one area of the body, usually the foot. For this reason--and because the first medical reports were from doctors in Madura, India--an alternate name for the disease is Madura foot. The infection is characterized by an abnormal tissue mass beneath the skin, formation of cavities within the mass, and a fluid discharge. As the infection progresses, it affects the muscles and bones; at this advanced stage, disability may result.

Description

Although the bacteria and fungi that cause mycetoma are found in soil worldwide, the disease occurs mainly in tropical areas in India, Africa, South America, Central America, and southeast Asia. Mycetoma is an uncommon disease, affecting an unknown number of people annually.

There are more than 30 species of bacteria and fungi that can cause mycetoma. Bacteria or fungi can be introduced into the body through a relatively minor skin wound. The disease advances slowly over months or years, typically with minimal pain. When pain is experienced, it is usually due to secondary infections or bone involvement.Although it is rarely fatal, mycetoma causes deformities and potential disability at its advanced stage.

Causes & symptoms

Owing to a wound, bacteria or fungi gain entry into the skin. Approximately one month or more after the injury, a nodule forms under the skin surface. The nodule is painless, even as it increases in size over the following months. Eventually, the nodule forms a tumor, or mass of abnormal tissue. The tumor contains cavities--called sinuses--that discharge blood- or pus-tainted fluid. The fluid also contains tiny grains, less than two thousandths of an inch in size. The color of these grains depends on the type of bacteria or fungi causing the infection.

As the infection continues, surrounding tissue becomes involved, with an accumulation of scarring and loss of function. The infection can extend to the bone, causing inflammation, pain, and severe damage. Mycetoma may be complicated by secondary infections, in which new bacteria become established in the area and cause an additional set of problems.

Diagnosis

The primary symptoms of a tumor, sinuses, and grain-flecked discharge often provide enough information to diagnose mycetoma. In the early stages, prior to sinus formation, diagnosis may be more difficult and a biopsy, or microscopic examination of the tissue, may be necessary. If bone involvement is suspected, the area is x-rayed to determine the extent of the damage. The species of bacteria or fungi at the root of the infection is identified by staining the discharge grains and inspecting them with a microscope.

Treatment

Combating mycetoma requires both surgery and drug therapy. Surgery usually consists of removing the tumor and a portion of the surrounding tissue. If the infection is extensive, amputation is sometimes necessary. Drug therapy is recommended in conjunction with surgery. The specific prescription depends on the type of bacteria or fungi causing the disease. Common medicines include antifungal drugs, such as ketoconazole and antibiotics (streptomycin sulfate, amikacin, sulfamethoxazole, penicillin, and rifampin).

Prognosis

Recovery from mycetoma may take months or years, and the infection recurs after surgery in at least 20% of cases. Drug therapy can reduce the chances of a re-established infection. The extent of deformity or disability depends on the severity of infection; the more deeply entrenched the infection, the greater the damage. By itself, mycetoma is rarely fatal, but secondary infections can be fatal.

Prevention

Mycetoma is a rare condition that is not contagious.

Key Terms

Biopsy

A medical procedure in which a small piece of tissue is surgically removed for microscopic examination.

Grains

Flecks of hardened material such as bacteria or fungi spores.

Nodule

A hardened area or knot sometimes associated with infection.

Secondary infection

Illness caused by new bacteria, viruses, or fungi becoming established in the wake of an initial infection.

Sinuses

Cavities or hollow areas.

Tumor

A mass or clump of abnormal tissue, not necessarily caused by a cancer.

Further Reading

For Your Information

Periodicals

• Fahal, A.H., and M.A. Hassan. "Mycetoma." British Journal of Surgery 79(November 1992): 1138.
• McGinnis, Michael R. "Mycetoma." Dermatologic Clinics 14(1)(January 1996): 97.
• Welsh, Oliverio. "Mycetoma." Seminars in Dermatology 12(4)(December 1993): 290.

Gale Encyclopedia of Medicine. Gale Research, 1999.