Mycetoma is a chronic infection in the skin caused by either bacteria (

actinomycetoma Actinomycetoma is a chronic bacterial subcutaneous infection caused by '' Actinomyces'' that affect the skin and connective tissue. It is, therefore, a form of actinomycosis. Mycetoma is a broad term which includes actinomycetoma and eumycetoma ...

) or fungi (

eumycetoma Eumycetoma, also known as Madura foot, is a persistent Mycoses, fungal infection of the skin and the tissues subcutaneous tissue, just under the skin, affecting most commonly the feet, although it can occur in hands and other body parts. It s ...

), typically resulting in a triad of painless firm skin lumps, the formation of weeping

sinuses Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the sphenoi ...

, and a discharge that contains grains. 80% occur in feet. Most eumycetoma is caused by ''M. mycetomatis'', whereas most actinomycetoma is caused by ''N. brasiliensis'', ''S. somaliensis'', ''A. madurae,'' and ''Actinomadura pelletieri''. People who develop mycetoma likely have a weakened

immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...

. It can take between 3 months to 50 years from the time of infection to first seeking healthcare advice. Diagnosis requires

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

and

fine needle aspiration Fine-needle aspiration (FNA) is a diagnostic procedure used to investigate lumps or masses. In this technique, a thin (23–25 gauge (0.52 to 0.64 mm outer diameter)), hollow needle is inserted into the mass for sampling of cells that, ...

. While most cases of mycetoma occur in Sudan, Venezuela, Mexico, and India, its true prevalence and incidence are not well-known. It appears most frequently in rural areas, particularly in farmers and shepherds, who are often men between 20 and 40 years old earning the primary income for their families. It has been reported since 1840. Noteworthy, the diagnosis of mycetoma in non-endemic or low endemic areas as Europe and North Africa is challenging. Physicians in these areas are usually unfamiliar with the disease-specific manifestations and need to exercise extra vigilance regarding those patients who are at high risk of contracting mycetoma infections. Recent evidence suggests that Egypt, which borders sub-Saharan Africa, is a low-endemic country. Additionally, recent evidence suggests that Pakistan, which borders India, is a moderate-endemic country. Unlike bacterial acute hematogenous osteomyelitis and septic arthritis, misdiagnosed or delayed diagnosis of mycetoma osteomyelitis can result in amputation or radical resection. The disease is listed by the

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

(WHO) as a

neglected tropical disease Neglected tropical diseases (NTDs) are a diverse group of tropical infections that are common in low-income populations in developing regions of Africa, Asia, and the Americas. They are caused by a variety of pathogens, such as viruses, bacteri ...

Risk

Frequent exposure to penetrating wounds by thorns or splinters is a risk factor. This risk can be reduced by disinfecting wounds and wearing shoes.

Pathogenesis

Mycetoma is caused by common

saprotrophs Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ...

found in the soil and on thorny shrubs in semi-desert climates. Some common causative agents are: * ''

Madurella mycetomatis ''Madurella mycetomatis'' is a fungus primarily reported in Central Africa as a cause of mycetoma in humans. It has been misclassified for many years, but with improvement of molecular techniques, its phylogenetic classification has been establ ...

'' (fungus) * ''

Nocardia brasiliensis ''Nocardia brasiliensis'' is a species of ''Nocardia''. As with most members of Actinomycetota, they contain high guanine and cytosine Cytosine () (symbol C or Cyt) is one of the four nucleotide bases found in DNA and RNA, along with ade ...

'' (bacteria) * '' Actinomadure madura'' (bacteria) * ''

Streptomyces somaliensis ''Streptomyces somaliensis'' is a proteolytic bacterium species from the genus of '' Streptomyces'' which has been isolated from a mycetoma from the foot of a man in Somalia Somalia, officially the Federal Republic of Somalia, is the eas ...

'' (bacteria) * ''

Actinomadura pelletieri The genus ''Actinomadura'' is one of four genera of Actinomycetota that belong to the family Thermomonosporaceae. It contains aerobic, Gram-positive, non-acid-fast, non-motile, chemo-organotrophic actinomycetes that produce well-developed, non ...

'' (bacteria) Infection is caused as a result of localized skin trauma, such as stepping on a needle or wood splinter, or through a pre-existing wound. The first visible symptom of mycetoma is a typically painless swelling beneath the skin; over several years, this will grow to a

nodule Nodule may refer to: * Nodule (geology), a small rock or mineral cluster * Manganese nodule, a metallic concretion found on the seafloor *Nodule (medicine), a small aggregation of cells *Root nodule Root nodules are found on the roots of plants, ...

(lump). Affected people will experience massive swelling and hardening of the area, in addition to skin rupture and the formation of sinus tracts that discharge pus and grains filled with organisms. In many instances, the underlying bone is affected. Some people with mycetoma will not experience pain or discomfort, while others will report itching and/or pain.

Diagnosis

There are currently no rapid diagnostic tools for mycetoma. Mycetoma is diagnosed through microscopic examination of the grains in the nodule and by analysis of

cultures Culture ( ) is a concept that encompasses the social behavior, institutions, and Social norm, norms found in human societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, Attitude (psychology), attitudes ...

. Since the bacterial form and the fungal form of mycetoma infection of the foot share similar clinical and radiological features, diagnosis can be a challenge. Magnetic resonance imaging is a valuable diagnostic tool. However, its results should be closely correlated with the clinical, laboratory, and pathological findings.

Treatment

Currently,

itraconazole Itraconazole, sometimes abbreviated ITZ, is an antifungal medication used to treat a number of fungal infections. This includes aspergillosis, blastomycosis, coccidioidomycosis, histoplasmosis, and paracoccidioidomycosis. It may be given ...

is used to treat mycetoma. Recent research found that

fosravuconazole Fosravuconazole (trade name Nailin) is a triazole antifungal agent. In Japan, it is approved for the treatment of onychomycosis, a fungal infection of the nail. It is a prodrug that is converted into ravuconazole. Drugs for Neglected Dise ...

can also treat the disease. While treatment will vary depending on the cause of the condition, it may include

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as ...

medication. Actinomycetoma, the bacterial form, can be cured with antibiotics. Eumycetoma, the fungal form, is treated with antifungals. Surgery in the form of bone resection may be necessary in late-presenting cases or to enhance the effects of medical treatment. In the more extensive cases amputation is another surgical treatment option. For both forms, extended treatment is necessary.

Epidemiology

Mycetoma is endemic in some regions of the tropics and subtropics. India, sub-Saharan Africa (e.g., Sudan), and Mexico are most affected. Pakistan is probably a moderate-endemic country. Sporadic cases have been reported across some North African countries. Egypt is probably a low-endemic country.

Other animals

In cats, mycetoma can be treated with complete surgical removal. Antifungal drugs are rarely effective.

References

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External links

DermNet NZ
an online resource about skin diseases from the New Zealand Dermatological Society Incorporated.
Orphanet
a reference portal from Europe that provides information on rare diseases and orphan drugs.
ClinicalTrials.gov
a list of clinical trials related to mycetoma. Animal fungal diseases Infectious diseases Tropical diseases Fungal diseases