Mycetoma of the foot is a chronic infectious disease of the feet caused by fungi and bacteria. Specific to the pathology is the formation of granuloma with subsequent damage to fascia, muscles, bones and ligaments. Deformities of bones and joints, painless edema, formation of fistulous passages are characteristic. Diagnostic procedures include examination of biopsy and fistula discharge, radiography of the foot. Treatment is carried out using etiotropic (antimycotic, antibacterial) agents and symptomatic (vasoprotectors, detoxification) drugs. Local physiotherapy and surgical treatment is often required.
Mycetoma (Madura foot, maduromycosis, maduromycetoma) is an invasive process affecting mainly the soft tissues of the distal parts of the lower extremities. The first mention of this disease is found in the Indian Vedas, a description of the pathology was made in the city of Madura (India) in 1842. Mycetoma is widespread everywhere, but unevenly – the most dangerous regions are considered to be the arid regions of Africa and India, the disease is somewhat less common in Japan, Saudi Arabia, Canada, Europe, and Russia. Men aged 20-40 who work in agriculture are more likely to get sick. There is no clear seasonality.
The causative agents of the disease are fungi (eumycetes) and bacteria (actinomycetes). In the wild, fungi live in moist soil, manure, humus, coastal silt, on the surface of plants. There are more than 20 types of pathogens that can cause maduromycosis. The source of bacterial infection becomes a sick person, for the spread of the pathogen requires a long close contact of the patient’s skin area with another person’s skin area. Usually, the transmission of a pathogenic microorganism occurs with a traumatic violation of the integrity of the skin (punctures, abrasions, scratches). Risk factors are immunodeficiency conditions, pregnancy, disorders of venous blood supply, neuropathy of the feet, working with soil in greenhouses, greenhouses, rubbing bare skin with straps and straps, walking barefoot.
In the area of the entrance gate of infection in the thickness of the dermis, granuloma is formed – a cluster of lymphocytes around the pathogen. Initially, the granuloma does not exceed millet grain in size, but over time it increases and germinates the surrounding tissues: subcutaneous tissue, muscles, tendons, bones. As a result, microabcesses occur, fibrous tissue overgrowth and the formation of tubercular infiltrates are observed. Trophic disorders due to an increase in the amount of connective tissue contribute to the appearance of dense edema. Nodes can ulcerate with the formation of fistula passages. The discharge is succulent, odorless (except in cases of bacterial infection), contains a pathogen. Further formation of edema, infiltrates contributes to the thinning of the articular bag and periosteum, bone tissue damage.
Depending on the place of penetration of the pathogen, maduromycosis can affect not only the feet, but also the hands, scalp, neck, back, chest, however, the most frequent manifestation of invasion is unilateral lesion of the distal extremities (about 85% of cases). Taking into account the type of pathogen, two types of foot mycetoma are distinguished, which at the initial stages practically do not differ from each other in clinical manifestations:
- Eumycetoma. It accounts for about half of the cases of Madura foot in the world and 80% in Africa. With a long course (for decades), hyperpigmentation of the skin of the foot, deformity of the limb, atrophy of the muscles of the lower leg is noted. Bone destruction is rarely observed.
- Actinomycetoma. A malignant variant of mycetoma. This form is characterized by the formation of fistulas, scarring, bone deformation, disfiguration of the foot. A significant part of the cases of disability falls on this type of disease.
The incubation period ranges from 30 days to 1 year or more. The disease begins gradually, fever and painful sensations are uncharacteristic. Sometimes patients notice itching in the extremity, increasing swelling. Then the foot increases, acquires a bluish-purple hue, loses its shape due to the appearance of tuberosity, indurative edema. The nodes gradually increase in size, become compacted, ulcers with a transparent detachable may appear on the surface. In the future, there is stiffness, soreness during movements in the ankle joint, metatarsal, phalangeal joints, lameness.
The addition of secondary bacterial flora is manifested by the appearance and increase of fever, chills, weakness, increased edema, restriction of movements. The pain in the limb becomes intense, purulent contents with a fetid odor are released from the fistulas. With a long-running actinomycetoma, anemia is detected due to the presence of a chronic disease and accompanied by drowsiness, weakness, pallor of the skin, brittle nails and hair, constipation, taste perversions.
The prolonged course of the disease contributes to the occurrence of destructive changes in bones and soft tissues, disability of the patient. The most common complications of pathology are osteomyelitis, arthritis, tendovaginitis, phlegmon, abscesses, sepsis. The presence of a focus of chronic inflammation in the body may eventually lead to amyloidosis of internal organs. Localization of the process on the lower extremities predisposes to thromboembolic complications. With deep immunosuppression, AIDS, sometimes there is fungemia and bacteremia with the formation of purulent foci in the internal organs. Possible endocarditis, endophthalmitis.
The diagnosis is verified based on the conclusions of an infectious disease specialist, surgeon, dermatologist, and the results of objective studies. Careful collection of anamnesis is also important, special attention is paid to trips to endemic areas and the nature of the patient’s work activity. Mandatory diagnostic manipulations are:
- Objective inspection. Physical data are scarce, sometimes pallor, dryness of the skin, shortness of breath, cracks in the corners of the mouth, perversion of taste, drowsiness are found. Examination of the foot reveals the presence of indurative edema, tuberosity, thickening of the fingers, bluish skin tone, ulceration in the area of the tubercles with the formation of fistulas. Palpation is painless.
- Laboratory tests. Blood test confirms the acceleration of ESR, with the addition of a secondary infection, leukocytosis with a rod-shaped shift to the left is determined, with a prolonged course – anemia. Biochemical parameters are within normal limits, sometimes there is an increase in the level of CRP. General clinical examination of urine – without pathology.
- Identification of infectious agents. Identification of the pathogen is carried out by microscopic examination of the fistula discharge (search for fungal druses), sowing on nutrient media, histological description of the biopsy (druses with abscess zones). PCR provides a fast and accurate result, which is especially important when receiving negative results of the culture method.
- Visualization techniques. Radiography of the foot bones indicates the presence of destructive changes: “punch holes”, areas of osteolysis, osteosclerosis. The characteristic symptom of “dots in a circle” during MRI is described. Ultrasound examination of the foot reveals thickening of the skin, subcutaneous fat layer due to infiltrative edema, fistulous passages, deformation, destruction of the structure of the metatarsal bones.
Differential diagnosis of mycetoma of the foot is carried out with erysipelas, cutaneous leishmaniasis, tuberculosis, Kaposi’s sarcoma, botryomycosis, tertiary syphilis, chronic venous insufficiency, deep vein thrombosis, trophic ulcers, lymphedema, abscesses, phlegmon, malignant neoplasms, chronic osteomyelitis, arthritis.
Patients with of mycetoma of the foot are non-contagious, can be treated on an outpatient basis. Inpatient management of patients is recommended in the presence of pregnancy, severe concomitant pathology. The diet is not provided, it is recommended to have a full meal with a large amount of meat, dairy, grain products. Bed rest is required only for severe pain syndrome, fever. It is necessary to limit the thermal effects and traumatization of the foot, wear comfortable shoes, socks with elastic bands, to reduce swelling, give the limb an elevated position.
The course of treatment is 10 months or more, the selection of etiotropic drugs is made after determining the type of pathogen and its sensitivity to drugs. With actinomycetoma, antibiotics are used (penicillins, cephalosporins, tetracyclines, aminoglycosides, sulfonamides), with eumycetoma – antifungal drugs (terbinafine, itraconazole, ketoconazole). Detoxification (glucose-salt solutions), vasoprotectors (rutoside), washing of fistula passages with a solution of hydrogen peroxide are recommended. Surgical excision of the foot mycetoma is usually performed in the form of opening and drainage of abscesses. With total destruction of bones and soft tissues, amputation is indicated. Physiotherapy measures include ultrasound therapy with potassium iodide.
Prognosis and prevention
The prognosis with timely diagnosis and adequate treatment is favorable, with a long course, disability of the patient is possible. The average duration of the disease is 6-20 years. In some cases, relapses are noted. Deaths are associated with severe immunosuppression, the addition of bacterial infections, septic complications. It is proved that the bacterial etiology of the disease leads to a more severe course. Preventive vaccines have not been developed. Non-specific preventive measures are reduced to preventing foot injuries, treating cuts, punctures, abrasions of soles with antiseptic solutions, wearing comfortable closed shoes when working with soil, caring for animals. People with immunodeficiency receiving immunosuppressive therapy should be aware of the danger of infection, they are advised to avoid traveling to endemic areas.