足菌肿

　　一、发病原因

　　主要病原菌为奴卡菌和足菌肿马杜拉菌。根据病原菌不同，足菌肿分为两类：

　　1、真菌性足菌肿(eumyceticmycetoma)：病原菌包括形成白色颗粒的镰状霉、雷氏枝孢霉、吉林支孢霉、构巢曲霉、黄曲霉、茄病镰孢、罗萨梯新龟甲形菌、假性阿利什霉(异名尖端赛多孢)，和形成黑色颗粒的新月弯孢、膝曲弯孢、甄氏外瓶霉、塞内加尔小球腔菌、汤普金斯小球腔菌、足菌肿马杜拉菌、灰马杜拉菌、罗麦卢棘壳孢和麦金诺棘壳孢。

　　2、放线菌性足菌肿(actinomyceticmycetoma)：It is caused by 8 species of Actinomycetes such as Nocardiobrasiliensis and Actinomadura madurae of the genus Actinomyces.

　　2. Pathogenesis

　　This disease is often caused by the invasion of fungi or actinomycetes from the natural environment into the deep dermis or subcutaneous tissue after trauma, and is characterized by chronic suppurative granuloma with granules formed by the encapsulation of the bacterial body. The suppurative granuloma of the skin and subcutaneous tissue with fistulas shows typical granules. There is infiltration of neutrophils and other inflammatory cells around the granules.

　　It can gradually spread and destroy adjacent muscles, tendons, fascia, and bones over several months or even years, without systemic spread or signs and symptoms suggesting systemic infection. Ultimately, the muscles become emaciated, deformed, and tissue destruction occurs, rendering the affected limb unusable. In the late stage of infection, the affected limb shows deformation and swelling, forming rod-like cystic masses, accompanied by multiple interconnected drainage sinuses and fistulas, discharging thick or serum-like exudate containing characteristic particles.

　　This disease is more common in middle-aged people, with more males than females, and is more prevalent in exposed areas of the limbs, especially the hands and feet. The course is chronic, with a history of trauma, and the skin lesions begin as dark red papules, nodules, pustules, which gradually fuse into masses and multiple abscesses, adhering to the skin, with a dark red surface. After the abscess breaks, fistulas are formed, and the fistula drainage fluid is purulent and bloody. When the subcutaneous tissue is destroyed, a greasy fluid is exuded. The drainage contains particles, which may be yellow, white, black, and other colors depending on the pathogenic bacteria, with diameters of approximately 0.3-4μm. Over time, some old skin lesions form scars, and new nodules keep appearing, forming nodules, masses, fistulas, and scars that are all over the affected limbs. The abscess invades adjacent structures including muscles, tendons, fascia, and bones, causing periostitis, osteomyelitis, and bone necrosis, leading to severe deformities and disabilities.
　　The disease progresses slowly, generally does not affect the whole body, but some pathogenic bacteria can spread through the lymphatic and blood systems, affecting internal organs.

　　Since this disease is often caused by the invasion of pathogenic bacteria through skin damage during field work, it is necessary to enhance self-protection awareness, avoid外伤 and contact with decayed matter as much as possible. In case of injury, it should be debrided in a timely manner. First, the wound surface can be cleaned with 3% hydrogen peroxide, and then iodophor can be applied for disinfection. For smaller lesions, treatment should be started as soon as possible to avoid further infection.

       1. After rinsing the particles with physiological saline, place them on a slide, add one drop of 20% sodium hydroxide, and under the microscope, the mass can be seen to be composed of intertwined hyphae and spores. The hyphae are wide and segmented, with a diameter of about 2-5μm. The ends of the hyphae and the periphery of the particles have many swollen cells. Thick-walled spores can be seen in some particles. If there are no wide hyphae, it may be caused by actinomycetes.

　　2. Culture: Cultivate on Sabouraud agar containing antibiotics, and then identify the species. Due to different treatments and prognoses, it is very important to differentiate the species.

　　3. Imaging examination: When bones are involved, X-rays can show bone necrosis, osteoporosis, and fusion of small bones, with localized osteohypertrophy and bone resorption. In cases of lung infection, it can manifest as extensive infiltrative shadows.

　　4. Histopathology: The skin and subcutaneous tissue have suppurative granuloma with fistulae, showing typical granules with infiltration of neutrophils and other inflammatory cells around them. In a few cases, degenerative myositis, lymphangitis, periostitis, bone resorption, and bone fibrosis may also be present.

　　Appropriately increase a small amount of lean meat and other protein-rich foods. Dishes should avoid being too salty, and steaming should be the main method, not fried or stir-fried. Avoid excessive drinking, overeating, drinking alcohol, and high-fat, spicy, and刺激性 food. Pay attention to light and tasty food. Fresh vegetables such as green vegetables, cabbage, radish, carrots, tomatoes, etc., can provide various vitamins and inorganic salts, which are beneficial to the repair of the body's metabolic function.

　　1. Treatment

　　For early localized lesions, local lesion excision can be adopted. If the lesion is deep in the tissue, the excision range should be wide to avoid leaving sequelae. Depending on the pathogen, sensitive drugs are selected. Amphotericin B is effective for this disease, and local lesions can be treated with a solution containing 1-2mg of amphotericin B per milliliter for local blockage. If it is a systemic infection, intravenous infusion of amphotericin B can be used. Fungal foot abscesses can also be treated with itraconazole and fluconazole, with a course of at least 3 months; for foot abscesses caused by actinomycetes and Nocardia, antibiotic or sulfonamide drugs can be used.

　　Preventing skin injuries, avoiding infection, early diagnosis, and early treatment are important measures for prevention and guaranteeing cure.

　　2. Prognosis

　　Abscess invasion of adjacent structures including muscles, tendons, fascia, and bones causes periostitis, osteomyelitis, and bone necrosis, leading to severe deformities and disabilities.