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Guide
Mucormycosis, formerly known as zygomycosis, is a class of conditionally pathogenic fungal diseases caused by mucormycosis fungi, which mainly affects people with low immune function, can cause various types of infections, and has the characteristics of acute onset, rapid progression and high mortality rate. Key to the treatment of mucormycosis is early aggressive surgical debridement and high-dose intravenous antifungal therapy.
Epidemiology and risk factors
Mucormycosis is an invasive fungal disease caused by a variety of fungal infections, including Rhizome, Trichophyllum, Forola, and Spp., which were previously the most common. The incidence of mucormycosis is also increasing due to the increase in the proportion of people in immunosuppressive states due to cancer and the increase in the lifespan of transplant patients and the increasing indications for the use of immunosuppressive drugs for various autoimmune diseases.
The main route of infection of mucormycosis is airborne spore inhalation, and other routes include direct ingestion and skin contact. Key risk factors include diabetes, chemical or immunotherapy oncology, solid organ and hematopoietic stem cell transplantation (HSCT), burns, cirrhosis and AIDS, and granulocytopenia. Dialysis patients with diabetic ketoacidosis and treatment with the iron chelating agent deferoxamine are also more susceptible to mucormycosis.
Clinical manifestations
The sites of infection of mucormycosis include the lungs, central nervous system, paranasal sinuses, gastrointestinal tract, and skin. Clinical manifestations are diverse and largely dependent on the route of infection and susceptibility to the disease. The main symptoms of the nasostorhinitis type are concentrated on the head and face, and the infection can begin with nasal congestion or runny nose, and then develop into facial paralysis, blurred vision, eye pain, diplopia, fever, headache, etc. Cardiopulmonary symptoms are mainly concentrated in the chest, mainly manifested as fever, cough and sputum, chest pain, hemoptysis and dyspnea. Patients with cutaneous mucormycosis often have skin lesions such as trauma and burns, which can manifest as skin plaque, swelling and necrosis. Gastrointestinal type is rare, more common in severe malnutrition and gastrointestinal dysfunction, often with abdominal pain, vomiting, diarrhea, blood in the stool and so on. Disseminated mucormycosis may originate at the primary site of any infection, primarily an infection in two or more organs.
Diagnostic assessment
Routine haematological tests for mucormycosis are rarely diagnostic, but the presence of neutropenia is a relevant risk factor.
Imaging is important for the evaluation of disease and may examine areas of suspected mucormycosis, particularly the brain, paranasal sinuses, lungs, and abdomen. Given the rapid progression of mucormycosis, ct scans are recommended once a week, especially in patients who are unstable. CT scan of nasocerebral mucormycosis helps to assess adjacent structures such as the eye and brain, ct presents with soft tissue oedema of the cavity mucosa, thickening of the mucosal membrane of the sinuses, bone erosion, and orbital invasion. In immunosuppressed patients with respiratory symptoms, a chest ct should be performed. Patients with gastrointestinal type require CT to assess the status of enteritis.
The gold standard for the diagnosis of mucormycete infection is tissue, sterile humor culture, or histopathological biopsy; the characteristics of the staining of the mucormyces smear are: the hyphae are wide-banded and undivided, the diameter may be large or small, but the branches are at right angles. Clinical specimens of suspected mucormycosis, direct microscopic examination with fluorescent staining is preferred. Histopathological sections he, pas or silver staining, see clear hyphae, width 6 to 16 μm, maximum width of 25 μm, no septum or less septum, may be vertical and irregular branching.
treat
Standard management measures for mucormycosis include early diagnosis, reversal of risk factors and underlying disease, surgical debridement, and timely intravenous administration of antifungal drugs, usually amphotericinb. Prompt management of hyperglycemia, acidosis, and cessation of immunosuppressants as much as possible are required.
Amphotericin b liposomes were significantly reduced compared with amphotericin b adverse reactions, which is a first-line drug for mucormycete infection. The initial dose is 5 mg/kg/d iv and the maximum dose is 5 mg/kg/day. The duration of treatment depends mainly on the patient's clinical condition. To prevent renal failure, posaconazole or isaconazole is an option. Isaconazole is as effective as amphotericin b preparations and has been licensed for first-line treatment of mucormycosis in the United States.
If amphotericinb liposome intolerance, the dose can be reduced, but should be maintained ≥ 5 mg/kg/day. If the disease is generalized, rapidly progressing, or the patient's general condition is poor, the addition of isaconazole or posaconazole may be considered. Treatment should be continued until imaging is completely improved and until the host immunity is completely reconstituted, and isaconazole or posaconazole may be used as maintenance-phase therapy.
In addition to systemic antifungal therapy, surgical debridement of the infection as well as necrotic tissue should be performed urgently to limit the further spread of infection. Depending on the site of infection, the surgeries involved may include radical facial resection, partial pneumonectomy, colectomy, etc. Other adjunctive treatments include hyperbaric oxygen therapy, where increasing oxygen pressure promotes wound healing.
Resources:
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4. Chen Songsheng, He Ya. Mucormycosis: a serious infection[j].Medicine and Health Care,2012,20(01):12-13.