(See also Overview of Fungal Infections Overview of Fungal Infections Fungal infections are often classified as either Opportunistic Primary Opportunistic infections are those that develop mainly in immunocompromised hosts. Primary infections can develop in immunocompetent... read more .)
Many different species of fungi can cause mucormycosis. Each species causes similar symptoms.
Mucormycosis is most common among immunocompromised people, in patients with poorly controlled diabetes (particularly those with ketoacidosis), and in patients receiving the iron-chelating drug deferoxamine.
The most common form of mucormycosis is
Rhinocerebral
However, primary cutaneous, pulmonary, or gastrointestinal lesions sometimes develop, and hematogenous dissemination to other sites can occur.
Cutaneous Rhizopus infections have developed under occlusive dressings but more often result from trauma when the injured areas are contaminated with soil containing fungal spores, as may occur in natural disasters or in combat-related blast injuries. Although cutaneous mucormycosis is often opportunistic, cutaneous infections may develop in immunocompetent hosts if trauma results in contamination with fungal spores.
Symptoms and Signs of Mucormycosis
Rhinocerebral mucormycosis is usually severe and frequently fatal unless diagnosed early and treated aggressively.
Necrotic lesions appear on the nasal mucosa or sometimes the palate. Vascular invasion by hyphae leads to thrombosis and to progressive tissue necrosis that may involve the nasal septum, palate, and bones surrounding the orbit or sinuses. Manifestations may include pain, fever, orbital cellulitis, proptosis, ophthalmoplegia, loss of vision, purulent nasal discharge, and mucosal necrosis.
Progressive extension of necrosis to the brain can cause signs of cavernous sinus thrombosis, seizures, aphasia, or hemiplegia.
Pulmonary mucormycosis resembles invasive aspergillosis. Pulmonary symptoms (eg, productive cough, high fever, dyspnea) are severe.
Diagnosis of Mucormycosis
Examination of tissue samples for broad, ribbon-like, nonseptate hyphae
Culture
Diagnosis of mucormycosis requires a high index of suspicion and painstaking examination of tissue samples for large nonseptate hyphae with irregular diameters and right-angle branching patterns; the examination must be thorough because much of the necrotic debris contains no organisms. For unclear reasons, cultures may be negative, even when hyphae are clearly visible in tissues.
CT and x-rays often underestimate or miss significant bone destruction.
Treatment of Mucormycosis
Control of underlying condition
Lipid amphotericin B formulations
Isavuconazole
Surgical debridement
(See also Antifungal Drugs Antifungal Drugs Drugs for systemic antifungal treatment include the following (see Table: Some Drugs for Systemic Fungal Infections): Amphotericin B (and its lipid formulations) Various azole derivatives (fluconazole... read more .)
Effective therapy requires that diabetes be controlled or, if at all possible, immunosuppression be reversed or deferoxamine be stopped.
A high-dose lipid amphotericin B formulation (7.5 to 10 mg/kg IV once a day) is recommended as initial therapy. Isavuconazole is approved for primary therapy. However, clinical experience with isavuconazole is relatively limited, and in severely ill patients, amphotericin B likely remains the drug of choice. Posaconazole may also be effective, especially as consolidation therapy. Posaconazole has not been studied as primary therapy.
Complete surgical debridement of necrotic tissue is critical.
