ESSENTIALS OF DIAGNOSIS
Most common cause of non-Aspergillus invasive mold infection.
Predisposing factors: poorly controlled diabetes, leukemia, transplant recipient, wound contamination by soil.
Pulmonary, rhinocerebral, and skin are most common disease sites.
Rapidly fatal without multidisciplinary interventions.
The term “mucormycosis” is applied to opportunistic infections caused by members of the genera Rhizopus, Mucor, Lichtheimia (formerly Absidia), and Cunninghamella. Predisposing conditions include hematologic malignancy, stem cell transplantation, solid organ transplantation, diabetic ketoacidosis, chronic kidney disease, and treatment with desferoxamine, corticosteroids, or cytotoxic drugs.
Invasive disease of the sinuses, orbits, and the lungs may occur. Necrosis is common due to hyphal tissue invasion that may manifest as ulceration of the hard palate or nasal palate or hemoptysis. Widely disseminated disease can occur. No serologic or laboratory findings assist with diagnosis, and blood cultures are unhelpful. A reverse “halo sign” (focal area of ground glass diminution surrounded by a ring of consolidation) may be seen on chest CT. Biopsy of involved tissue remains the cornerstone of diagnosis, although cultures are frequently negative. The organisms appear in tissues as broad, branching nonseptate hyphae.
Optimal therapy of mucormycosis involves reversal of predisposing conditions (if possible), surgical debridement, and prompt antifungal therapy. A prolonged course of a lipid preparation of intravenous liposomal amphotericin B (5 mg/kg with higher doses possibly given for CNS disease) should be started early (Table 36–1). Depending on in vitro susceptibility, posaconazole 300 mg/day orally can be used after disease has been stabilized. Combination therapy with amphotericin and posaconazole is not proven but is commonly used because of the poor response to monotherapy. Isavuconazole has been shown to have some clinical activity for mucormycosis, but the data for life-threatening disease is still not established, and the drug probably should not be used in that particular setting. Other azoles are not effective. There are limited data suggesting beneficial synergistic activity when amphotericin and caspofungin are used in combination for rhino-orbital mucormycosis in diabetic patients. Despite favorable animal studies, a pilot study in humans incorporating adjunctive iron chelation therapy with deferasirox demonstrated a higher mortality rate than antifungal therapy alone. Control of diabetes and other underlying conditions, along with extensive repeated surgical removal of necrotic, nonperfused tissue, is essential. Even when these measures are introduced in a timely fashion, the prognosis remains guarded.
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et al. Isavuconazole treatment for mucormycosis: a single-arm open-label trial and case-control analysis. Lancet Infect Dis. 2016 Jul;16(7):828–37.
et al. Therapy of mucormycosis. J Fungi (Basel). 2018 Jul 31;4(3):E90.
et al. Challenges in the diagnosis ...