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Aspergillosis and Mucormycosis
Published in Rebecca A. Cox, Immunology of the Fungal Diseases, 2020
Alayn R. Waldorf, Richard D. Diamond
Several studies have investigated the ability of numerous genera, species, and strains of the Mucorales to cause infection in normal, cortisone-treated, and alloxan-induced diabetic animals.53,54,151,152 In diabetic animals, Rhizopus is consistently more pathogenic than Absidia or Rhizomucor.53,54 Thermotolerant isolates of Rhizopus oryzae produce an alkaline proteinase with proteolytic activity within the normal physiological pH range. Its role in pathogenesis is unknown at this time.
Epidemiology of fungal infections: What, where, and when
Published in Mahmoud A. Ghannoum, John R. Perfect, Antifungal Therapy, 2019
Frederic Lamoth, Sylvia F. Costa, Barbara D. Alexander
The agents of mucormycosis are members either of the order Entomophthorales or of the order Mucorales. These organisms are characterized by sparsely septate hyphae in tissue. The hyphae are broad, variable in diameter, and polymorphic, with irregular branching, and in the case of the Mucorales, may invade blood vessels with thrombosis, tissue infarction, and necrosis [5,70,215,273]. The molds of the order Entomophthorales are usually found in tropical areas, in soil, decaying vegetation, on insects, and as saprobes in the gastrointestinal tract of reptiles, amphibians, and mammals. Of the Entomophthorales, Basidiobolus and Conidiobolus species are pathogenic to humans, causing subcutaneous infections of the extremities and trunk, and of the nasal submucosa, respectively [274]. Members of the order Mucorales are found in soil, decaying vegetation, fruits, foodstuffs, and animal excreta in a wide geographic distribution. The portal of entry for infection is likely pulmonary with eventual dissemination to other sites, though primary cutaneous infection has been reported [275]. The Mucorales cause the majority of cases of human mucormycosis, with Rhizopus, Mucor, Rhizomucor, Lichtheimia (formerly Absidia), Apophysomyces, and Cunninghamella, among others, found in the literature [47,274,276–279]. The most commonly reported cause of human infection is Rhizopus.
Mucor and Mucormycosis
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
The family Rhizopodaceae includes (1) a thermotolerant Rhizopus microsporus clade (R. microsporus, R. caespitosus, R. homothallicus, and R. schipperae, growing at up to 45°C); (2) a sub-thermotolerant R. arrhizus group (growing at 37°C–40°C); and (3) a mesophilic group (R. stolonifer, Sporodiniella, and Syzygites). Although several members of the genus Rhizopus are infective to humans (e.g., Rhizopus oryzae [synonyms: Rhizopus arrhizus, Rhizopus arrhizus var. arrhizus], Rhizopus microsporus var. rhizopodiformis), R. oryzae predominates human mucormycosis cases. Occurring in soil, on decaying fruits, on dung, and on moist fresh organic matter in contact with soil, Rhizopus may be occasionally involved in spoilage of bread and other food, and thus is called “black bread mold” or “pin-head mold” (a name shared with Mucor) [4].
Advances in the diagnosis of fungal pneumonias
Published in Expert Review of Respiratory Medicine, 2020
Bryan T. Kelly, Kelly M. Pennington, Andrew H. Limper
Mucormycosis refers to infection caused by fungi of the class Zygomycetes, which contains the order Mucorales. A recent systemic review and meta-analysis of case reports found that the most common species causing infection are those of the Rhizopus genus (48%) followed by Mucor(14%), Lichtheimia(13%), Apophysomyces(8%), Cunninghamella(7%), Rhizomucor (6%), and Saksenaea(3%), though it is important to note that epidemiology varies by infected patient population and organ system involved [21]. Mucormycosis continues to be observed with increasing frequency in clinical practice. Hematologic malignancies, hematopoietic stem cell and solid organ transplant, poorly controlled diabetes, prolonged corticosteroid use, antifungal prophylaxis with voriconazole, and iron overload and chelation therapy with deferoxamine have been associated with an increased risk of invasive Mucormycosis [22]. Rhino-orbital-cerebral infections represent the most common site of infection (34%) followed by skin (22%) and pulmonary (20%) [21]. Among risk factors, solid organ transplant and neutropenia are particularly associated with pulmonary Mucormycosis which carries a 51% mortality rate [21].
Evolution of antifungals for invasive mold infections in immunocompromised hosts, then and now
Published in Expert Review of Anti-infective Therapy, 2023
Zoe Freeman Weiss, Jessica Little, Sarah Hammond
Mucormycosis is most common in patients with impaired cell-mediated immunity, such as those with hematological malignancies, neutropenia, and bone marrow or organ transplantation. Patients with diabetic ketoacidosis may be prone to infection with Rhizopus spp, due to the presence of fungal ketone reductase, favoring growth in high glucose acidic conditions [129]. Mucormycosis is also associated with natural disasters (due to increased environmental exposures) and combat-related traumatic wounds in immunocompetent hosts [130]. Recently, mucormycosis has been identified in patients with COVID-19 with underlying diabetes and steroid use [131]. Mucormycosis is less common than aspergillosis and accounts for up to 10% of molds isolated from patients with SOT or HSCT [132–134].
Mucormycosis experience through the eyes of the laboratory
Published in Infectious Diseases, 2019
Pınar Sağıroğlu, Ayşe Nedret Koç, Mustafa Altay Atalay, Gülşen Altinkanat Gelmez, Özlem Canöz, Fatma Mutlu Sarıgüzel
Rhizopus spp. or Mucorales spp. identification was performed according to microscopic and macroscopic examination. Microscopic morphology showed typically ribbon-like, irregularly shaped, non-septate or sparsely septated hyphae, broad (diameter, 6–16 μm) hyphae with right angles branching in the samples. In culture plates, moulds quickly fill the agar surface and demonstrated greyish-white, cotton candy-like texture colonies on Sabouraud’s dextrose agar medium except for Sabouraud’s dextrose agar with cycloheximide medium. The slide culture on potato dextrose agar showed broad hyphae without septa, the presence of hyaline stolons, brown pigmented rootlike hyphae (rhizoids) and sporangiophores that were long and terminated with a dark, round sporangium.