Microascus manginii is a filamentous fungal species in the genus Microascus.^[1] It produces both sexual (teleomorph) and asexual (anamorph) reproductive stages known as M. manginii and Scopulariopsis candida, respectively.^[1] Several synonyms appear in the literature because of taxonomic revisions and re-isolation of the species by different researchers.^[2] M. manginii is saprotrophic and commonly inhabits soil, indoor environments and decaying plant material.^[3] It is distinguishable from closely related species by its light colored and heart-shaped ascospores used for sexual reproduction.^[4] Scopulariopsis candida has been identified as the cause of some invasive infections, often in immunocompromised hosts, but is not considered a common human pathogen.^[5][6][7] There is concern about amphotericin B resistance in S. candida.^[6]

The anamorph was first documented, unintentionally, by Professor Fernand-Pierre-Joseph Guéguen in 1899^[8] who mistook it for the species, Monilia candida, previously described in 1851 by Hermann Friedrich Bonorden.^[9] In 1911, Jean Paul Vuillemin determined that the two taxa were distinct, noting that the taxon described by Bonorden was a yeast whereas the strain that was the subject of Guéguen's studies was filamentous and produced true conidia.^[9] Vuillemin formally described the latter as S. candida.^[9] At the same time, he re-described Bonordeon's yeast taxon, Monilia candida, as Monilia bonordenii.^[9] Subsequent researchers described taxa that have since been reduced to synonymy with S. candida, including: S. alboflavescens in 1934, S. brevicaulis var. glabra in 1949, Chrysosporium keratinophilum var. denticola in 1969 and Basipetospora denticola in 1971.^[10]

The teleomorph was discovered by Auguste Loubière in 1923 and named Nephrospora manginii in honour of his mentor, Professor Louis Mangin.^[11] It was later transferred to the genus Microascus by Mario Curzi in 1931.^[10][2] Curzi did not provide an explanation for this transfer.^[1] S. candida and M. manginii are used in the literature to describe the same species.^[2] However, recent changes to the International Code of Nomenclature for algae, fungi and plants have terminated the use of dual nomenclature for fungal species with multiple forms.^[12] It is not yet known which name will take priority for this fungus in the future.^[12]

The optimal growth temperature range for S. candida is 24–30 °C (75–86 °F), with a minimum of 5 °C and maximum 37 °C.^[3] It is a keratinophilic species which may contribute to its role in nail infections.^[16] It grows well on protein-rich surfaces and is able to digest α-keratins.^[16] In vitro study of antifungal susceptibilities reports S. candida as relatively more resistant to the antifungal drug amphotericin B, and susceptible to Itraconazole and miconazole.^[6]

M. manginii is a saprobic fungus.^[17] It has a worldwide distribution.^[17] It is often isolated from decaying plant material, soil and indoor environments, but also human skin and nails, dust, chicken litter, atmosphere, book paper and cheese, among other locations.^[3] Contaminated dust, soil and air samples are often found in North America and Europe.^[10] In Portugal, S. candida was identified as the most prevalent fungal species contaminating the air of three poultry slaughterhouses in 2016.^[18] Contamination with fungal pathogens was found on equipment used in physiotherapy clinics in Brazil, specifically electrodes and ultrasound transducers,^[19] S. candida was found on several contact electrodes.^[19]

Invasive fungal infections are becoming increasingly common in patients who are immunocompromised.^[5] M. manginii and S. candida are not traditionally recognized as common human pathogens.^[20] However, they were identified as opportunistic human and plant pathogens in a few reported cases.^[21] Other Scopulariopsis species have been associated with nail infection and keratitis (S. brevicaulis), and brain abscess and hypersensitivity pneumonitis (S. brumptii).^[6]

A case of disseminated infection caused by Scopulariopsis species in a 17-year old patient with chronic myelogenous leukemia was described in 1987.^[5] After receiving an allogenic bone marrow transplantation for cancer treatment, the patient complained of recurrent fever, nosebleeds, and abnormal sensations of the nose.^[5] Amphotericin B therapy was administered but symptoms persisted.^[5] Within two months of transplant, the patient experienced a short period of improvement followed by rapid deterioration and death.^[5] The autopsy discovered Scopulariopsis species in the lungs, blood, brain and nasal septum, and exhibited high resistance to amphotericin B in vitro.^[5] In 1989, the species responsible for the disseminated infection was identified as S. candida.^[7]

S. candida was identified as the cause of invasive sinusitis in a 12-year old girl undergoing treatment for non-Hodgkin's lymphoma in 1992.^[6] This is the second reported case of invasive sinus disease caused by Scopulariopsis species and only reported case due to S. candida.^[6] The patient was immunocompromised at the time of fungal infection due to ongoing cancer treatment.^[6] The clinical presentation resembled an infection by fungi in the order Mucorales, and involved myalgia, cheek swelling and tenderness, a week-long fever, and extensive necrosis of maxillary sinuses.^[6] As a result, the presumed diagnosis was mucormycosis until further examination of patient specimens showed abundant growth of a powdery, tan mold that was distinguished as S. candida by several features (e.g., septate hyphae, round and smooth conidia, broom-shaped conidiophores).^[6] The patient immediately received surgical drainage and debridement of damaged tissue, and amphotericin B to treat the fungal infection.^[6] Subsequent identification of S. candida as the cause of disease prompted administration of additional antifungal medication, Itraconazole, to address potential amphotericin B resistance.^[6] The patient was cured of invasive sinusitis with no signs of progressive sinus disease.^[6] This marked the first successful treatment of an invasive infection caused by Scopulariopsis species in an immunocompromised host.^[6] Immunosuppression was suspected to play a role in the ability of S. candida to cause invasive infection.^[6] The most significant contributor to managing the disease was likely strengthening the patient's immune system by suspending chemotherapy and administrating granulocyte colony-stimulating factor.^[6]

S. candida and M. manginii have been identified in cases of onychomycoses.^[2] They mainly cause tissue damage to the big toe and rarely other nails.^[16] Common symptoms include difficulty walking while wearing shoes, thickening and discolouration of nails, and deformation of nails.^[15] The infection often begins at the lateral edge of the nail instead of the proximal edge.^[16] Patients are typically middle-aged or older.^[15] The mechanism of these infections is not well-characterized.^[15] In addition, the published cases of onychomycoses caused by these species are not all reliable.^[16]