Microascus manginii

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Microascus manginii
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Microascales
Family: Microascaceae
Genus: Microascus
Species:
M. manginii
Binomial name
Microascus manginii
(Loubière) Curzi (1931)
Synonyms
  • Nephrospora manginii Loubière (1923)
  • Scopulariopsis candidaVuill. (1911)
  • Monilia candidaGuég. (1899)
  • Chrysosporium keratinophilum var. denticolaC. Moreau (1969)

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]

Contents

History and taxonomy

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]

Growth and morphology

Sexual form

Colonies of M. manginii are pale, white and rapid growing. [2] [3] Growth is tolerant of cycloheximide and restricted at 37 °C. [3] The vegetative hyphae are septate and appear glassy (hyaline). [2] [13] Ascomata are the sexual structures within which ascospores are produced in sacs called asci. [2] The ascomata of M. manginii are spherical, smooth-walled, dark-brown to black and 100–175 μm in size. [2] [13] These fruiting bodies are also called perithecia because of their flask-like shape wherein asci grow at the base and an opening allows for the release of mature ascospores. [2] [13] They are also papillate with short cone-shaped projections at the opening, sessile, and rich in carbon. [1] [13] Perithecia manifest as small black dots organized in concentric rings. [13] An incubation period of over two weeks may be necessary for the production of perithecia. [13] The asci are shaped similar to an upside-down egg where the apex is broad and thicker than the base. [2] [13] They are 11–16 × 8–13 μm in size and contain 8 ascospores. [1] [2] [13] Ascospores are nonseptate and smooth-walled. [13] [4] They are characteristically uniform in heart-shape and pale, straw-colored when mature - but appear reddish-brown as a mass. [4] They each have a single inconspicuous germ pore, which is a predetermined spot in the spore cell wall where the germ tube emerges during germination. [13] Ascospores are 5–6 × 4.5–5 μm in size. [2] [3] [13] M. manginii is a heterothallic species and as a result, generation of sexual spores requires mating between two compatible individuals. [14]

Asexual form

S. candida is a hyaline mold with septate hyphae. [3] [6] The white and membranous morphology of S. candida colonies differentiates it from the more common species S. brevicaulis, which is characterized by a sand-coloured and granular colonial morphology. [13] As the colony ages, it becomes slightly yellow. [1] Conidiophores are specialized hyphal stalks that have conidiogenous cells which produce conidia for asexual reproduction. [1] The Latin word for broom, scopula , was chosen as the basis of the generic name due to the broom-like appearance of the conidiophores of Scopulariopsis. [6] In S. candida, these structures are 10–20 μm in length. [1] S. candida sporulates using specialized conidiogenous cells called annellide. [1] The tip of the cell elongates and narrows each time a conidium is formed and results in a series of ring-like scars called annellations near the tip. [1] The annelloconidia are formed in dry chains that eventually break off to allow the dispersal of spores by wind. [15] They are one-celled, smooth- and thick-walled, and round but also broad-based. [13] [6] [10] They resemble simple yeasts. [6] Annelloconidia are hyaline and 6–8 × 5–6 μm in size. [13] [6] The smooth hyaline annelloconidia can also distinguish S. candida from S. brevicaulis, which has conidia that are rough-walled, truncate and covered in tiny, thorny outgrowths. [13] Isolates of S. candida can produce sterile perithecia-like structures. [14]

Physiology

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]

Habitat and ecology

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]

Pathogenicity

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]

References

  1. 1 2 3 4 5 6 7 8 9 10 Barron, G. L.; Cain, R. F.; Gilman, J. C. (November 1961). "The Genus Microascus". Canadian Journal of Botany. 39 (7): 1609–1631. doi:10.1139/b61-143. ISSN   0008-4026.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 MycoBank Database. "Microascus manginii". www.mycobank.org.
  3. 1 2 3 4 5 6 7 Howard, Dexter H. (2007). Pathogenic fungi in humans and animals (2nd ed.). New York, NY: Dekker. ISBN   978-0824706838.
  4. 1 2 3 "Microascus Species - Doctor Fungus". Doctor Fungus.
  5. 1 2 3 4 5 6 7 Neglia, Joseph P.; Hurd, David D.; Ferrieri, Patricia; Snover, Dale C. (December 1987). "Invasive scopulariopsis in the immunocompromised host". The American Journal of Medicine. 83 (6): 1163–1166. doi:10.1016/0002-9343(87)90961-2.
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Kriesel, J. D.; Adderson, E. E.; Gooch, W. M.; Pavia, A. T. (1 August 1994). "Invasive Sinonasal Disease Due to Scopulariopsis candida: Case Report and Review of Scopulariopsosis". Clinical Infectious Diseases. 19 (2): 317–319. doi:10.1093/clinids/19.2.317.
  7. 1 2 Anaissie, EJ; Bodey, GP; Rinaldi, MG (April 1989). "Emerging fungal pathogens". European Journal of Clinical Microbiology & Infectious Diseases. 8 (4): 323–30. doi:10.1007/bf01963467. PMID   2497012.
  8. ↑ "Scopulariopsis". www.mycobank.org.
  9. 1 2 3 4 Vuillemin, Jean Paul (1911). "Différence fondamentale entre le genre Monilia et les genres Scopulariopsis, Acmosporium et Catenularia". Bulletin de la Société Mycologique de France. 27: 137–152.
  10. 1 2 3 4 Sandoval-Denis, M.; Gené, J.; Sutton, D.A.; Cano-Lira, J.F.; de Hoog, G.S.; Decock, C.A.; Wiederhold, N.P.; Guarro, J. (30 June 2016). "Redefining Microascus, Scopulariopsis and allied genera". Persoonia. 36 (1): 1–36. doi:10.3767/003158516X688027. PMC   4988368 . PMID   27616786.
  11. ↑ Loubiere, A (July 1923). "Sur un nouveau genre de Pyrenomycetes". Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. 177: 209.
  12. 1 2 Taylor, John W.; Göker, Markus; Pitt, John I. (June 2016). "Choosing one name for pleomorphic fungi: The example of Aspergillus versus Eurotium, Neosartorya and Emericella". Taxon. 65 (3): 593–601. doi:10.12705/653.10.
  13. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 "Microascus manginii - Doctor Fungus". Doctor Fungus.
  14. 1 2 Abbott, Sean P.; Sigler, Lynne (November 2001). "Heterothallism in the Microascaceae Demonstrated by Three Species in the Scopulariopsis brevicaulis Series". Mycologia. 93 (6): 1211. doi:10.2307/3761682. JSTOR   3761682.
  15. 1 2 3 4 Liu, Dongyou; Boca, Raton (2011). Molecular detection of human fungal pathogens. CRC Press. ISBN   9781439812402.
  16. 1 2 3 4 5 Gupta, Aditya K; Ryder, Jennifer E; Baran, Robert; Summerbell, Richard C (April 2003). "Non-dermatophyte onychomycosis". Dermatologic Clinics. 21 (2): 257–268. doi:10.1016/s0733-8635(02)00086-4.
  17. 1 2 Ropars, Jeanne; Cruaud, Corinne; Lacoste, Sandrine; Dupont, Joëlle (April 2012). "A taxonomic and ecological overview of cheese fungi". International Journal of Food Microbiology. 155 (3): 199–210. doi:10.1016/j.ijfoodmicro.2012.02.005. PMID   22381457.
  18. ↑ Viegas, Carla; Faria, Tiago; dos Santos, Mateus; Carolino, Elisabete; Sabino, Raquel; Quintal Gomes, Anita; Viegas, Susana (8 March 2016). "Slaughterhouses Fungal Burden Assessment: A Contribution for the Pursuit of a Better Assessment Strategy". International Journal of Environmental Research and Public Health. 13 (3): 297. doi: 10.3390/ijerph13030297 . PMC   4808960 . PMID   27005642.
  19. 1 2 Mobin, Mitra; de Moraes Borba, Cintia; de Moura Filho, Oséas F.; de Melo Neto, Antonio Quaresma; Valenti, Vitor E.; Vanderlei, Luiz Carlos Marques; de Abreu, Luiz Carlos (December 2011). "The presence of fungi on contact electrical stimulation electrodes and ultrasound transducers in physiotherapy clinics". Physiotherapy. 97 (4): 273–277. doi:10.1016/j.physio.2010.11.010. PMID   22051582.
  20. ↑ Kordalewska, Milena; Jagielski, Tomasz; Brillowska-Dąbrowska, Anna (2 June 2016). "Rapid Assays for Specific Detection of Fungi of Scopulariopsis and Microascus Genera and Scopulariopsis brevicaulis Species". Mycopathologia. 181 (7–8): 465–474. doi:10.1007/s11046-016-0008-5. PMC   4937093 . PMID   27255522.
  21. ↑ Skóra, Magdalena; Macura, Anna B.; Bulanda, Małgorzata (October 2014). "In vitro antifungal susceptibility of Scopulariopsis brevicaulis isolates". Medical Mycology. 52 (7): 723–727. doi: 10.1093/mmy/myu039 . PMID   25049036.
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