Biology:Malassezia

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Malassezia
Malassezia furfur in skin scale from a patient with tinea versicolor PHIL 3938 lores.jpg
Malassezia furfur in skin scale from a patient with tinea versicolor
Scientific classification
Kingdom:
Fungi
Division:
Class:
Exobasidiomycetes
Order:
Malasseziales
Family:
Malasseziaceae
Genus:
Malassezia

Malassezia (formerly known as Pityrosporum) is a genus of fungi. Malassezia is naturally found on the skin surfaces of many animals, including humans. In occasional opportunistic infections, some species can cause hypopigmentation or hyperpigmentation on the trunk and other locations in humans. Allergy tests for this fungus are available.

Nomenclature

A 25-year-old man with pityrosporum folliculitis and electron micrograph of his skin, showing Malassezia spores.[1]

Due to progressive changes in their nomenclature, some confusion exists about the naming and classification of Malassezia yeast species. Work on these yeasts has been complicated because they require specific growth media and grow very slowly in laboratory culture.

Malassezia were originally identified by the French scientist Louis-Charles Malassez in the late 19th century. Raymond Sabouraud identified a dandruff-causing organism in 1904 and called it "Pityrosporum malassez", honoring Malassez, but at the species level as opposed to the genus level. When it was determined that the organisms were the same, the term "Malassezia" was judged to possess priority.[2]

In the mid-20th century, it was reclassified into two species:

  • Pityrosporum (Malassezia) ovale, which is lipid-dependent and found only on humans. P. ovale was later divided into two species, P. ovale and P. orbiculare, but current sources consider these terms to refer to a single species of fungus, with M. furfur the preferred name.[3]
  • Pityrosporum (Malassezia) pachydermatis, which is lipophilic but not lipid-dependent. It is found on the skin of most animals.

In the mid-1990s, scientists at the Pasteur Institute in Paris, France, discovered additional species.[4]

Currently there are at least 17 recognized species:

...

Role in human diseases

Identification of Malassezia on skin has been aided by the application of molecular or DNA-based techniques. These investigations show that the Malassezia species causing most skin disease in humans, including the most common cause of dandruff and seborrhoeic dermatitis, is M. globosa (though M. restricta is also involved).[8] The skin rash of tinea versicolor (pityriasis versicolor) is also due to infection by this fungus.

As the fungus requires fat to grow,[4] it is most common in areas with many sebaceous glands: on the scalp,[17] face, and upper part of the body. When the fungus grows too rapidly, the natural renewal of cells is disturbed, and dandruff appears with itching (a similar process may also occur with other fungi or bacteria).

A project in 2007 has sequenced the genome of dandruff-causing Malassezia globosa and found it to have 4,285 genes.[18] M. globosa uses eight different types of lipase, along with three phospholipases, to break down the oils on the scalp. Any of these 11 proteins would be a suitable target for dandruff medications.

M. globosa has been predicted to have the ability to reproduce sexually,[19] but this has not been observed.

The fungus appears to play a role in the development of some pancreatic cancers, as a result of it migrating from the gut lumen to the pancreas.[20]

The number of specimens of M. globosa on a human head can be up to ten million.[17]

Treatment of symptomatic scalp infections

Symptomatic scalp infections are often treated with selenium disulfide,[21] zinc pyrithione, or ketoconazole containing shampoos.

There are several natural antifungal remedies for seborrhoeic dermatitis including garlic, onions, coconut oil, apple cider vinegar, Tea tree oil (Melaleuca alternifolia oil), honey, and cinnamic acid.[22][23][24] The efficacy of these natural treatments can vary considerably between individuals.

References

  1. Ran Yuping (2016). "Observation of Fungi, Bacteria, and Parasites in Clinical Skin Samples Using Scanning Electron Microscopy". in Janecek, Milos. Modern Electron Microscopy in Physical and Life Sciences. InTech. doi:10.5772/61850. ISBN 978-953-51-2252-4. 
  2. "The genus Malassezia and human disease". Indian J Dermatol Venereol Leprol 69 (4): 265–70. 2003. PMID 17642908. http://www.ijdvl.com/article.asp?issn=0378-6323;year=2003;volume=69;issue=4;spage=265;epage=270;aulast=Inamadar. 
  3. Template:Fitzpatrick 6
  4. 4.0 4.1 "The genus Malassezia with description of four new species". Antonie van Leeuwenhoek 69 (4): 337–55. May 1996. doi:10.1007/BF00399623. PMID 8836432. 
  5. 5.0 5.1 "Two new lipid-dependent Malassezia species from domestic animals". FEMS Yeast Research 7 (6): 1064–1076. 2007. doi:10.1111/j.1567-1364.2007.00217.x. ISSN 1567-1356. PMID 17367513. 
  6. "Malassezia cuniculi sp. nov., a novel yeast species isolated from rabbit skin". Medical Mycology 49 (1): 40–48. 2011. doi:10.3109/13693786.2010.493562. PMID 20560865. 
  7. "New Yeast Species, Malassezia dermatis, Isolated from Patients with Atopic Dermatitis". J. Clin. Microbiol. 40 (4): 1363–7. April 2002. doi:10.1128/JCM.40.4.1363-1367.2002. PMID 11923357. 
  8. 8.0 8.1 "Isolation and expression of a Malassezia globosa lipase gene, LIP1". J. Invest. Dermatol. 127 (9): 2138–46. September 2007. doi:10.1038/sj.jid.5700844. PMID 17460728. 
  9. Sugita, Takashi; Masako Takashima; Minako Kodama; Ryoji Tsuboi; Akemi Nishikawa (October 2003). "Description of a New Yeast Species, Malassezia japonica, and Its Detection in Patients with Atopic Dermatitis and Healthy Subjects". J. Clin. Microbiol. 41 (10): 4695–4699. doi:10.1128/JCM.41.10.4695-4699.2003. PMID 14532205. 
  10. "Malassezia nana sp. nov., a novel lipid-dependent yeast species isolated from animals". Int. J. Syst. Evol. Microbiol. 54 (Pt 2): 623–7. March 2004. doi:10.1099/ijs.0.02776-0. PMID 15023986. 
  11. "Biotyping of Malassezia pachydermatis strains using the killer system". Rev Iberoam Micol 15 (2): 85–7. June 1998. PMID 17655416. 
  12. "Genotype analysis of Malassezia restricta as the major cutaneous flora in patients with atopic dermatitis and healthy subjects". Microbiol. Immunol. 48 (10): 755–9. 2004. doi:10.1111/j.1348-0421.2004.tb03601.x. PMID 15502408. 
  13. "Malassezia slooffiae-associated dermatitis in a goat". Vet. Dermatol. 18 (5): 348–52. October 2007. doi:10.1111/j.1365-3164.2007.00606.x. PMID 17845623. 
  14. "Is common neonatal cephalic pustulosis (neonatal acne) triggered by Malassezia sympodialis?". Arch Dermatol 134 (8): 995–8. August 1998. doi:10.1001/archderm.134.8.995. PMID 9722730. 
  15. "A new yeast, Malassezia yamatoensis, isolated from a patient with seborrheic dermatitis, and its distribution in patients and healthy subjects". Microbiol. Immunol. 48 (8): 579–83. 2004. doi:10.1111/j.1348-0421.2004.tb03554.x. PMID 15322337. 
  16. "Malassezia vespertilionis sp. nov. :a new cold-tolerant species of yeast isolated from bats". Persoonia 41: 56–70. 2018. doi:10.3767/persoonia.2018.41.04. PMID 30728599. PMC 6344816. http://www.repository.naturalis.nl/document/654583. 
  17. 17.0 17.1 "Genetic code of dandruff cracked". BBC News. 6 November 2007. http://news.bbc.co.uk/2/hi/health/7080434.stm. Retrieved 2008-12-10. 
  18. "Dandruff-associated Malassezia genomes reveal convergent and divergent virulence traits shared with plant and human fungal pathogens". Proc. Natl. Acad. Sci. U.S.A. 104 (47): 18730–5. November 2007. doi:10.1073/pnas.0706756104. PMID 18000048. Bibcode2007PNAS..10418730X. 
  19. "The genus Malassezia: old facts and new concepts". Parassitologia 50 (1–2): 77–9. June 2008. PMID 18693563. 
  20. Aykut, Berk; Pushalkar, Smruti; Chen, Ruonan; Li, Qianhao; Abengozar, Raquel; Kim, Jacqueline I.; Shadaloey, Sorin A.; Wu, Dongling et al. (October 2019). "The fungal mycobiome promotes pancreatic oncogenesis via activation of MBL". Nature 574 (7777): 264–267. doi:10.1038/s41586-019-1608-2. PMID 31578522. 
  21. DermNet treatments/selenium Retrieved Dec 24, 2007..
  22. Gupta, Aditya K; Nicol, Karyn; Batra, Roma (2004). "Role of Antifungal Agents in the Treatment of Seborrheic Dermatitis". American Journal of Clinical Dermatology 5 (6): 417–422. doi:10.2165/00128071-200405060-00006. PMID 15663338. 
  23. Al-Waili, N. S. (2001). "Therapeutic and prophylactic effects of crude honey on chronic seborrheic dermatitis and dandruff". European Journal of Medical Research 6 (7): 306–8. PMID 11485891. 
  24. Shams-Ghahfarokhi, Masoomeh; Shokoohamiri, Mohammad-Reza; Amirrajab, Nasrin; Moghadasi, Behnaz; Ghajari, Ali; Zeini, Farideh; Sadeghi, Golnar; Razzaghi-Abyaneh, Mehdi (June 2006). "In vitro antifungal activities of Allium cepa, Allium sativum and ketoconazole against some pathogenic yeasts and dermatophytes". Fitoterapia 77 (4): 321–323. doi:10.1016/j.fitote.2006.03.014. PMID 16690223. 

External links

See also Wikidata entry Q14488912.