Malassezia 967636 221001479 2008-06-22T16:30:24Z Ka Faraq Gatri 6892069 Category:Agaricomycotina {{Taxobox | name = ''Malassezia'' | image = Malassezia_furfur_in_skin_scale_from_a_patient_with_tinea_versicolor_PHIL_3938_lores.jpg | image_width = 320px | image_caption = ''Malassezia furfur'' in skin scale from a patient with tinea versicolor | regnum = [[Fungus|Fungi]] | divisio = [[Basidiomycota]] | subdivisio = [[Agaricomycotina]] | classis = [[Heterobasidiomycetes]] | ordo = [[Tremellales]] | family = [[Filobasidiaceae]] | genus = '''''Malassezia''''' | subdivision_ranks = Species | subdivision = See text. }} '''''Malassezia''''' (formerly known as ''Pityrosporum'') is a genus of related [[fungi]], classified as [[yeast]]s, naturally found on the skin surfaces of many animals including humans. It can cause hypopigmentation on the chest or back if it becomes an opportunistic infection. ==Changes in nomenclature== Some confusion exists about the naming and classification of ''Malassezia'' yeast species due to a series of changes in their nomenclature. ''Malassezia'' were originally identified by the French scientist [[Louis-Charles Malassez]] in the late 19th century, hence their proper current name. In the mid 20th century they were reclassified into two species: ''Pityrosporum ovale'' which is [[lipid]] dependent and found only on humans, and ''Pityrosporum pachydermatis'', which is lipophilic but not lipid dependent and found on the skin of most animals. ''P. ovale'' was later divided into two classes, ''P. ovale'' and ''P. orbiculare'', and later renamed again as ''Malassezia furfur''. Work on these yeasts was complicated because they are extremely difficult to propagate in laboratory culture. Later, in the mid 1990s, scientists at the [[Pasteur Institute]] in Paris, France (Evelyn Gueho and Jacques Guillot) discovered that there were indeed multiple species and reclassified and named the genus as ''Malassezia'' with several distinct species. Currently there are 10 recognized species: ''M. globosa'', ''M. restricta'', ''M. furfur'', ''M. slooffiae'', ''M. symposialis'', ''M. nana'', ''M. yamatoensis'', ''M. dermatis'', ''M. obtusa'', and ''M. pachydermatis''. ==Role in human diseases== Recently, identification of ''Malassezia'' on skin has been aided by the application of molecular or DNA based techniques very similar to those used by forensic scientists to identify criminal suspects. These investigations show that in humans the species causing most skin disease, including the most common cause of [[dandruff]] and [[seborrhoeic dermatitis]] is ''M. globosa''. The skin rash of [[tinea versicolor]] (pityriasis versicolor) is also due to infection by this fungus. As the fungus requires [[fat]] to grow, it is most common in areas with many [[sebaceous gland]]s: on the scalp,<ref name=''Hawkes07''>'''Hawkes,N.''' 2007. ''Exposed - the fungus that is the real cause of dandruff.'' ''The Times'' 6 November 2007 p.14</ref> 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, about 1/300th the size of the human genome. ''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. Another surprising finding is ''M. globosa'''s ability to reproduce sexually, though this has not been seen in the laboratory or elsewhere. ==Numbers== The number of specimens of ''M. globosa'' on a human head can be up to ten million. ==Treatment of symptomatic scalp infections== Symptomatic scalp infections are often treated with [[selenium sulfide]]-containing shampoos. <Ref>[http://dermnetnz.org/treatments/selenium.html] Accessed Dec 24, 2007. </ref> ==References== <div class="references-small"> {{reflist}} * {{cite journal |author=Ashbee H, Evans E |title=Immunology of diseases associated with Malassezia species |journal=Clin Microbiol Rev |volume=15 |issue=1 |pages=21–57 |year=2002 |pmid=11781265 |url=http://cmr.asm.org/cgi/content/full/15/1/21?view=long&pmid=11781265 |doi=10.1128/CMR.15.1.21-57.2002}} * {{cite journal |author=Batra R, Boekhout T, Guého E, Cabañes F, Dawson T, Gupta A |title=Malassezia Baillon, emerging clinical yeasts |journal=FEMS Yeast Res |volume=5 |issue=12 |pages=1101–13 |year=2005 |pmid=16084129 |doi=10.1016/j.femsyr.2005.05.006}} * {{cite journal |author=Gemmer C, DeAngelis Y, Theelen B, Boekhout T, Dawson Jr T |title=Fast, noninvasive method for molecular detection and differentiation of Malassezia yeast species on human skin and application of the method to dandruff microbiology |journal=J Clin Microbiol |volume=40 |issue=9 |pages=3350–7 |year=2002 |pmid=12202578 |url=http://jcm.asm.org/cgi/content/full/40/9/3350?view=long&pmid=12202578 |doi=10.1128/JCM.40.9.3350-3357.2002}} * {{cite journal |author=Guého E, Midgley G, Guillot J |title=The genus Malassezia with description of four new species |journal=Antonie Van Leeuwenhoek |volume=69 |issue=4 |pages=337–55 |year=1996 |pmid=8836432 |doi=10.1007/BF00399623}} * {{cite journal |author=Gupta A, Batra R, Bluhm R, Boekhout T, Dawson T |title=Skin diseases associated with Malassezia species |journal=J Am Acad Dermatol |volume=51 |issue=5 |pages=785–98 |year=2004 |pmid=15523360 |doi=10.1016/j.jaad.2003.12.034}} * {{cite journal |author=Gupta A, Kohli Y, Faergemann J, Summerbell R |title=Epidemiology of Malassezia yeasts associated with pityriasis versicolor in Ontario, Canada |journal=Med Mycol |volume=39 |issue=2 |pages=199–206 |year=2001 |pmid=11346269 |doi=10.1080/714031017}} * {{cite journal |author=Gupta A, Kohli Y, Summerbell R, Faergemann J |title=Quantitative culture of Malassezia species from different body sites of individuals with or without dermatoses |journal=Med Mycol |volume=39 |issue=3 |pages=243–51 |year=2001 |pmid=11446527 |doi=10.1080/714031025}} * {{cite journal |author=Nakabayashi A, Sei Y, Guillot J |title=Identification of Malassezia species isolated from patients with seborrhoeic dermatitis, atopic dermatitis, pityriasis versicolor and normal subjects |journal=Med Mycol |volume=38 |issue=5 |pages=337–41 |year=2000 |pmid=11092380 |doi=10.1080/714030958}} * {{cite journal |author=Nell A, James S, Bond C, Hunt B, Herrtage M |title=Identification and distribution of a novel Malassezia species yeast on normal equine skin |journal=Vet Rec |volume=150 |issue=13 |pages=395–8 |year=2002 |pmid=11999275}} * {{cite journal |author=Sugita T, Takashima M, Shinoda T, Suto H, Unno T, Tsuboi R, Ogawa H, Nishikawa A |title=New yeast species, Malassezia dermatis, isolated from patients with atopic dermatitis |journal=J Clin Microbiol |volume=40 |issue=4 |pages=1363–7 |year=2002 |pmid=11923357 |url=http://jcm.asm.org/cgi/content/full/40/4/1363?view=long&pmid=11923357 |doi=10.1128/JCM.40.4.1363-1367.2002}} </div> ==External links== * [http://www.sums.ac.ir/~ijms/29_1/08-Shams.pdf IJMS Vol 29 No. 4 March 2004] * [http://www.aafp.org/afp/980700ap/noble.html aafp Diagnosis and Management of Common Tinea Infections July 1998] * Hawkes, N. 2007. ''The Times'' November 6 2007 p.14. http://news.bbc.co.uk/2/hi/health/7080434.stm [[Category:Agaricomycotina]] [[Category:Parasitic fungi]] [[Category:Yeasts]] [[de:Malassezia furfur]] [[es:Malassezia furfur]] [[sv:Malassezia]]