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Malassezia spp.
(described by Baillon in 1889)

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Taxonomic Classification

Kingdom: Fungi
Phylum: Basidiomycota
Class: Hymenomycetes
Order: Tremellales
Family: Filobasidiaceae
Genus: Malassezia

Description and Natural Habitats

Malassezia is a lipophilic yeast found on skin and body surfaces of humans and animals. It has been shown that colonization with Malassezia may occur as early as neonatal period [790]. It is a member of the normal skin flora in as much as 90% of adults and may occasionally cause superficial and deep mycoses. Malassezia has no known teleomorphic phase.

Species

There are seven proposed species in the genus Malassezia based on molecular, morphological, and biochemical profiles [276, 924, 948, 1361, 2077, 2395]. The most common and well-known species are Malassezia furfur and Malassezia pachydermatis [1216]. See the complete list of active species and summary of synonyms for the Malassezia spp.

Pathogenicity and Clinical Significance

Malassezia infections are mostly endogenous and originate from the colonized skin [240]. They may occur in otherwise healthy individuals as well as immunocompromised hosts, such as bone marrow transplant recipients, patients with cancer or AIDS [55, 755, 908, 1251, 1464, 1582].

The most common clinical picture caused by Malassezia furfur is pityriasis versicolor [947]. It may also cause seborrheic dermatitis [55], folliculitis [1019], neonatal pustulosis [1874], blepharitis [2250], and white piedra [1364]. Given the lipophilic nature of the fungus, fungemia, catheter-related infections and sepsis due to Malassezia furfur may occur particularly in patients who are on parenteral nutrition with lipids [129, 146, 176, 510, 1603, 2050]. Noteworthy, colonization of the catheters with Malassezia may occur in absence of lipid administration as well [298]. Malassezia globosa and Malassezia sympodialis are also common causes of pityriasis versicolor in humans [947, 1684].

Malassezia pachydermatis is a distinctive species due to its well-known zoophilic nature [417, 1859]. It causes canine otitis externa and is prevalent in carnivores. However, according to current knowledge, Malassezia pachydermatis is not the only Malassezia species associated with infections or colonization in animals [1859]. Some lipid-dependent species of Malassezia may also be isolated as occasional causes of canine otitis externa [481]. Malassezia pachydermatis may cause disseminated infections in humans as well [1294, 1533].

Macroscopic Features

Malassezia colonies grow rapidly and mature in 5 days at 30-37°C. Growth is weak when it is incubated at 25°C. The colonies are raised and smooth initially and get dry and wrinkled in time. The color of the Malassezia furfur colonies is creamy yellow to brown while those of Malassezia pachydermatis are cream-colored initially and become buff to orange beige in time [531, 1295, 2202].

One of the most important differences between Malassezia furfur and Malassezia pachydermatis is their relative lipid dependence. Malassezia furfur requires long chain fatty acids for growth. The most practical and commonly applied method to supplement the medium with these fatty acids is to overlay the medium with a thin layer of olive oil. Unlike Malassezia furfur, Malassezia pachydermatis does not require fatty acids.

Microscopic Features

Yeast-like conidia are the predominant structures. These cells are globose to ellipsoidal in shape and round at one end and blunt at the other. The blunt site is where bottle-shaped, unipolar budding occurs from the phialides with small collarettes. The width of the bud with respect to that of the mother cell may vary from one species to other. Occasionally, few rudimentary hyphal elements are also observed. Sexual spores do not exist [531, 1295, 2202].

Direct microscopic examination of the skin scrapings reveals yeast cells and hyphal fragments. This appearence resembles to and is called spaghetti and meatballs [2202].

Compare

Candidaspp.

Laboratory Precautions

No special precautions other than general laboratory precautions are required.

Susceptibility

Very limited data are available. The results of the in vitro susceptibility studies done so far showed that amorolfine, bifonazole, itraconazole, and terbinafine MICs varied considerably among isolates of Malassezia furfur. The MICs obtained for other less commonly encountered species were also variable [1047, 1615, 1767, 1887]. In another comparative study, ketoconazole appeared to be more active than econazole and miconazole against Malassezia isolates. Of note, Malassezia furfur was the least susceptible Malassezia species to ketoconazole, econazole, miconazole, and tea tree oil [977].

For MICs of various antifungal drugs for Malassezia, see our susceptibility database.

Oral ketoconazole or itraconazole are commonly used for treatment of pityriasis versicolor [2199]. Antifungal therapy and removal of the catheter are the guidelines for treatment of catheter-related infections. Amphotericin B therapy may be used in these patients with catheter infections [2050].

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Malassezia furfur
Malassezia furfur Yeast in skin
Malassezia furfur
Malassezia furfur Cluster of yeast cells
Malassezia pachydermatis
Malassezia pachydermatis Yeast cells



References

55. Aly, R., and T. Berger. 1996. Common superficial fungal infections in patients with AIDS. Clin Infect Dis. 22 Suppl 2:S128-32.

129. Arnow, P. M., and R. Kushner. 1991. Malassezia furfur catheter infection cured with antibiotic lock therapy. Am J Med. 90:128-30.

146. Azimi, P. H., K. Levernier, L. M. Lefrak, A. M. Petru, T. Barrett, H. Schenck, A. S. Sandhu, G. Duritz, and M. Valesco. 1988. Malassezia furfur: a cause of occlusion of percutaneous central venous catheters in infants in the intensive care nursery. Pediatric Infectious Disease Journal. 7:100-103.

176. Barber, G. R., A. E. Brown, T. E. Kiehn, F. F. Edwards, and D. Armstrong. 1993. Catheter-related Malassezia furfur fungemia in immunocompromised patients. Am. J. Med. 95:365-370.

240. Bhattacharyya, T., M. Edward, C. Cordery, and M. D. Richardson. 1998. Colonization of living skin equivalents by Malassezia furfur. Med Mycol. 36:15-19.

276. Boekhout, T., M. Kamp, and E. Gueho. 1998. Molecular typing of Malassezia species with PFGE and RAPD. Med Mycol. 36:365-372.

298. Botterel, F., N. Curvale, F. Foulet, J. L. Poirot, and S. Bretagne. 2000. Frequency of intravascular catheter colonization by Malassezia sp in adult patients. J Mycologie Medicale. 10:203-206.

417. Chang, N. J., H. L. MIller, N. Watkins, M. J. Arduino, D. A. Ashford, G. Midgley, S. M. Aguero, R. Pinto-Powell, C. F. von Reyn, W. Edwards, M. M. McNeil, and W. R. Jarvis. 1998. An epidemic of Malassezia pachydermatis in an intensive care nursery associated with colonization of health care workers' pet dogs. N. Engl. J. Med. 338:706-711.

481. Crespo, M. J., M. L. Abarca, and F. J. Cabanes. 2000. Atypical lipid-dependent Malassezia species isolated from dogs with otitis externa. J Clin Microbiol. 38:2383-2385.

510. Dankner, W. M., S. A. Spector, J. Fierer, and C. E. Davis. 1987. Malassezia fungemia in neonates and adults: Complication of hyperalimentation. Rev. Infect. Dis. 9:743-753.

531. de Hoog, G. S., J. Guarro, J. Gene, and M. J. Figueras. 2000. Atlas of Clinical Fungi, 2nd ed, vol. 1. Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands.

755. Francis, P., and T. J. Walsh. 1992. Approaches to management of fungal infections in cancer patients. Oncology. 6:133-44.

790. Gagneur, A., J. Sizun, E. Vernotte, L. de Parscau, D. Quinio, A. M. Le Flohic, and R. Baron. 2001. Low rate of Candida parapsilosis-related colonization and infection in hospitalized preterm infants: a one-year prospective study. J Hosp Infect. 48:193-197.

908. Groll, A. H., and T. J. Walsh. 2001. Uncommon opportunistic fungi: new nosocomial threats. Clin Microbiol Infect. 7:8-24.

924. Gueho, E., T. Boekhout, H. R. Ashbee, J. Guillot, A. Van Belkum, and J. Faergemann. 1998. The role of Malassezia species in the ecology of human skin and as pathogens. Med Mycol. 36:220-229.

947. Gupta, A. K., Y. Kohl, J. Faergemann, and R. C. Summerbells. 2001. Epidemiology of Malassezia yeasts associated with pityriasis versicolor in Ontario, Canada. Med Mycol. 39:199-206.

948. Gupta, A. K., Y. Kohli, and R. C. Summerbell. 2000. Molecular differentiation of seven Malassezia species. J Clin Microbiol. 38:1869-1875.

977. Hammer, K. A., C. F. Carson, and T. V. Riley. 2000. In vitro activities of ketoconazole, econazole, miconazole, and Melaleuca alternifolia (Tea tree) oil against Malassezia species. Antimicrob. Agents Chemother. 44:467-469.

1019. Helm, K. F., and D. P. Lookingbill. 1993. Pityrosporum follucilitis folliculitis and severe pruritus in two patients with Hodgkin's disease. Arch Derm. 129:380-381.

1047. Hiratani, T., Y. Asagi, A. Matsusaka, K. Uchida, and H. Yamaguchi. 1991. In vitro antifungal activity of amorolfine, a new morpholine antimycotic agent. Jpn J Antibiot. 44:993-1006.

1216. Klotz, S. A. 1989. Malassezia furfur. Infect. Dis. Clin. North. Am. 3:53-64.

1251. Krcmery, V., I. Krupova, and D. W. Denning. 1999. Invasive yeast infections other than Candida spp. in acute leukaemia. J Hosp Infect. 41:181-194.

1294. Larocco, M., A. Dorenbaum, A. Robinson, and L. K. Pickering. 1988. Recovery of Malassezia pachydermatis from eight infants in a neonatal intensive care nursery: clinical and laboratory features. Pediatric Infectious Disease Journal. 7:398-401.

1295. Larone, D. H. 1995. Medically Important Fungi - A Guide to Identification, 3rd ed. ASM Press, Washington, D.C.

1361. Loeffler, J., H. Hebart, S. Magga, D. Schmidt, L. Klingspor, J. Tollemar, U. Schumacher, and H. Einsele. 2000. Identification of rare Candida species and other yeasts by polymerase chain reaction and slot blot hybridization. Diagn Microbiol Infect Dis. 38:207-212.

1364. Lopes, J. O., S. H. Alves, J. P. Benevenga, and C. S. Encarnacao. 1994. Nodular infection of the hair caused by Malassezia furfur. Mycopathologia. 125:149-152.

1464. Masure, O., C. Leostic, M. L. Abalain, C. Chastel, I. Yakoub-Agha, C. Berthou, and J. Briere. 1991. Malassezia furfur septicaemia in a child with leukaemia. J. Infect. 23:335-336.

1533. Mickelsen, P. A., M. C. Viano-Paulson, D. A. Stevens, and P. S. Diaz. 1988. Clinical and microbiological features of infection with Malassezia pachydermatis in high-risk infants. J. Infect. Dis. 157:1163-1168.

1582. Morrison, V. A., and D. J. Weisdorf. 2000. The spectrum of Malassezia infections in the bone marrow transplant population. Bone Marrow Transplant. 26:645-648.

1603. Myers, J. W., R. J. Smith, G. Youngbert, C. Gutierrez, and S. L. Berk. 1992. Fungemia due to Malassezia furfur in patients without the usual risk factors. Clin. Infect. Dis. 14:620-621.

1615. Nakamura, Y., R. Kano, T. Murai, S. Watanabe, and A. Hasegawa. 2000. Susceptibility testing of Malassezia species using the urea broth microdilution method. Antimicrob. Agents Chemother. 44:2185-2186.

1684. Okuda, C., M. Ito, W. Naka, T. Nishikawa, H. Tanuma, H. Kume, M. Hotchi, and G. Midgley. 1998. Pityriasis versicolor with a unique clinical appearance. Med Mycol. 36:331-334.

1767. Petranyi, G., J. G. Meingassner, and H. Mieth. 1987. Antifungal activity of the allylamine derivative terbinafine in vitro. Antimicrob. Agents Chemother. 31:1365-1368.

1859. Raabe, P., P. Mayser, and R. Weiss. 1998. Demonstration of Malassezia furfur and M-sympodialis together with M-pachydermatis in veterinary specimens. Mycoses. 41:493-500.

1874. Rapelanoro, R., P. Mortureux, B. Couprie, J. Maleville, and A. Taieb. 1996. Neonatal Malassezia furfur pustulosis. Arch Derm. 132:190-193.

1887. Regli, P., and H. Ferrari. 1989. In vitro action spectrum of a new antifungal agent derived from morpholine: amorolfin. Pathol Biol (Paris).

2050. Schleman, K. A., G. Tullis, and R. Blum. 2000. Intracardiac mass complicating Malassezia furfur fungemia. Chest. 118:1828-1829.

2077. Senczek, D., U. Siesenop, and K. H. Bohm. 1999. Characterization of Malassezia species by means of phenotypic characteristics and detection of electrophoretic karyotypes by pulsed-field gel electrophoresis (PFGE). Mycoses. 42:409-414.

2199. Sunenshine, P. J., R. A. Schwartz, and C. K. Janniger. 1998. Tinea versicolor. Int. J. Dermatol. 37:648-55.

2202. Sutton, D. A., A. W. Fothergill, and M. G. Rinaldi (ed.). 1998. Guide to Clinically Significant Fungi, 1st ed. Williams & Wilkins, Baltimore.

2250. Toth, J., M. Bausz, and L. Imre. 1996. Unilateral Malassezia furfur blepharitis after perforating keratoplasty. Br J Ophthalmol. 80:488.

2395. Weiss, R., P. Raabe, and P. Mayser. 2000. Genus Malassezia: Taxonomic classification and clinical significance in animals and man. Mycoses. 43:69-72.



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