Malassezia: a fungus among us

Hypopigmentation caused by Malassezia (Photo: astrium.com)

A group of clinical researchers from the School of Biochemistry and Pharmacy at the National University of Rosario received the Best Scientific Work Award for their work in the assessment of culture media for studies on Malassezia growth and drug sensitivity. The ceremony took place during the Argentine Meeting on Micology in Posadas, Misiones.

According to Silvana Ramadán, the researcher who presented the work, “I believe that more than the methodology applied, our dedication, the bench work and our efforts to obtain the yeast isolates were considered”.

Along with Silvana Ramadán, authors  Maximiliano Sortino , Lucía Bulacio, Clara López  and Laura Ramos were interested in a kind of yeast that produces human mycoses, known as Malassezia. Formerly known as Pitirosporum, name we have heard in many commercial ads refering to anti dandruff shampoos against Pitirosporum ovale, this fungus is currently considered to be the same as Malazzesia. This yeast species is very difficult to propagate since its nutritional requirements are very specific and heavily-dependent on lipids. At the same time, the development of appropriate culture media is absolutely neccesary if we are to determine this fungus sensitivity to different antifungal drugs used in the treatment of patients.

Malassezia is usually present on normal human skin (and in dogs) but under some conditions may overgrow leading to skin manifestations and folliculitis. In hospitalized patients, Malassezia may display a more agressive behaviour leading to catheter-associated sepsis, especially in those cases where patients receive lipid-based parenteral nutrition.

“When I was a student, Malassezia furfur was the only species we had knowledge of. Now, we know that there are more than 15 species and it is hard to distinguish between them, especially because they are hard to grow in regular culture media and also very difficult to maintain in the lab since they require lipid-rich media. That is the reason why these yeasts are found in patients with sebhorreic skin and in body areas such as chest and face”, added Ramadán.

Antifungal sensitivity tests are neccesary to determine drugs and concentrations required to treat patients. This becomes a problem when no standard methods are available to grow Malassezia in optimal conditions. The two methods employed by the researchers yielded results comparable to previously published data. The next steps include the standardization of the different variables as well as correlation studies between both techniques. The aim is to provide new approaches to determine antifungal resistance for Malassezia at the hospital and community levels.

Source:
http://www.unr.edu.ar/noticia/3738/premio-al-mejor-trabajo-cientifico-sobre-micologia-clinica/