Microbiology and Physiology
All types of Malassezia with the exception of M. pachydermatis, a zoophilic species, oblige skin lipids for development, in light of the fact that they don’t incorporate long-chain soaked unsaturated fats. Because of this lipid prerequisite, Malassezia don’t develop on a standard contagious society medium, a paramount reality to think about in diagnosing infections brought on by these yeasts. Malassezia may be developed on Leeming and Notman agar or Dixon agar, which both hold unsaturated fats, or Littman agar supplemented with olive oil.
Malassezia yeasts prepare various synthetic aggravates that may assume a part in pathogenesis of Malassezia-related skin illnesses. Azaleic corrosive is a dicarboxylic corrosive that restrains tyrosinase, a key chemical in melanin blend, bringing about less melanin processing. Clinically, this may be evident as hypopigmentation in skin influenced by tinea versicolor. Pityriacitrin is a yellow intensify that may demonstration as a characteristic sunscreen, retaining ultraviolet light in skin influenced with tinea versicolor, additionally prompting relative hypopigmentation (Mayser, Schäfer, Krämer, Irlinger, & Steglich, 2002). Malassezin is an aryl hydrocarbon receptor agonist that incites apoptosis (cell passing) in melanocytes, likewise perhaps helping hypopigmentation in tinea versicolor (Krämer, Podobinska et al., 2005).
Pityrialactone is an indole alkaloid (tryptophan subordinate) that fluoresces under 366 nm ultraviolet light (Mayser et al., 2003). This compound may be answerable for the way that tinea versicolor is fluorescent under Wood’s light.
Not at all like most pathogenic microorganisms, which incite an inflammatory reaction in their host, Malassezia sneak by the radar of the invulnerable framework, having an immunosuppressive impact. Malassezia actuate keratinocytes and fringe blood mononuclear cells to down-control the star provocative cytokines interleukin-1, interleukin-6, and tumor corruption variable alpha in an interleukin-10 ward way. This adjustment of the resistant framework gives off an impression of being interceded by Malassezia’s lipid-rich capsular layer, as it doesn’t happen when the container is evacuated.
Likewise, Malassezia produce pityriarubins, red indole alkaloids that repress the neutrophil respiratory rush in vitro and additionally restrain 5-lipoxygenase, a compound included in processing of incendiary go betweens (Krämer, Kessler et al., 2005). Malassezia’s capacity to tweak the insusceptible framework may illustrate how it can develop so effectively on solid people as a piece of the typical skin verdure. It likewise illustrates the absence of skin irritation seen in tinea v