Distribution of Malassezia species in patients with psoriasis and healthy individuals in Tehran, Iran.

BACKGROUND

Psoriasis is a non-contagious disorder that affects the skin as red scaly patches. Although the role of Malassezia species in the pathogenesis of psoriasis is still not fully understood, it is thought that these lipophilic yeasts might be a trigger factor in the exacerbation of psoriatic lesions.

METHODS

Using culture in a specific medium followed by the polymerase chain reaction-restriction fragment length polymorphism method, the presence of Malassezia species in the skin of 110 patients with psoriasis was compared with that in a control group of 123 healthy patients.

RESULTS

The recovery rate of Malassezia species from the skin of patients with psoriasis was significantly lower than that in the controls. In both psoriatic and healthy skin, Malassezia globosa was isolated as the predominant species. In psoriatic patients, the rate of colonization of Malassezia furfur and Malassezia restricta was almost twice that in the controls, whereas M. globosa was isolated more frequently from healthy individuals than from patients.

CONCLUSIONS

Considering the higher lipase activity secretion by M. furfur in comparison with other Malassezia species, the enzymatic release of arachidonic acid and its metabolites by M. furfur may exacerbate the inflammatory and hyperproliferative changes observed in psoriasis.