Identification of the predominant species of Malassezia sp in samples from patients with pityriasis versicolor, folliculitis and seborrheic dermatitis

Abstract

Malassezia sp. It is a dimonic fungus, which can be isolated from human skin because it is a normal microbiota of the skin.
It is recognized as the causal agent of three superficial mycoses: pityriasis versicolor, seborrheic dermatitis and
folliculitis. The development of these pathologies is influenced by factors such as hot weather and prolonged exposure to the sun. In the present study, sampling was carried out in three military bases in the Pacific with a total population of 1,261 patients. A total of 95 samples from patients who presented lesions suggestive of pityriasis versicolor, seborrheic dermatitis or folliculitis were evaluated. Direct examination with KOH and Parker ink revealed the presence of mycelium and/or yeasts in 62% of the samples. Sabouraud was initially cultured with antibiotics and Sabouraqd agar with antibiotics and olive oil. From these cultures, a yeast-like growth was obtained in 31 samples (33%). For subsequent identification, modified Dixon's differential agar was used, obtaining 90% growth (28 samples). These samples were reseeded on simple Sabouraud agar, obtaining growth in only 8 of them (29%). those that were eliminated from the study because they were identified as non-lipophilic yeasts. The remaining 20 samples, corresponding to 71%. they were submitted to biochemical tests of catalase and urease: and microscopic evaluation with lactophenol blue. obtaining results corresponding to Malassezia furfur, which allows affirming that this species is the causal agent of pityriasis versicolor lesions in Guatemala.