The Distibution of Malassezia Yeasts on Normal Human Skin by Culture study Using the Swabbing Technique

Kwon, Hyuk Cheol; Kang, Sung Ho; Kim, Han Uk

Abstract

BACKGROUND: The distribution of Malassezia yeasts on normal human skin was varied according to the age and race of the volunteers and the methodologies used. In Korea, most reports of Malassezia yeast distribution have relied on direct skin smears rather than culture methods.
OBJECTIVE
The aim of this work was to perform a comprehensive survey of the distribution of Malassezia yeasts on normal human skin to provide a base line for a companion study of Malassezia yeasts in patients with various dermatoses.
METHODS
Malassezia yeasts were cultured using the swabbing technique from the scalp, forehead, chest, upper back, upper arm and upper thigh in 137 subjects, infancy to 80 years of age.
RESULTS
Malassezia yeasts were present in the lowest incidence(0-30%) on six sites of infants and present in 60.0-66.7% on the sebum-rich sites (scalp, forehead, chest, upper back) of children aged 1-9. Malassezia yeasts were present in 80.0-86.7% on the sebum-rich sites of the elderly group(over 60 years of age), about the same frequency as in the middle-aged groups. The population density of these organisms was significantly higher on the upper back than on the forehead, chest, upper arm and upper thigh in all age groups except the infant group and the group aged 1 to 9 (p<0.05). There were no regular quantitative variations in the distribution of Malassezia yeasts on a given site between age groups. On Leeming and Notman media, besides three morphotypes of Malassezia yeasts reported by Cunningham et al(1990), one additional type was identified.
CONCLUSION
The results showed regional variations in the distribution of Malassezia yeasts in all ages except infancy and no regular age variations on a given site. Additionally, four colony types of Malassezia yeasts were found. The findings of our study coold help to investigate the role of Malassezia yeasts in related disorders.