The Investigation on the Distribution ofMalasseziaYeasts on the Normal Korean Skin by 26S rDNA PCR-RFLP

Abstract

Background: Malassezia yeasts are normal flora of the skin that are discovered in 75∼98% of health subjects, but since its association with various skin disorders have been known, many studies have been conducted in the distribution of the yeasts. Objective: To isolate, identify, and classify Malassezia yeasts from the normal human skin of Koreans by using the rapid and accurate molecular biology method (26S rDNA PCR-RFLP) which overcome the limits of morphological and biochemical methods, and to gather a basic database that will show its relation to various skin diseases. Methods: Malassezia yeasts were cultured from clinically healthy human skin using scrub-wash technique at five sites (forehead, cheek, chest, upper arm, and thigh) and swabbing technique at scalp in 160 participants comprised of 80 males and 80 females aged from 0 to 80. Identification of obtained strains were placed into the one of the 11 species by 26S rDNA PCR-RFLP. Results: An overall positive culture rate was 62.4% (599/960). As shown in the experiment groups by their age, the positive culture rate was the highest (74.2%) in the age 21∼30 and 31∼40 (89/120). In the experiment groups by different body areas, the scalp showed the highest positive culture rate of 90% (144/160). On analysis of 26S rDNA PCR-RFLP, M. globosa was the most predominant species in the age 0∼10 (32.8%), 11∼20 (28.9%), 21∼30 (32.3%). M. restricta was identified as predominant species in the age 41∼50 (27.9%), 61∼70 (31.5%) and 71∼80 (24.0%). In the age 31∼40 years, M. sympodialis was found to be the most common species (24.6%). According to body site, M. restricta was more frequently recovered in the scalp (56.8%), forehead (39.8%) and cheek (24.0%) and while M. globosa was more frequently recovered in the chest (36.8%). Higher positive culture rates of Malassezia yeasts were shown in male subjects than female counterparts in all body areas except scalp (p＜0.05). Especially in this study, M. dermatis, newly isolated Malassezia species from atopic dermatitis patient in Japan, was isolated and identified in 19 cases (1.9%) in healthy subjects. Conclusion: The key is to recognize the existence of a difference in the type of Malassezia species in different ages as well as body areas, which reflects differing skin lipid levels in various ages and different body areas. Moreover, 26S rDNA PCR-RFLP analysis which was opted in this study could provide a sensitive and rapid identification system for Malassezia species, which may be applied to epidemiological surveys and clinical practice.

Molecular Analysis of Malassezia Microflora on the Skin of the Patients with Atopic Dermatitis

“…However, there were differences with a respect to the commonly isolated species, not only between normal healthy individuals and the patients with various skin diseases, but also between different countries. For the healthy subjects from a previous study, the dominant species was M. globosa 18 , while M. sympodialis was the dominant species in a study from Canada 12 . For the patients with AD in this study, the dominant species was M. sympodialis, while M. furfur 15 or M. globosa and M. restricta 16 were the dominant species in Japan and M.…”

A study on malassezia micro flora in the skin of healthy individuals in North Kerala, India

“…This is in agreement with the studies done in normal healthy Korean subjects at 62.4% and 63.6%. 13,14 An Iranian study showed similar rates at 62%. 15 Higher rate of Malassezia colonization compared with the present study was also noticed in studies done on healthy human skin in Bosnia and Herzegovina (65%) and Sweden (84%).…”

“…20 Mixed cultures were also observed in a couple of studies from normal healthy Korean subjects based on molecular based studies. 14,13 However, diverse sites yielded different species.…”

“…16,23 This is in contrast with a study on healthy Korean subjects. 13 Being lipid dependent, they are commonly found to be distributed in areas rich in sebaceous glands, such as the chest, back, neck and shoulders. They reside in the stratum corneum and hair infundibulum, where they utilize sebum for their growth and maintenance.…”

“…A total of 120 apparently healthy men and 120 women without any skin diseases or who were not treated for Malassezia associated skin diseases were selected for the study. They were grouped according to their age as (0-10), (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), (21)(22)(23)(24)(25)(26)(27)(28)(29)(30), (31-40), (41-50), (> 51) where each group consisted of 40 subjects (20 men and 20 women). The specimens consisted of scrapings collected from chest, back and neck from each subject totaling 720 sites.…”