Malassezia is a component of normal cutaneous resident microbiota. The aim of this study was to quantitatively clarify the differences in cutaneous Malassezia microbiota in healthy subjects by sex, body part and season. Samples were collected from the forehead, cheek, upper chest and upper back of 20 healthy men and 20 healthy women (average age 32 years) in summer and winter by the swab method. Malassezia DNA was analyzed using a real-time PCR system. As a result, in sex, body parts and season, men, the upper trunk and summer showed the highest total numbers of cutaneous Malassezia species on average. There were also differences depending on the analytical method. The predominant species were M. restricta on the face of men, M. globosa and M. dermatis on the upper trunk of men, and M. globosa and M. sympodialis on the upper trunk of women. This study clarified that the cutaneous Malassezia microbiota of healthy subjects differed by sex, body part and season.

To clarify the relationship between major cutaneous microorganisms (Propionibacterium, Staphylococcus and Malassezia spp.) and acne vulgaris (acne), we examined the microbiota quantitatively in the follicular contents of inflammatory acne and on the facial skin of patients with acne. Fifteen Japanese untreated acne outpatients were studied. The follicular contents from inflammatory acne lesions of the face were collected using a comedo extractor. The skin surface samples were obtained by the swab method from 10 cm(2) of facial skin. The microbiota was analyzed using polymerase chain reaction. The microbiota in follicular contents was similar to that on the skin surface, namely, there were large populations of Propionibacterium spp., Staphylococcus spp. and Malassezia spp. Moreover, the number of Malassezia spp. on the skin surface was correlated with that of inflammatory acne and that in follicular contents. This study clarified that there are large populations of Propionibacterium spp., Staphylococcus spp. and Malassezia spp. in follicular contents. These results suggest the possibility that not only Propionibacterium acnes but also other cutaneous resident microorganisms are related to acne. Particularly, we considered that Malassezia spp. is closely related.

To clarify the influence of the fatty acid composition of sebum in acne vulgaris, we investigated the amounts and fatty acid compositions of triglycerides (TG) and free fatty acids (FFA), and the amounts of cutaneous superficial Propionibacterium acnes in acne patients and healthy subjects. The foreheads of 18 female patients, 10 male patients, 10 healthy females and 10 healthy males were studied in a Japanese population. There were significant differences in the amounts of sebum, TG and cutaneous superficial P. acnes, as well as the fatty acid compositions of TG and FFA between acne patients and healthy subjects in females. Their fatty acid compositions were correlated with the amount of TG with or without acne. It was clarified that the fatty acid compositions of TG and FFA depended on the amount of TG, and there were no differences in the fatty acid composition in the presence and absence of acne.

Malassezia folliculitis [MF] is caused by the invasion of hair follicles by large numbers of Malassezia cells, but it remains unclear which Malassezia species are involved in the disease. To clarify this situation, Malassezia species isolated from lesions of MF patients were analyzed by both culture and non-culture methods. In addition, Malassezia species recovered from the non-lesion areas of the skin of MF patients and skin samples of healthy subjects were included in this study. The test population consisted of 32 MF patients and 40 healthy individuals. The lesions were obtained using a comedone extractor, while swabs were employed to obtain skin samples from non-lesion areas of the patients and healthy subjects. Malassezia DNA was analyzed using a real-time PCR technique. The detection limit of the culture method was 5 CFU/cm(2) as opposes 50 cells/cm(2) with non-culture procedures. The predominant species recovered from MF lesions were M. globosa and M. sympodialis by culture method analysis, and M. restricta, M. globosa, and M. sympodialis with non-culture methods. These results were in agreement with those found with samples from non-lesion skin areas of MF patients and healthy subjects. This study clarified that MF is caused by Malassezia species that are part of the cutaneous microflora and not by exogenous species.

Objectives: We investigated the facial skin microbiota of Japanese acne patients. Methods: Skin swab samples were obtained from 100 acne patients and 28 healthy controls to evaluate Propionibacterium and Staphylococcus spp. using a culture method. Malassezia spp. were evaluated using a nonculture method. Antibiotic resistance of Propionibacterium spp. was also examined. Results: Acne patients and controls did not show significant differences in Propionibacterium and Staphylococcus spp. populations. However, the number of Malassezia globosa from patients was greater than that from controls. Moreover, the number of Propionibacterium spp. from patients carrying antibiotic-resistant strains was significantly greater than that from patients not carrying them. Conclusions: The present study characterized the facial skin microbiota of Japanese acne patients, suggesting a correlation between acne and quantitative differences in Malassezia microbiota. It was also found that the antibiotic resistance of Propionibacterium spp. may affect its abundance in the skin.