[Malassezia spp.: interactions with topically applied lipids-a review : Malassezia and topically applied lipids]

Lipophilic Malassezia yeasts are an important part of the human resident skin flora, especially in seborrheic areas. Besides mutualistic interactions with the host they are also linked to diseases although the specific causes are not yet comprehensively understood. The amount of available lipids on the skin correlates with the Malassezia density and also with the occurrence of certain diseases like tinea versicolor. Here, the naturally produced lipids of the sebaceous glands play a role. Hardly studied thus far is the impact of topically applied lipids. Here, growth promotion as well as inhibition of Malassezia cells as well as the production of new metabolites through ester cleavage are possible. One example is the release of antimicrobial fatty acids from hydroxypropyl caprylate through the action of Malassezia lipases. This "self-kill" principle results in the reduction of the amount of Malassezia cells and can be applied as new therapy option for dandruff treatment. A better understanding of the interaction between topica and Malassezia would increase their skin tolerance and open new therapy options.

Detection and identification of Malassezia species in domestic animals and aquatic birds by PCR-RFLP

The present study aimed at detection and species-level identification of the Malassezia yeasts in domestic animals and aquatic birds by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Samples were collected using tape strips and swabs from 471 animals including 97 horses, 102 cattle, 105 sheep, 20 camels, 60 dogs, 30 cats, 1 hamster, 1 squirrel, 50 aquatic birds and 5 turkeys. Tape-strip samples were examined by direct microscopy. All samples were inoculated on modified Leeming and Notman agar medium. DNA extracted from the yeast colonies was amplified by PCR using primers specific for 26S rDNA. RFLP of the PCR products was performed using Hin6I enzyme, and PCR and RFLP products were visualized by agarose gel electrophoresis. Malassezia yeasts were detected at the following frequencies: 15.46% in horses, 12.74% in cattle, 12.38% in sheep, 28.33% in dogs, 26.66% in cats and 26% in aquatic birds. Eighty colonies of 6 species were isolated: Malassezia globosa 41.25%, Malassezia furfur 22.5%, Malassezia restricta 15%, Malassezia sympodialis 15%, Malassezia pachydermatis 5% and Malassezia slooffiae 1.25%. Therefore different lipophilic Malassezia species are found in a wide diversity of animals and aquatic birds. PCR-RFLP is a suitable technique for identification of different Malassezia species.

Molecular biological identification of malassezia yeasts using pyrosequencing

Background

A Pyrosequencing assay has been used in identification of fungal species such as Candida or Aspergillus and diagnosis of pathogenic bacteria such as Helicobacter pylori but there has been no report on successful isolation and identification of Malassezia yeasts using the pyrosequencing method.

Objective

Examine the applicability and plausibility of the pyrosequencing method in identification of the Malassezia species.

Methods

At internal transcribed spacer (ITS) sites 1 and 2, three primers were developed using Pyrosequencing Assay Design Software (Biotage AB). Pyrosequencing was performed on 11 standard strains and 83 genomic DNA samples obtained from 66 healthy controls aged from 1 to 80.

Results

The eleven Malassezia standard species and 83 genomic DNA samples were successfully identified using the pyrosequencing assay.

Conclusion

The pyrosequencing method is a new tool for analysis of Malassezia yeasts, and its precision and rapidity suggests its clinical applicability.

Generalized dermatitis associated with Malassezia overgrowth in cats: A report of six cases in France

We recently observed six cases of generalized dermatitis associated with Malassezia overgrowth in cats presented to the Veterinary College of Alfort, France. Elevated numbers of yeasts were observed in lesional skin by cytology and culture. Skin lesions occurred on the face, ventral neck, abdomen and ear canals and were characterized by some degree of alopecia, erythema and crusting. In most cases, pruritus was intense. The species M. pachydermatis was systematically isolated.

Skin Characteristics in Patients with Pityriasis Versicolor Using Non-Invasive Method, MPA5

Background

Skin pigmentary changes of pityriasis versicolor may occur as either hyperpigmented or hypopigmented lesions, depending on the outcome of interactions between Malassezia yeasts and the skin, such as lipoperoxidation process, stimulus of inflammatory cell to melanocytes, and increased thickness of keratin layer.

Objective

To investigate skin characteristic factors that enhance the susceptibility to Malassezia yeasts and provoke different color changes of pityriasis versicolor patients.

Methods

To clarify these factors, we investigated the skin characteristics of pityriasis versicolor patients, using a non-invasive method known as MPA 5® (Courage and Khazaka, Germany). A total of 90 normal healthy subjects and 30 pityriasis versicolor patients were included in this study.

Results

Both hyperpigmented and hypopigmented pityriasis versicolor skin lesions showed higher humidity, increased sebum excretion rate and increased transepidermal water loss (TEWL) values than normal healthy subjects. But no significant difference of specific Malassezia yeasts species between hyperpigmented and hypopigmented skin lesions was evident.

Conclusion

These results indicate that higher humidity and increased sebum level provide a better growing environment of Malassezia yeasts in the skin, leading to the assumption that interaction between Malassezia yeasts and skin barrier materials makes disruption of skin barrier causing increased TEWL.

Epidemiologic Study of Malassezia Yeasts in Patients with Malassezia Folliculitis by 26S rDNA PCR-RFLP Analysis

BACKGROUND

So far, studies on the inter-relationship between Malassezia and Malassezia folliculitis have been rather scarce.

OBJECTIVE

We sought to analyze the differences in body sites, gender and age groups, and to determine whether there is a relationship between certain types of Malassezia species and Malassezia folliculitis.

METHODS

Specimens were taken from the forehead, cheek and chest of 60 patients with Malassezia folliculitis and from the normal skin of 60 age- and gender-matched healthy controls by 26S rDNA PCR-RFLP.

RESULTS

M. restricta was dominant in the patients with Malassezia folliculitis (20.6%), while M. globosa was the most common species (26.7%) in the controls. The rate of identification was the highest in the teens for the patient group, whereas it was the highest in the thirties for the control group. M. globosa was the most predominant species on the chest with 13 cases (21.7%), and M. restricta was the most commonly identified species, with 17 (28.3%) and 12 (20%) cases on the forehead and cheek, respectively, for the patient group.

CONCLUSION

Statistically significant differences were observed between the patient and control groups for the people in their teens and twenties, and in terms of the body site, on the forehead only.

Epidemiologic Study of Malassezia Yeasts in Seborrheic Dermatitis Patients by the Analysis of 26S rDNA PCR-RFLP

BACKGROUND

This case-control study concerns a molecular biological method based on the data gathered from a group of Korean subjects to examine the distribution of Malassezia yeasts in seborrheic dermatitis (SD) patients. Cultures for Malassezia yeasts were taken from the foreheads, cheeks and chests of 60 patients with SD and in 60 healthy controls of equivalent age.

OBJECTIVE

The purpose of this study is to identify the relationship between certain species of Malassezia and SD. This was done by analyzing the differences in the distribution of Malassezia species in terms of age and body parts of the host with healthy controls.

METHODS

26S rDNA PCR-RFLP, a fast and accurate molecular biological method, was used to overcome the limits of morphological and biochemical methods.

RESULTS

The positive Malassezia culture rate was 51.7% in patients with SD, which was lower than that of healthy adults (63.9%). M. restricta was dominant in patients with SD (19.5%). Likewise, M. restricta was identified as a common species (20.5%) in healthy controls. In the ages 31~40, M. restricta was found to be the most common species (31.6%) among SD patients.

CONCLUSION

According to the results of the study, the most frequently isolated species was M. restricta (19.5%) in patients with SD. There was no statistically significant difference in the distribution of Malassezia species between the SD patients and healthy control groups.

Comparison of Nested PCR and RFLP for Identification and Classification of Malassezia Yeasts from Healthy Human Skin

BACKGROUND

Malassezia yeasts are normal flora of the skin found in 75~98% of healthy subjects. The accurate identification of the Malassezia species is important for determining the pathogenesis of the Malassezia yeasts with regard to various skin diseases such as Malassezia folliculitis, seborrheic dermatitis, and atopic dermatitis.

OBJECTIVE

This research was conducted to determine a more accurate and rapid molecular test for the identification and classification of Malassezia yeasts.

METHODS

We compared the accuracy and efficacy of restriction fragment length polymorphism (RFLP) and the nested polymerase chain reaction (PCR) for the identification of Malassezia yeasts.

RESULTS

Although both methods demonstrated rapid and reliable results with regard to identification, the nested PCR method was faster. However, 7 different Malassezia species (1.2%) were identified by the nested PCR compared to the RFLP method.

CONCLUSION

Our results show that RFLP method was relatively more accurate and reliable for the detection of various Malassezia species compared to the nested PCR. But, in the aspect of simplicity and time saving, the latter method has its own advantages. In addition, the 26S rDNA, which was targeted in this study, contains highly conserved base sequences and enough sequence variation for inter-species identification of Malassezia yeasts.