La pitiriasis versicolor y las levaduras del género Malassezia

pH-Dependent Expression, Stability, and Activity of Malassezia restricta MrLip5 Lipase

Background

The lipophilic yeasts Malassezia spp. are normally resident on the surface of the human body, and often associated with various skin diseases. Of the 18 known Malassezia spp., Malassezia restricta is the most predominantly identified Malassezia sp. found on the human skin. Malassezia possesses a large number of genes encoding lipases to degrade human sebum triglycerides into fatty acids, which are required not only for their growth, but also trigger skin diseases. Previously, we have shown that MrLIP5 (MRET_0930), one of the 12 lipase genes in the genome of M. restricta, and is the most frequently expressed lipase gene in the scalp of patients with dandruff.

Objective

In this study, we aimed to analyze the activity, stability, and expression of MrLip5, with particular focus on pH.

Methods

We heterologously expressed MrLip5 in Escherichia coli, and purified and analyzed its activity and expression under different pH conditions.

Results

We found that MrLip5 was most active and stable and highly expressed under alkaline conditions, which is similar to that of the diseased skin surface.

Conclusion

Our results suggest that the activity and expression of MrLip5 are pH-dependent, and that this lipase may play an essential role at the M. restricta-host interface during disease progression.

Tinea versicolor of the neck as side effect of topical steroids for alopecia areata

Background: Treatment of alopecia areata (AA) involves use of high potency topical corticosteroids under occlusion that, even very effective, can lead to several adverse effects. Objective: We report 10 cases of patients with AA that, after using high potency topical corticosteroids, have developed tinea versicolor of the neck area. Methods: Ten patients with AA, aged 18-38 years, were prescribed with clobetasone propionate 0.05% cream under occlusion every other day but, after 3-4 months of treatment, they returned to our facility complaining the appearance of multiple white or red-brown round or oval macules in the neck area. Results: Diagnosis of pityriasis versicolor was confirmed by direct microscopy examination of skin scrapings in 10% potassion hydroxide (KOH) solution. All patients received systemic antifungal therapy associated with the daily use of ketoconazole shampoo. Conclusion: Tinea versicolor of the neck should be included among a rare but possible side effect of prolonged application of high potency topical steroids on the scalp. These cases reinforce the importance of careful dermatologic examination and recommend preventive measures in patients with alopecia areata that are using these drugs.

Epidemiological Characterization of Skin Fungal Infections Between the Years 2006 and 2010 in Korea

OBJECTIVES

The purpose of this study was to build and provide a basic database of skin fungal infections for the effective management of skin fungal infections in the future.

METHODS

We collected health insurance data between the years 2006 and 2010 from the Health Insurance Corporation (Seoul, Korea) and analyzed the data to determine the prevalence and treatment management of skin fungal infections.

RESULTS

Skin fungal infections were divided into two groups: namely dermatophytosis and other superficial mycoses. Dermatophytosis showed a higher prevalence (16,035,399 cases) than the other superficial mycoses (794,847 cases) within the study period. The prevalence rate decreased consecutively by 0.01% to 0.19% every year. The prevalence according to region showed that Jeolla-do had a high prevalence distribution. The prevalences in men and women were similar (7.01% vs. 6.26%). It is interesting to note that adults from the 50-79-year age group showed a higher prevalence than children and young adults. The average convalescence time (days) of dermatophytosis was longer than that of other superficial mycoses. The total medical expenses were also much higher in dermatophytosis than in the other superficial mycoses.

CONCLUSION

This study provides useful data for study trends of skin fungal infections.

The spectrum of Malassezia species isolated from students with pityriasis vesicolor in Nigeria

Pityriasis versicolor (PV) is a common superficial fungal infection of the skin caused by Malassezia. Initially M. furfur was suggested as its main aetiological agent; however, more recent studies suggest M. globosa as the dominant species. The possibility of a variance in predominant species based on geographical basis has not been fully evaluated. The objective of this study was to identify the Malassezia species on affected and non-affected skin of students with PV who reside in a tropical environment (Abuja, Nigeria) and correlate them to clinical characteristics. In this study, the literature on prevalence of Malassezia genus in PV was also reviewed. Samples were taken from 304 PV lesions and 110 normal appearing skin. Microscopy, culture and identification of Malassezia species utilising polymerase chain reaction-restriction fragment length polymorphism analysis were performed. Three Malassezia species were detected in PV with the major species being M. furfur. On normal appearing skin, M. furfur (77.6%) and M. restricta (10.4%) were both detected. No case of M. globosa was identified in this study. There was no significant difference between species identified and clinical features of PV. M. furfur is probably still the most predominant species causing PV in the tropical environment.

Molecular identification and prevalence of malassezia species in pityriasis versicolor patients from kashan, iran

Background:

Malassezia species are lipophilic yeasts found on the skin surface of humans and other warm-blooded vertebrates. It is associated with various human diseases, especially pityriasis versicolor, which is a chronic superficial skin disorder.

Objectives:

The aim of the present study was to identify Malassezia species isolated from patients’ samples affected by pityriasis versicolor, using molecular methods in Kashan, Iran.

Patients and Methods:

A total of 140 subjects, suspected of having pityriasis versicolor from Kashan, were clinically diagnosed and then confirmed by direct microscopic examination. The scraped skin specimens were inoculated in modified Dixon’s medium. DNA was extracted from the colonies and PCR amplification was carried out for the 26s rDNA region. PCR products were used to further restriction fragment length polymorphism by CfoI enzyme.

Results:

Direct examination was positive in 93.3% of suspected pityriasis versicolor lesions. No statistically significant difference was observed in the frequency of Malassezia species between women and men. The highest prevalence of tinea versicolor was seen in patients 21–30 years-of-age. No difference could be seen in the frequency of Malassezia species depending on the age of the patients. In total, 65% of patients with pityriasis versicolor had hyperhidrosis. The most commonly isolated Malassezia species in the pityriasis versicolor lesions were; Malassezia globosa (66%), M. furfur (26%), M. restricta (3%), M. sympodialis (3%), and M. slooffiae (2%). Malassezia species were mainly isolated from the neck and chest.

Conclusions:

This study showed M. globosa to be the most common Malassezia species isolated from Malassezia skin disorders in Kashan, Iran. The PCR-RFLP method was useful in the rapid identification of the Malassezia species. By using these methods, the detection and identification of individual Malassezia species from clinical samples was substantially easier.

Influence of systemic corticotherapy on the triggering of pityriasis versicolor

Pityriasis versicolor is a frequent mycosis and the use of systemic corticotherapy is one of its predisposing factors. This is an observational, cross-sectional, analytical and comparative study, conducted from January 2012 to January 2013 in the following outpatient clinics: Dermatology Service, Cassiano Antonio Moraes Hospital (HUCAM), Vitória, ES, Brazil; Nephrology Service, HUCAM; and Leprosy Department, Maruípe Health Unit, Vitória, ES, Brazil. Patients, undergoing long-term systemic corticotherapy (or not), were assessed with respect to the presence of pityriasis versicolor. If there was mycosis, a direct mycological examination would be carried out. The spss 17.0 software was used for the statistical analysis. From the total of 100 patients, nine had pityriasis versicolor, being eight from the corticotherapy group and one from the group with no use of corticosteroids. Regarding the patients with mycosis, the prevalent age ranged from 20 to 39 years, with six patients; six were women; seven mixed race; eight were undergoing long-term systemic corticotherapy; seven were taking low-dose systemic corticosteroids; four had leucocytosis; five had normal total cholesterol and triglycerides; and four had normal glycaemia. There was increased frequency of pityriasis versicolor in the group undergoing systemic corticotherapy with statistical significance, corroborating the only study on the topic (1962).

Human external ear canal as the specific reservoir of Malassezia slooffiae

The incidence of Malassezia species recovered from the external ear canal was characterized using culture medium optimized for Malassezia spp., CHROMagar Malassezia. The results of this study indicated that in healthy individuals M. slooffiae was the dominant Malassezia species followed by M. restricta.

Pathogenesis of dermatophytosis and tinea versicolor

Dermatophytoses are infections caused by keratinophilic fungi known as dermatophytes. Several steps are required for infection to take place: contact, adherence, and invasion of keratin layers. The severity of the infection depends on the type of agent, environmental factors, and the host immunologic status. Tinea versicolor is caused by the Malassezia spp yeasts, which are microorganisms that belong to normal biota in seborrheic areas, but some contributing factors, such as the application of oily preparations, creams, an increase in ambient humidity, corticosteroid abuse, or genetic predisposition can induce its overgrowth in both filamentous and yeast structures. Exposure to sunlight stimulates the production of azelaic acid, which causes the appearance of hypopigmented spots. Currently, there is no scientific explanation for hyperpigmented lesions.